If you just got here … it’s almost time… and what is time anyway?
If you just got here … it’s almost time… and what is time anyway?
If the rock that hit the Earth 66 million years ago had been just a little later, or a little earlier, we might not be here talking about it.
“They illustrate what happened in the seconds and hours after the impact, revealing that had the huge asteroid struck the Earth a moment earlier, or later, the destruction might not have been total for the dinosaurs. And if they still roamed the world, we humans may never have come to rule the planet.” — BBC Two — The Day the Dinosaurs Died
I was once almost eaten by a shark in the warm waters off Chicxulub. It was 1972 and I was on holiday in Mexico. We were spending a week in the Yucatan. After leaving Merida our concierge, driver, cook, and friend took us to his mother-in-law’s summer home on the beaches of Chicxulub. My spanish is not good and I thought we had rented the little cabin/hut in the back of the beach front property. “No, no esa cosa pequeña … esa casa grande!”
It was awesome. The sand, the art, the cool tiles, the warm sea … and it seemed that we had it all to ourselves. After a few days of our fabulous holiday, my partner had to go into town about the car rental, but despite the warnings I’d heard about swimming with a partner, I couldn’t stay out of the ocean and I went into those waves anyways. I’m splashing around about 100 feet off shore when I noticed a small boy on the beach, jumping up and down, waving, and yelling at me … “hola!” “What’s that you’re saying?” I swam back to shore but he ran away, up the beach, toward the nearby small town of Chicxulub.
My partner and I regularly walked into Chicxulub in the evening, where we ate street food and soaked up the ambiance. That night, as we walked along the beach, we could see there was quite a happening on the town dock, boats and trucks, lots of people, lights and action. It wasn’t long before we were at the scene and had it figured out. They were hauling a huge dead shark onto the dock. This was no baby shark. It was gianormous. Indeed I’m convinced it was the inspiration for the movie “Jaws” which was released only a few years later. When people talked about the movie I thought, that was nothing! You should have seen the monster we saw in Chicxulub!
Anyways, we left the dock and walked the short distance to a large restaurant we had planned to eat at on our last day in the Yucatan. We enter, and who is the first person I see? The boy who was on the beach that morning! He seemed really happy to see me and soon his Dad was ushering us to a table where he handed us a couple of menus. And there, on the menu, was the word the boy had been yelling at me that afternoon. Hola! tiburón! tiburón! tiburón! “
Then, in 1980, the father-and-son team of scientists Luis and Walter Alvarez, suggested the hypothesis that the mass extinction of the dinosaurs was caused by the impact of a large asteroid hitting Earth. And last year, ECORD, the European Consortium for Ocean Research Drilling, launched an expedition to drill core from the crater peak of that event. Here is the web page.
Here is the flyer.
Earthshine Rocks in Space Earth Craters, North America
This is: North American Impact Craters
|RR||Haviland||Kansas, USA||N 37° 35'||W 99° 10'||<0.001||0.015||yes||yes||n/a|
|Barringer||Arizona, USA||N 35° 2'||W 111° 1'||0.049 ± 0.003||1.186||yes||yes||n/a|
|ZZ||Odessaa||Texas, USA||N 31° 45'||W 102° 29'||<0.05||0.168||yes||yes||n/a|
|G||New Quebec||Quebec, Canada||N 61° 17'||W 73° 40'||1.4 ± 0.1||3.44||yes||yes||n/a|
|B||Haughton||NWT, Canada||N 75° 22'||W 89° 41'||23 ± 1||24||yes||yes||NASA|
|Wanapitei||Ontario, Canada||N 46° 45'||W 80° 45'||37 ± 2||7.5||yes||yes||n/a|
|PP||Chesapeake Bay||Virginia, USA||N 37° 17'||W 76° 1'||35.5 ± 0.6||85||no||yes||USGS|
|I||Mistastin||Nfld/Lab, Canada||N 55° 53''||W 63° 18'||38 ±4||28||yes||yes||n/a|
|CC||Montagnais||Nova Scotia, Canada||N 42° 53'||W 64° 13'||50.5 ± 0.76||0.76||no||no||n/a|
|BBB||Marquez||Texas, USA||N 31° 17'||W 96° 18'||58 ± 2||13||no||no||n/a|
|O||Eagle Butte||Alta, Canada||N 49° 42'||W 110° 30'||<65||10||no||yes||n/a|
|CCC||Chicxulub||Yucatan, Mexico||N 21° 20'||W 89° 30'||64.98 ± 0.05||170||no||yes||wiki|
|II||Manson||Iowa, USA||N 42° 35'||W 94° 33'||73.8 ± 0.3||35||no||no||wiki|
|A||Avak||Alaska, USA||N 71° 15'||W 156° 38'||>95||12||no||no||n/a|
|C||Steen River||Alta, Canada||N 59° 30'||W 117° 38'||95 ± 7||25||no||no||n/a|
|L||Deep Bay||Sask, Canada||N 56° 24'||W 102° 59||100± 50||13||yes||yes||n/a|
|J||Carswel||Sask, Canada||N 58° 27'||W 109° 30'||115± 10||39||yes||yes||n/a|
|P||Maple Creek||Sask, Canada||N 49° 48'||W 109° 6'||;<75||6||no||no||n/a|
|U||West Hawk||Manitoba, Canada||N 49° 46'||W 95° 11'||100± 50||2.44||yes||yes||wiki|
|NN||Kentland||Indiana, USA||N 40° 45'||W 87° 24'||<97||13||yes||yes||n/a|
|AAA||Sierra Madera||Texas, USA||N 30° 36'||W 102° 55'||<100||13||yes||yes||n/a|
|HH||Upheaval Dome||Utah, USA||N 38° 26'||W 109° 54'||<170||10||yes||yes||n/a|
|R||Viewfield||Sask, Canada||N 49° 35'||W 103° 4'||190± 20||2.5||no||no||n/a|
|EE||Red Wing||N. Dakota, USA||N 47° 36'||W 103° 33'||200 ± 25||9||no||no||n/a|
|VV||Wells Creek||Tennessee, USA||N 36° 23'||W 87° 40'||200 ± 100||12||yes||yes||n/a|
|K||Gow||Sask, Canada||N 56° 27'||W 104° 29'||<250||5||yes||yes||n/a|
|T||St. Martin||Manitoba, Canada||N 51° 47'||W 98° 32'||220 ± 32||40||yes||yes||n/a|
|AA||Manicouagan||Quebec, Canada||N 51° 23'||W 68° 42'||214 ± 1||100||yes||yes||n/a|
|KK||Des Plaines||Illinois, USA||N 42° 3'||W 87° 52'||<280||8||no||no||n/a|
|M||Clearwater West||Quebec, Canada||N 56° 13'||W 74° 30'||290± 20||36||yes||yes||n/a|
|N||Clearwater East||Quebec, Canada||N 56° 5'||W 74° 7'||290± 20||26||yes||yes||n/a|
|OO||Serpent Mound||Ohio, USA||N 39° 2'||W 83° 24'||<320||8||yes||yes||n/a|
|TT||Decaturville||Missouri, USA||N 37° 54'||W 92° 43'||<300||6||yes||yes||n/a|
|UU||Crooked Creek||Missouri, USA||N 37° 50'||W 91° 23'||320 ± 80||7||yes||yes||n/a|
|XX||Flynn Creek||Tennessee, USA||N 36° 17'||W 85° 40'||360 ± 20||3.55||yes||yes||n/a|
|E||Nicholson||NWT, Canada||N 62° 40'||W 102° 41'||<400||12.5||yes||yes||n/a|
|BB||Charlevoix||Quebec, Canada||N 47° 32'||W 70° 18'||357 ± 15||54||yes||yes||n/a|
|H||La Moinerie||Quebec, Canada||N 57° 26'||W 66° 37'||400± 50||8||yes||yes||n/a|
|Q||Elbow||Sask, Canada||N 50° 59'||W 106° 43'||395 ± 25||8||no||no||n/a|
|YY||Middlesboro||Kentucky, USA||N 36° 37'||W 83° 44'||<300||6||yes||no||n/a|
|F||Couture||Quebec, Canada||N 60° 8'||W 75° 20'||430± 25||8||yes||yes||n/a|
|Glasford||Illinois, USA||N 40° 36'||W 89° 47'||<430||4||no||no||n/a|
|D||Pilot||NWT, Canada||N 60° 17'||W 111° 1'||445± 2||6||yes||yes||n/a|
|S||Newporte||N. Dakota, USA||N 48° 58'||W 101° 58'||<500||3.2||no||no||n/a|
|V||Slate Islands||Ontario, Canada||N 48° 40'||W 87° 0'||~450||30||yes||yes||odale|
|Z||Presqu'île||Quebec, Canada||N 49° 43'||W 74° 48'||<500||24||yes||yes||odale|
|FF||Brent||Ontario, Canada||N 46° 5'||W 78° 29'||450 ± 30||3.8||yes||yes||passc|
|JJ||Glover Buff||Wisconsin, USA||N 43° 58'||W 89° 32'||<500||8||yes||no||n/a|
|LL||Calvin||Michigan, USA||N 41° 50'||W 85° 57'||450 ± 10||8.5||no||no||n/a|
|SS||Ames||Oklahoma, USA||N 36° 15'||W 98° 12'||470 ± 30||16||no||yes||n/a|
|DD||Beaverhead||Montana, USA||N 44° 36'||W 113° 0'||~600||60||yes||no|
|GG||Holleford||Ontario, Canada||N 44° 28'||76° 38'||550 ± 100||2.35||no||yes||n/a|
|W||Sudbury||Ontario, Canada||N 46° 36'||W 81° 11'||1850± 3||250||yes||yes||wiki|
South America - Europe - Africa - Asia - Australia - Rocks in Space Home Page
I began this Earth Crater project back in the late 90’s, pre-google. The html has had some updates. 😉 And, most awesomely, there are 40 more earth crater discoveries since those days. Today, (Apr 2017) do find your details about earth impactors at
The Planetary and Space Science Center at The University of New Brunswick. You can use that database, combined with Wikipedia entries, and Google Earth, for an almost multi-media experience … you’ve got to love the 21st century!
The ways in which men came into the knowledge of things celestial appears to me almost as marvelous as the nature of these things themselves.
— Johannes Kepler
The impact of comets has profoundly influenced the story of life.
— Gene Shoemaker
Earth Craters Sorted by Continent
Happy Trails! Send me a postcard!
Moving Stars and Earth for Water event is a World premiere artistic event which will be presented via Live Webcast on ONE DROP’s website (http://www.onedrop.org) on October 9, at 8:00 p.m. EDT. (That’s 5:00 p.m. PDT)
After a year training and paying the $35 million ticket price, Guy Laliberte, first Canadian Space Tourist and Founder/CEO of Cirque du Soleil, launched from Baikonur to the Internationl Space Station on September 30. He arrived at ISS today, October 30, for two weeks aboard the orbiting station.
Facebook group: http://www.facebook.com/ONE.DROP.Foundation
June 27, 2008 NASA Jet Propulsion Laboratory firstname.lastname@example.org
The model of the JWST is on display in Washington DC. The US space agency Nasa has unveiled a model of a space telescope that scientists say will be able to see to the farthest reaches of the Universe. The James Webb Space Telescope (JWST) is intended to replace the aging Hubble telescope. It will be larger than its predecessor, sit farther from Earth and have a giant mirror to enable it to see more. Officials said the JWST – named after a former Nasa administrator – was on course for a launch in June 2013.
Written by Linda Vu, Spitzer Science Center
May 28, 2007
Large galaxy clusters are the universe’s metropolises, and for years many astronomers have focused their attention on the crowded “downtowns.” However, a new map of some of the largest ancient galactic cities shows that much of the “action” is happening in the cosmic suburbs.
Keep on reading!
Report Reveals Likely Causes of Mars Spacecraft Loss
WASHINGTON – After studying Mars four times as long as originally planned, NASA’s Mars Global Surveyor orbiter appears to have succumbed to battery failure caused by a complex sequence of events involving the onboard computer memory and ground commands.
The causes were released today in a preliminary report by an internal review board. The board was formed to look more in-depth into why NASA’s Mars Global Surveyor went silent in November 2006 and recommend any processes or procedures that could increase safety for other spacecraft.
Mars Global Surveyor last communicated with Earth on Nov. 2, 2006. Within 11 hours, depleted batteries likely left the spacecraft unable to control its orientation.
Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
“The loss of the spacecraft was the result of a series of events linked to a computer error made five months before the likely battery failure,” said board Chairperson Dolly Perkins, deputy director-technical of NASA Goddard Space Flight Center, Greenbelt, Md.
On Nov. 2, after the spacecraft was ordered to perform a routine adjustment of its solar panels, the spacecraft reported a series of alarms, but indicated that it had stabilized. That was its final transmission. Subsequently, the spacecraft reoriented to an angle that exposed one of two batteries carried on the spacecraft to direct sunlight. This caused the battery to overheat and ultimately led to the depletion of both batteries. Incorrect antenna pointing prevented the orbiter from telling controllers its status, and its programmed safety response did not include making sure the spacecraft orientation was thermally safe.
The board also concluded that the Mars Global Surveyor team followed existing procedures, but that procedures were insufficient to catch the errors that occurred. The board is finalizing recommendations to apply to other missions, such as conducting more thorough reviews of all non-routine changes to stored data before they are uploaded and to evaluate spacecraft contingency modes for risks of overheating.
“We are making an end-to-end review of all our missions to be sure that we apply the lessons learned from Mars Global Surveyor to all our ongoing missions,” said Fuk Li, Mars Exploration Program manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
Mars Global Surveyor, launched in 1996, operated longer at Mars than any other spacecraft in history, and for more than four times as long as the prime mission originally planned. The spacecraft returned detailed information that has overhauled understanding about Mars. Major findings include dramatic evidence that water still flows in short bursts down hillside gullies, and identification of deposits of water-related minerals leading to selection of a Mars rover landing site.
The Jet Propulsion Laboratory, Pasadena, Calif., manages Mars Global Surveyor for NASA’s Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft.
Information about the Mars Global Surveyor mission, including the preliminary report from the process review board and a list of some important discoveries by the mission, is available on the Internet at:
— Beth A. Biller is part of an international team of astronomers trying to tease out images of planets around young stars by removing the distortions caused by Earth’s atmosphere.
Extrasolar planets are extremely faint targets to begin with, and an atmospheric effect known as “speckling” has thwarted most previous attempts to observe them directly. Using instruments installed at the Very Large Telescope in Chile, Biller’s team has constructed some of the highest contrast images every obtained of substellar objects.
Her work is also helping determine requirements for NASA’s Terrestrial Planet Finder, a future mission that will directly observe and characterize habitable planets around nearby stars. Currently a doctoral candidate at the University of Arizona, she presented her research in an oral session at this year’s winter meeting of the American Astronomical Society. She is a native of the Washington, D.C., area.
MAUNA KEA (February 4, 2005) Astronomers using the Keck I telescope in Hawaii are learning much more about a strange, thermal ” hot spot” on Saturn that is located at the tip of the planet’s south pole. In what the team is calling the sharpest thermal views of Saturn ever taken from the ground, the new set of infrared images suggests a warm polar vortex at Saturn’s south pole — the first to ever be discovered in the solar system. This warm polar cap is home to a distinct compact hot spot, believed to contain the highest measured temperatures on Saturn. A paper announcing the results appears in the Feb. 4th issue of “Science.”
A ” polar vortex” is a persistent, large-scale weather pattern, likened to a jet stream on Earth that occurs in the upper atmosphere. On Earth, the Arctic Polar Vortex is typically located over eastern North America in Canada and plunges cold arctic air to the Northern Plains in the United States. Earth’s Antarctic Polar Vortex, centered over Antarctica,is responsible for trapping air and creating unusual chemistry, such as the effects that create the ” ozone hole.” Polar vortices are found on Earth, Jupiter, Mars and Venus, and are colder than their surroundings. But new images from the W. M. Keck Observatory show the first evidence of a polar vortex at much warmer temperatures. And the warmer, compact region at the pole itself is quite unusual.
” There is nothing like this compact warm cap in the Earth’s atmosphere,” aid Dr. Glenn S. Orton, of the Jet Propulsion Laboratory in Pasadena and lead author of the paper describing the results. ” Meteorologists have detected sudden warming of the pole, but on Earth, this effect is very short-term. This phenomenon on Saturn is longer-lived because we’ve been seeing hints of it in our data for at least two years.”
The puzzle isn’t that Saturn’s south pole is warm; after all, it has been exposed to 15 years of continuous sunlight, having just reached its summer Solstice in late 2002. But both the distinct boundary of a warm polar vortex some 30 degrees latitude from the southern pole and a very hot “tip” right at the pole were completely unexpected.
“ If the increased southern temperatures are solely the result of seasonality, then the temperature should increase gradually with increasing latitude, but it doesn’t,” added Dr. Orton. “ We see that the temperature increases abruptly by several degrees near 70 degrees south and again at 87 degrees south.”
The abrupt temperature changes may be caused by a concentration of sunlight-absorbing particulates in the upper atmosphere which trap in heat at the stratosphere. This theory explains why the hot spot appears dark in visible light and contains the highest measured temperatures on the planet. However, this alone does not explain why the particles themselves are constrained to the general southern part of Saturn and particularly to a compact area near the tip of Saturn’s south pole. Forced downwelling of relatively dry air would explain this effect, which is consistent with other observations taken of the tropospheric clouds, but more observations are needed.
More details may be forthcoming from an infrared spectrometer on the joint NASA/ESA Cassini mission which is currently orbiting Saturn. The Composite Infrared Spectrometer (CIRS) measures continuous spectral information spanning the same wavelengths as the Keck observations, but the two experiments are expected to complement each other. Between March and May in 2005, the CIRS instrument on Cassini will be able to look at the south polar region in detail for the first time. The discovery of the hot spot at Saturn’s south pole has prompted the CIRS science team, one of whom is Dr. Orton, to spend more time looking at this area.
” One of the obvious questions is whether Saturn’s north pole is anomalously cold and whether a cold polar vortex has been established there,” added Dr. Orton. “This is a question that can only be answered by the Cassini’s CIRS experiment in the near term, as this region can not be seen from Earth using ground-based instruments.”
Observations of Saturn were taken in the imaging mode of the Keck Long Wavelength Spectrometer (LWS) on February 4, 2004. Images were obtained at 8.00 microns, which is sensitive to stratospheric methane emission, and also at 17.65 and 24.5 microns, which is sensitive to temperatures at various layers in Saturn’s upper troposphere. The full image of the planet was mosaicked from many sets of individual exposures.
Future work observing Saturn will include more high-resolution thermal imaging of Saturn, particularly due to the fact that the larger polar vortex region may change in the next few years. The team has also discovered other phenomena which could be time dependent and are best characterized by imaging instruments at Keck, such as a series of east-west temperature oscillations, most prominently near 30 degrees south. These effects appear to be unrelated to anything in Saturn’s relatively featureless visible cloud system, but the variability is reminiscent of east-west temperature waves in Jupiter which move very slowly compared to the rapid jets tracked by cloud motions.
Funding for this research was provided by NASA’s Office of Space Sciences and Applications, Planetary Astronomy Discipline, and the NASA Cassini project. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C.
The W.M. Keck Observatory is operated by the California Association for Research in Astronomy, a non-profit scientific partnership of the California Institute of Technology, the University of California, and NASA.
April 20th, 2007
The Maple Leaf on Mars!
Canada will land on the surface of another planet for the first time when Phoenix, an international mission to Mars, touches down in 2008. Slated for launch on August 3, 2007, Phoenix will dig beneath Mars’s surface in search of ice – in search of life. Two Canadian instruments on board Phoenix will study Mars’s weather and climate to pave the way for future exploration missions.
Join the Canadian Space Agency’s Dr. Victoria Hipkin at the H.R. MacMillan Science Centre at 7:30 p.m. on Friday, April 20, 2007, for a special presentation on this exciting mission. Try a space science experiment at the Canadian Space Agency’s information booth. Learn everything you ever wanted to know about the Red Planet, and why the world’s scientists want to explore it.
The Phoenix mission is led by the University of Arizona, with Canadian expertise from a wide range of partners in universities and industry from many regions of the country: York University, the University of Alberta, Dalhousie University, the Geological Survey of Canada, MDA and Optech.
The conquest of space has been a dream of humans for centuries. Only in the last five decades however, have we had the technology to explore the cosmos. Until recently, this technology has been limited to only a few countries, including the United States, which leads the world. Lately though, Canada, too, has been gaining a foothold in space science.
Canadian scientists and engineers have made a series of important contributions to space missions, like Radarsat, the robotic Canadarms for the space shuttle and the International Space Station, and the MOST space telescope, just to name a few. Now, under the auspices of its own space agency, Canada is partnering with other countries to help explore the Red Planet. In its latest project, the Canadian Space Agency (CSA) is collaborating with NASA on its next Mars lander, called Phoenix, scheduled for launch in 2007. Hopes are high that the Canadian maple leaf will soon be seen on Mars.
As the Mars Program lead at CSA, Dr. Alain Berinstain (pictured above) acts as the link between the scientific community and research and development teams in government and industry. He is also responsible for science missions that explore the planets (including Mars), Mars-analog sites on Earth, and astronomy missions. Berinstain has a Bachelor’s degree in chemistry and biochemistry and a doctorate in chemistry, specializing in the effects of radiation on biological systems. As adjunct professor at University of Guelph, he also conducts research into environmental controls systems for greenhouses in extreme environments. We interviewed him via telephone last week.
For Release: February 21, 2007
NASA’s Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify signatures of molecules in their atmospheres. The landmark achievement is a significant step toward being able to detect possible life on rocky exoplanets and comes years before astronomers had anticipated.
“This is an amazing surprise,” said Spitzer project scientist Dr. Michael Werner of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We had no idea when we designed Spitzer that it would make such a dramatic step in characterizing exoplanets.”
Spitzer, a space-based infrared telescope, obtained the detailed data, called spectra, for two different gas exoplanets. Called HD 209458b and HD 189733b, these so-called “hot Jupiters” are, like Jupiter, made of gas, but orbit much closer to their suns.
They’re the Solar TerrEstrial RElations Observatories (STEREO… get it?), and they were lofted into orbit on October 25 http://www.universetoday.com/2007/01/25/first-images-of-the-sun-from-stereo/
It may be an asteroid or it may be a comet, but they are all Rocks from Space and some day one of those rocks WILL be too close to Earth!
ABLATION: Removal of material by heating and vaporization as a meteorite passes through Earth’s atmosphere.
ACHONDRITE: A class of stony meteorite formed by an igneous process; the lack of chondrules.
ALBEDO: the fraction of incident radiation, light, that is reflected by a surface. 1.0 = white, 0.0 = black
ALBEDO FEATURE: A dark or light marking on the surface of an object that may not be a geological or topographical feature.
ALLOCTHONOUS: Material that is formed or introduced from somewhere other than the place it is presently found. In impact cratering this may refer to the fragmented rock thrown out of the crater during its formation that either falls back to partly fill the crater or blankets it’s outer flanks after the impact event.
AMOR ASTEROIDS: A ‘Near Earth Asteroid’ which has a perihelion distance just beyond Earth orbit. 1.017 AU and 1.3 AU. Designation List
ANTIPODAL POINT: the point that is directly on the opposite side of the planet.
APHELION: the point in its orbit where a planet is farthest from the Sun.
APOLLO ASTEROIDS: A ‘Near Earth Asteroid’ which has a semimajor axes greater than 1.0 AU and perihelion distances less than 1.017 AU. Designation List
ASTEROID BELT: Between the orbits of Mars and Jupiter where most asteroids are located.
ASTEROID NUMBER: asteroids are assigned a serial number when they are discovered.
ASTEROIDS are small, mostly rocky bodies orbiting the Sun. Asteroids range in size from 1000 kilometers in orbit the Sun between Mars and Jupiter and are the source of most meteorites. They are classified into a number of types according to their spectra (and hence their chemical composition) and albedo (There are actually several classification schemes in use today.) There are also a dozen or so other rare types.
C-type, includes more than 75% of known asteroids: extremely dark (albedo 0.03); similar to carbonaceous chondrite meteorites; approximately the same chemical composition as the Sun minus hydrogen, helium, and other volatiles;
S-type, 17%: relatively bright (albedo .10-.22); metallic nickel-iron mixed with iron and magnesium silicates;
M-type, most of the rest: bright (albedo .10-.18); pure nickel-iron.
ASTROBIOLOGY: Study of the origin, distribution, and destiny of life in the universe.
ASTROBLEME: literally means “star wound” and refers to an ancient, eroded, meteoritic crater.
ASTRONOMICAL UNIT: (AU) 149,597,870.691 km; the average distance from the Earth to the Sun.
ATEN : asteroids that are always closer to the Sun than the Earth is; they have a period shorter than 1 year (the semi-major axis is smaller than Earth’s). Designation List
– b –
BARRINGER CRATER: also known as Meteor Crater, Arizona, USA.
BASALT: common volcanic igneous rock
BOLIDE: a fireball that produces a sonic boom
– c –
CALDERA: a crater formed by an explosion or by a collapsed volcanic vent
CARBON: An element with atomic number 6; symbol: C. Carbon is one of the four elements essential for life. (The others are hydrogen, oxygen, and nitrogen.)
CARBONATE: A compound containing carbon and oxygen.
CATACLASTIC: A texture found in metamorphic rocks in which brittle minerals have been broken, crushed, and flattened during shearing.
CATENA: A chain of craters.
CAVUS: Hollow, irregular depression.
CENTAURS : A diverse group of rocks in the outer solar system that displays episodic cometary behavior and eccentric orbits. Centaurs are objects that probably came from the Kuiper belt.(also a class of rocket). The plot of the outer solar system.
CENTRAL PEAK: The exposed core of uplifted rocks in complex meteorite impact craters. The central peak material typically shows evidence of intense fracturing, faulting, and shock metamorphism.
CERES: The largest and first discovered (1801) asteroid in the Asteroid Belt.
CHAOS: distinctive area of broken terrain.
CHICXULUB CRATER: The submerged crater at the tip of the Yucatán Peninsula is an impact crater that dates from 65 million years ago. It is 120 miles wide and 1 mile deep. It is probably the site of the K-T meteorite or comet impact that caused the extinction of the dinosaurs and other groups of organisms.
CHONDRITE: A common type of meteorite that contains chondrules (see definition below). Chondrites come from asteroids that did not melt when formed and are designated as H, L, LL, E, or C depending on chemical compositions. The H, L, and LL types are called ordinary chondrites. The L chondrites are composed of silicate minerals (mostly olivine and pyroxene, but feldspar as well), metallic nickel-iron, and iron sulfide (called troilite). Most L chondrites are severely shocked-damaged, probably by a large impact on the asteroid in which they formed. The C (or carbonaceous) chondrites are the most primitive meteorites. They contain water-bearing minerals and carbon Compounds including a variety of organic molecules such as amino acids.
CHONDRULE : Roughly spherical objects found in a type of meteorite called chondrites. Most chondrules are 0.5 to 2 millimeters in size and are composed of olivine and pyroxene, with smaller amounts of glass and iron-nickel metal. The shapes of the mineral grains in them indicate that chondrules were once molten droplets floating freely in space.
COMA: The dust and gas surrounding an active comet’s nucleus
COMET: A medium-sized icy object orbiting the Sun; smaller than a planet. It is made up of a nucleus (solid, frozen ice, gas and dust), a gaseous coma (water vapor, CO2, and other gasses) and a tail (dust and ionized gasses). Because of the force of the solar wind its long tail of gas and dust always points away from the sun, The tail can be up to 250 million km long. Comets are only visible when they’re near the sun in their highly eccentric orbits.
COMMENSURATE ORBITS: Asteroid orbits whose periods are simple multiples or fractions of Jupiter’s orbital period.
COMPLEX IMPACT CRATER: A large crater with a single or many peaks in the middle of the crater. Examples are found on the Moon and on Earth.
COSMIC DUST: Microscopic silicate or iron particles. IPD’s (Interplanetary dust particles) can collect in buried mud, the atmosphere, or in space. Smaller than the dust-like particles we see burning up during a meteor shower. Cosmic Dust originates withing comets and asteroids, and perhaps in the solar nebula. The dust may be carbon-rich, and may have provided an source of organic material for early Earth.
COSMIC RAY EXPOSURE AGE: An age determined by the presence of specific isotopes produced by cosmic ray bombardment.
COSMIC VELOCITY: The velocity of an orbiting body in space.
CRATER: Bowl shaped depression caused by impact or a depression around a volcanic vent.
CRATER RAYS: Lines of ejecta radiating from a crater.
CRATON : The stable portions of continents composed of shield areas and platform sediments. Typically cratons are bounded by tectonically active regions characterized by uplift, faulting, and volcanic activity.
CRETACEOUS PERIOD: A geological term denoting the interval of Earth history beginning around 144 million years ago and ending 66 million years ago with the Chixalub impact and the demise of the age of dinosaurs.
CRYSTALLINE : – Rock types made up of crystals or crystal fragments, such as metamorphic rocks that recrystallized in high-temperature or pressure environments, or igneous rocks that formed from cooling of a melt. Crystallization; the formation of minerals with an ordered atomic crystalline structure.
CRYSTAL LATTICE: An orderly arrangement of atoms in a mineral.
DENSITY: measured in grams per cubic centimeter (or kilograms per liter); the density of water is 1.0; iron is 7.9; lead is 11.3.
DIAPLECTIC GLASS: A natural glass formed by shock pressure from any of several minerals without melting. It is found only in association with meteorite impact craters.
DIFFERENTIATION: Chemical zonation caused by differences in the densities of minerals; heavy materials sink, less dense materials float.
DINOSAURS: large reptiles that lived until 65 million years ago. Most probably wiped out by an impact.
DISASTER: From the greek “dis” and “aster”, the opposite of a sprinkle of light (stars).
– e –
EARTH GRAZER: A meteoroid (or other space debris) that enters the Earth’s atmosphere and disintegrates, traveling nearly parallel to Earth’s surface
ECCENTRICITY: The astronomical measurement describing an orbit’s deviation from the circular.
EJECTA: Material thrown out from and deposited around an impact crater.
ELLIPSE: oval. the orbits of the planets are ellipses, not circles.
ENERGY: The capacity for doing work. Energy can change from one form (heat, chemical, nuclear, potential energy) into another but is always conserved.
EON: Two or more geological Eras form an Eon, which is the largest division of geological time, lasting hundreds of millions of years.
EPOCH: A division of a geologic period; it is the smallest division of geologic time, lasting several million years.
– f –
FACULA: Bright spot. For example, the Memphis Facula around bright region of Ganymede, a moon of Jupiter.
FALLS: Rare, a rock found as the result of an ‘observed’ meteorite impact.
FINDS : The majority of meteorites are recorded as finds, those specimens which were not observed to fall.
FIREBALL: a meteor brighter than magnitude -3 caused by millimeter-sized (or bigger) meteoroids disintegrating in the atmosphere.
FISSURE: a narrow opening or crack of considerable length and depth.
FRACTIONATION: Fractional crystallization: a process in which minerals crystallize out of a magma at specific temperatures, thereby changing the composition of the magma.
– g –
GEOCENTRIC DISTANCE: The distance from Earth.
GEOLOGIST: Scientist who studies Earth, its materials, the physical and chemical changes that occur on the surface and in the interior, and the history of the planet and its life forms. Planetary geologists extend their studies to the Moon, planets, and other solid bodies in the Solar System.
GEGENSCHEIN: Faint, diffuse, glowing region on the ecliptic opposite of the Sun produced by IDP’s (interplanetary dust particles)
– h –
HEXAHEDRITE: An iron meteorite containing less than 5 percent nickel.
HIGH-PRESSURE MINERAL PHASES: Mineral forms that are stable only at the extremely high pressures typical of Earth’s deep interior but not its surface. Such pressures are generated instantaneously during meteorite impact. For example, stishovite is the high-pressure polymorph of quartz, a common crustal mineral.
– i –
ICE: In planetary science, terms refers to water, methane, and ammonia which usually occur as solids in the outer solar system.
IGNEOUS ROCK: When molten rock cools, igneous rock is formed.
IMPACT BASIN: An impact crater that has a rim diameter greater than 185 miles (300 km). There are over 40 impact basins on the Moon. These catastrophic impacts produce faulting and other crust deformations.
IMPACT CRATER: What remains of collisions between an asteroid or meteorite and a planet or moon.
IMPACTITES: A collective term for all rocks being affected by impact as the result of a collision with another planetary body.
IMPACT MELT: Rocks melted during impact. They are extremely uniform in their composition but variable in their texture. They are composed predominantly of the target rocks but may contain a small amount of the impactor.
IMPACT SHOCK: Rocks shocked during impact. Usually seen in quartz minerals.
INCLINATION: the angle between the plane of its orbit and the ecliptic.
– k –
KILOGRAM: (kg) = 1000 grams = 2.2 pounds, the mass of a liter of water.
KILOMETER: kilometer (km) = 1000 meters = 0.62 miles.
KINETIC ENERGY: Kinetic energy is the energy that an object has because of its motion. An object’s kinetic energy is equal to 0.5 times its mass times its velocity squared. In the metric system, kinetic energy is measured in joules or kg-m2/s2.
KIRKWOOD GAPS: relatively empty regions between the main concentrations of asteroids in the Main Asteroid Belt
KUIPER BELT OBJECTS: a disk-shaped region past the orbit of Neptune containing at least 70,000 small icy bodies. It is now considered to be the source of the short-period comets. The Kuiper belt was named after the Dutch-American astronomer Gerard P. Kuiper, who predicted its existence in 1951.
– l –
LIGHT-YEAR: = 9.46053e12 km (= 5,880,000,000,000 miles = 63,239 AU); the distance traveled by light in a year.
LIMB: the outer edge of the apparent disk of a celestial body
– m –
MACULA: dark spot.
MAGMA: Molten rock containing dissolved minerals and gasses which crystallize out to form igneous rock.
MANTLE: A zone in a differentiated parent body between the core and the crust.
MAGNITUDE: The degree of brightness of a celestial body designated on a numerical scale, on which the brightest star has magnitude -1.4 and the faintest visible star has magnitude 6, with the scale rule such that a decrease of one unit represents an increase in apparent brightness by a factor of 2.512. Also called apparent magnitude.
MAIN BELT: located between Mars and Jupiter roughly 2 – 4 AU from the Sun; further divided into subgroups: Hungarias, Floras, Phocaea, Koronis, Eos, Themis, Cybeles and Hildas (which are named after the main asteroids in the group).
MARIA: Large impact basins on the Moon filled with basalts.
METEOR: Also “shooting star.” The light from an object, as small as a grain of dust, as it burns through Earth’s atmosphere. Larger rocks, that give off more light, are known as bolides or fireballs.
METEORITE: A rock of extra-terrestrial origin found on Earth
METEOROID: A small rocky object orbiting the Sun; smaller than an asteroid
– n –
NEAs: (Near Earth Asteroids) are asteroids which have orbits that bring them within 121 million miles or 195 million kilometers (1.3 A.U.) of the Sun. There are over 250 near-Earth asteroids known and they are classified into three groups: Atens, Apollos, and Amors. NEA’s are the only asteroids that can crash into our planet.
NEAT: (Near-Earth Asteroid Tracking) is a NASA/JPL system that tracks near-earth asteroids using the 1.2-meter- diameter (48-inch) Palomar telescope to track asteroids that come close to the Earth.
NECs: (Near Earth Comets) Short-period comets (period less than 200 years) with orbits that bring them within 121 million miles or 195 million kilometers (1.3 A.U.) of the Sun.
– o –
OLD: a planetary surface that has been modified little since its formation typically featuring large numbers of impact craters
OORT CLOUD: the spherical cloud of rock and debris, about six trillion icy objects, surrounding our planetary system which extends approximately 3 light years, approximately 30 trillion, kilometers from the Sun.
– p –
PARSEC: = 206265 AU = 3.26 light year
PEAK RING: Central uplift characterized by a ring of peaks rather than a single peak. Peak rings are typical of larger terrestrial craters above about 50 km in diameter.
PERIHELION: The point in the path of a celestial body that is nearest to the sun.
PERIOD: The time it takes a rock to orbit the sun. For example: long period comets >200 years and short period comets < 200 years.
PERTURB: To cause a planet or satellite to deviate from a theoretically regular orbital motion.
PHAs (Potentially Hazardous Asteroids) MOID=0.05 A.U. (Minimum Orbital Insertion Distance) These rocks may never impact Earth but their closeness is worth a sharp watch. There are over 200 known PHA’s. (link includes daily orbital elements and tables of known PHA’s and further info) See Torino Impact Scale.
PLANAR FEATURES: Microscopic features in grains of quartz or feldspar consisting of very narrow planes of glassy material arranged in parallel sets that have distinct orientations with respect to the grain’s crystal structure.
– r –
RESOLUTION: the amount of small detail visible in an image; low resolution shows only large features, high resolution shows many small details.
– s –
SEMIMAJOR AXIS: the semimajor axis of an ellipse (e.g. a planetary orbit) is 1/2 the length of the major axis which is a segment of a line passing thru the foci of the ellipse with endpoints on the ellipse itself. The semimajor axis of a planetary orbit is also the average distance from the planet to its primary. The periapsis and apoapsis distances can be calculated from the semimajor axis and the eccentricity by rp = a(1-e) and ra = a(1+e).
SHATTER CONE: Striated conical fracture surfaces produced by meteorite impact into fine-grained brittle rocks such as limestone.
SHIELD: Any of several extensive regions where ancient Precambrian crystalline rocks are exposed at the Earth’s surface, for example, the Canadian Precambrian Shield
SHOCKED QUARTZ: Quartz that has undergone deformation due to extreme pressure and heat. It has been found in the layer that marks the K-T boundary.
SHOCK METAMORPHISM: The production of irreversible chemical or physical changes in rocks by a shock wave generated by impact, or detonation of high-explosive or nuclear devices.
SHOEMAKER, Gene: Pioneered the field of impact cratering with his landmark studies of Barringer Crater (a.k.a. Meteor Crater) in Arizona, and as a chief geologist he taught the Apollo astronauts about rocks on the moon. Also a pioneer of theories of impact-induced mass extinctions in the geologic past, and the search for Earth-crossing asteroids and comets. He and his wife Carolyn and David Levy were the team that discovered the famed comet that smacked into Jupiter in 1994.
SHOEMAKER-LEVY 9: SL-9 was a short-period comet that was discovered by Eugene and Carolyn Shoemaker and David H. Levy. As the comet passed close by Jupiter, Jupiter’s gravitational forces broke the comet apart. Fragments of the comet collided with Jupiter for six days during July 1994, causing huge fireballs in Jupiter’s atmosphere that were visible from Earth.
SHORT PERIOD COMETS (SPC): are those comets with a period less than 200 years
SIDEROPHILE ELEMENTS: An element with a weak affinity for oxygen and sulfur such as iridium, osmium, platinum, and palladium, that, in chemically segregated asteroids and planets, are found in the metal-rich interiors. Consequently, these siderophile elements are extremely rare on Earth’s surface.
SI UNITES 1564-1616 SI is an abbreviation for systeme internationale, which has become the worldwide adopted standard for units of measurement.
SILICATE: a compound containing silicon and oxygen (e.g. olivine)
STISHOVITE: A dense, high-pressure phase of quartz that has so far been identified only in shock-metamorphosed quartz-bearing rocks from meteorite impact craters.
– t –
TARGET ROCKS: The surface rocks that an asteroid or comet impactor smashes into in an impact event.
TORINO IMPACT SCALE: Developed in 1999, a scale which describes the risks of a threat of any NEO.
TROJANS: located near Jupiter’s Lagrange points (60 degrees ahead and behind Jupiter in its orbit). Several hundred such asteroids are now known; it is estimated that there may be a thousand or more. This name derives from a generalization of the names of two of the largest asteroids in Jupiter’s Lagrange points: 624 Hektor and 911 Agamemnon. Saturn’s satellites are also sometimes called Trojans.
TECTONIC: deformation forces acting on a planet’s crust.
TEKTITES: Natural, silica-rich, homogeneous glasses produced by complete melting and dispersed as droplets during terrestrial impact events. They range in color from black or dark brown to gray or green and most are spherical in shape. Tektites have been found in four regional deposits or “strewn fields” on the Earth’s surface: North America, Czechoslovakia (the moldavite tektites), Ivory Coast, and Australasia.
– v –
VELOCITY: Both the speed and the direction that a body is moving. It has more information than speed alone. Velocity is a vector
– y –
“Today, thanks to the pioneering asteroid survey Spacewatch and similar projects, our planetary system appears as a humming hive populated with countless asteroids circling the sun like a swarm of bees.” — Space Daily
Classifications of Space Rocks
1 AU = 1 Astronomical Unit = 93 million miles = 149 million kilometers
Inclination = degrees from the elliptic plane of the solar system, like that swarm of bees.
|Trojan minor planets||
Mineralogically, meteorites consist of varying amounts of nickel-iron alloys, silicates, sulfides, and several other minor phases. Classification is then made on the basis of the ratio of metal to silicate present in the various compositions. No two meteorites are completely alike, and specific compositional and structural features give a particular meteorite its unique identity.
Rare, (est. only 5%) characterized by the presence of two nickel-iron alloy metals: kamacite and taenite, combined with minor amounts of non-metallic phases and sulfide minerals, form three basic subdivisions of irons. Depending upon the percentage of nickel to iron, these subdivisions are classified as:
Achondrite Meteorites –Millbillillie
Consist of almost equal amounts of nickel-iron alloy and silicate minerals. Although all stony-irons may not be genetically related or have similar composition, they are combined into one group and divided into two subgroups for convenient classification. The Pallasite group is characterized by olivine crystals surrounded by a nickel-iron structure which forms a continuous enclosing network around the silicate portion. Mesosiderites, on the other hand, consist mainly of plagioclase and pyroxene silicates in the form of heterogeneous aggregates intermixed with the metal alloy. No distinct separation between the metal and silicate phases is readily apparent as it is with the Pallasites.
100.3 grams of
The most abundant of the three meteorite groups and come closest to resembling earth rocks in their appearance and composition. The major portion of these meteorites consists of the silicate minerals olivine, pyroxene, and plagioclase feldspars. Metallic nickel-iron occurs in varying percentages and is accompanied by an iron-sulfide mineral. Aside from
"Nowadays, of course, the politically correct
way to group organisms, especially prokaryotes, is on a genetic basis,
i.e., by comparison of the nucleotide sequences of the small subunit ribosomal
RNA that is contained in all cellular organisms."
1997 Kenneth Todar University of Wisconsin-Madison Department of Bacteriology
Barthel, K.W., Swinburne, N.H.M., and Conway Morris,
S. 1994. Solnhofen: A Study in Mesozoic Palaeontology. Cambridge University Press, Cambridge.
David H. Levy, "Comets: Creators and Destroyers"
Touchstone Books, 1998
Frank Press, Raymond Siever, "Earth" W.H. Freeman
and Co., 1986
Oxford Dictionary of Quotations, Oxford Press, 1953
Robert H. Dott, Jr., Roger L. Batten, "Evolution of the Earth" Second Edition, McGraw Hill, 1976
David Lambert, "The Dinosaur Data Book". 1991
A. Lee McAlester, "The History of Life", Second Edtion, 1977
Monastersky, R., "Eruptions Cleared Path for Dinosaurs"
Science News, 04/24/99, Vol. 155 Issue 17, p260
Global Earth History Paleo maps
April 20, 2001
Earthshine Rocks in Space
Earth Craters, Europe
This is: European Impact Craters
|BB||Ilumetsa||Estonia||N 57° 58'||E 27° 25'||0.002||0.08||yes||yes||n/a|
|O||Kaalijärvi||Estonia||N 58° 24'||W 111° 1'||0.004 ± 0.001||0.11||yes||yes||n/a|
|E||Morasko||Poland||N 52° 29'||W 102° 29'||0.01||0.1||yes||yes||n/a|
|U||Karikkoselkä||Finland||N 63° 13'||E 25° 15'||<1.88||1.5||yes||yes||n/a|
|HH||Karla||Russia||N 54° 54'||E 48° 0'||<10||12||yes||no||n/a|
|C||Steinheim||Germany||N 48° 41'||E 10° 4'||15 ± 1||3.8||yes||yes||n/a|
|D||Ries||Germany||N 48° 53'||E 10° 37'||15 ± 1||24||yes||yes||n/a|
|A||Azuara||Spain||N 41° 10'||W 0° 55'||~40||30||yes||no||n/a|
|EE||Logoisk||Belarus||N 54° 12'||E 27° 48'||40 ± 5||17||no||no||n/a|
|Kamensk||Russia||N 48° 20'||E 40° 15'||49 ± 0.2||25||no||no||n/a|
|T||Lappajärvi||Finland||N 63° 12'||E 23° 42'||77.3 ± 0.4||23||yes||yes||n/a|
|LL||Boltysh||Ukraine||N 48° 45'||E 32° 10'||88 ± 3||24||no||no||n/a|
|K||Dellen||Sweden||N 61° 48'||E 16° 48'||89 ± 2.7||19||no||yes||n/a|
|JJ||Zapadnaya||Ukraine||N 49° 44'||E 29° 0'||115 ± 10||4||no||no||n/a|
|OO||Zeleny Gai||Ukraine||N 48° 42'||E 32° 54'||120 ± 20||2.5||no||no||n/a|
|F||Mien||Sweden||N 56° 25'||E 14° 52'||121 ± 2.3||9||yes||no||n/a|
|MM||Rotmistrovka||Ukraine||N 49° 0'||E 32° 0'||140 ± 20||2.7||no||no||n/a|
|Z||Mjølnir||Norway||N 73° 48'||E 29° 40'||143 ± 20||40||no||yes||n/a|
|CC||Vepriai||Lithuania||N 55° 10'||E 24° 34'||>160 ± 30||8||no||no||n/a|
|GG||Puchezh-Katunki||Russia||N 57° 6'||E 43° 35'||175 ± 3||80||no||no||n/a|
|B||Rochechouart||France||N 45° 50'||E 0° 56'||214 ± 8||23||yes||no||n/a|
|NN||Obolon'||Ukraine||N 49° 30'||E 32° 55'||215 ± 25||15||no||no||n/a|
|II||Kursk||Russia||N 51° 40'||E 36° 0'||250 ± 80||5.5||no||no||n/a|
|AA||Mishina Gorna||Russia||N 58° 40'||E 28° 0'||<360||4||yes||no||n/a|
|M||Dobele||Latvia||N 56° 35'||E 23° 15'||300 ± 35||4.5||no||no||n/a|
|PP||Ternovka||Ukraine||N 48° 1'||E 33° 5'||350||15||no||no||n/a|
|J||Siljan||Sweden||N 61° 2'||E 14° 52'||368 ± 1.1||52||yes||yes||n/a|
|FF||Kaluga||Russia||N 54° 30'||E 36° 15'||380 ± 10||15||no||no||n/a|
|KK||Ilyinets||Ukraine||N 49° 7'||E 29° 6'||395 ± 5||4.5||no||no||n/a|
|N||Kärdla||Estonia||E 22° 40''||W 74° 30'||455||4||no||no||n/a|
|I||Tvären||Sweden||N 58° 46'||E 17° 25'||>455||2||no||no||n/a|
|L||Lockne||Sweden||N 63° 0'||E 14° 48'||>455||7.5||no||no||n/a|
|H||Granby||Sweden||N 58° 25'||E 14° 56'||470||3||no||no||n/a|
|G||Gardnos||Norway||N 60° 39'||E 9° 0'||500 ± 10||5||yes||no||n/a|
|R||Sääksjärvi||Finland||N 61° 24'||E 22° 24'||~560||6||yes||no||n/a|
|DD||Mizarai||Lithuania||N 54° 1'||E 24° 0'||570 ± 50||5||no||no||n/a|
|X||Jänisjärvi||Russia||N 61° 58'||E 30° 55'||698 ± 22||14||yes||yes||n/a|
|S||Söderfjärden||Finland||N 62° 54'||E 21° 42'||~600||5.5||no||no||n/a|
|V||Suvasvesi N||Finland||N 62° 42'||E 28° 0''||<1000||4||yes||no||n/a|
|Q||Lumparn||Finland||N 60° 9'||E 20° 6'||~1000||9||no||no||n/a|
|W||so-Naakkima||Finland||N 62° 11'||E 27° 9'||>1000||3||no||no||n/a|
|Y||Suavjarvi||Russia||N 63° 7'||E 33° 23'||2400||16||yes||no||n/a|
|P||Neugrund||Estonia||N 59° 20'||E 23° 40'||Unknown||6 to 8||no||no||n/a|
"The impact of comets has profoundly influenced the story of life." -- Gene Shoemaker
The impact of comets has profoundly influenced the story of life."
Gene Shoemaker’s life’s work in papers and abstracts is an awesome contribution to the study of astrogeology. Unfortunately, a list doesn’t convey the inspiration he passed around among friends and colleagues.
1. Shoemaker, E.M., 1951, Internal structure of the Sinbad
2. Shoemaker, E.M., 1953, Collapse origin of the diatremes of the
3. Shoemaker, E.M., and Newman, W.L., 1953, Ute Mountains, a laccolithic
4. Shoemaker, E.M., 1956, Unusual folds in Moenkopi Formation around
5. Shoemaker, E.M., Newman, W.L., and Miesch, A.T., 1956, Sources of the
6. Shoemaker, E.M., 1957, Primary structures of maar rims and their
7. Miesch, A.T., Shoemaker, E.M., Newman, W.L., and Finch, W.I., 1958,
8. Miesch, A.T., Shoemaker, E.M., Newman, W.L., and Finch, W.I., 1958,
9. Shoemaker, E.M., 1959, Structure and Quaternary stratigraphy of Meteor
10. Shoemaker, E.M., and Chao, E.C.T., 1960, Origin of the Ries Basin,
11. Shoemaker, E.M., and Hackman, R.J., 1960, Stratigraphic basis for a
12. Shoemaker, E.M., 1961, Interplanetary correlation of geologic time
13. Eggleton, R.E., and Shoemaker, E.M., 1962, Breccia at Sierra Madera,
14. Chao, E.C.T., Shoemaker, E.M., and Madsen, B.M., 1962, First natural
15. Shoemaker, E.M., 1962, Sampling the moon through Kordylewski’s clouds:
16. Gault, D.E., Shoemaker, E.M., and Moore, H.J., 1962, The flux and
17. Shoemaker, E.M., and Elston, D.P., 1963, Structure and history of the
18. Shoemaker, E.M., 1963, Astrogeology, a new horizon (abs.), in
19. Shoemaker, E.M., 1966, Structure of the Jangle U and Teapot Ess
20. Shoemaker, E.M., and Lowery, C.J., 1966, Airwaves associated with
21. Shoemaker, E.M., and Stephens, H.G., 1969, The Green and Colorado
22. Shoemaker, E.M., Lucchitta, Ivo, and Foley, M.G., 1971, Collapse of
23. Shoemaker, E.M., 1971, Why explore the geology of Mars (abs.):
24. Shoemaker, E.M., Jackson, E.D., and Hait, M.H., 1971, Surficial and
25. Shoemaker, E.M., 1972, Cratering history and early evolution of the
26. Helsley, C.E., and Shoemaker, E.M., 1973, Magnetostratigraphy of the
27. Purucker, M.E., and Shoemaker, E.M., 1973, Remarkable episode of
28. Shoemaker, E.M., Elston, D.P., and Helsley, C.E., 1973, Depositional
29. Shoemaker, E.M., Squires, R.L., and Abrams, M.J., 1973, The Bright
30. Shoemaker, E.M., and Purucker, M.E., 1974, “Gray Mountain”
31. Shoemaker, E.M., 1975, Late Cenozoic faulting and uplift of the
32. Shoemaker, E.M., and Helin, E.F., 1976, An Empirical test of Opik’s
33. Shoemaker, E.M. and Helin, E.F., 1976, Systematic search for
34. Champion, D.E., and Shoemaker, E.M., 1977, Paleomagnetic evidence for
35. Helin, E.F., and Shoemaker, E.M., 1977, 1976 UA: Second Asteroid with
36. Kellogg, J.N., and Shoemaker, E.M., 1977, Age determination of
37. Shoemaker, E.M., and Helin, E.F., 1977, Present impact cratering rates
38. Steiner, M.B., Shive, P.N., and Shoemaker, E.M., 1977, Polarity of the
39. Champion, D.E., Gromme, C.S., and Shoemaker, E.M., 1978, Holocene
40. Helin, E.F., Shoemaker, E.M., and Wolfe, R.F., 1978, Ra-Shalom: Third
41. Shoemaker, E.M., 1978, Search for near-Earth asteroids (abs.), in
42. Shoemaker, E.M., and Helin, E.F., 1978, Near-Earth asteroids as
43. Shoemaker, E.M., Squires, R.L., and Abrams, M.J., 1978, The Bright
44. Shoemaker, E.M., 1979, Geology and history of Ganymede and Callisto
45. Shoemaker, E.M., 1979, Geology of Ganymede (ext. abs.): National
46. Shoemaker, E.M., and Passey, Q.R., 1979, Tectonic history of Ganymede
47. Shoemaker, E.M., Williams, J.G., Helin, E.F., and Wolfe, R.F., 1979,
48. Passey, Q.R., and Shoemaker, E.M., 1980, Global distribution of
49. Passey, Q.R., Shoemaker, E.M., and McCauley, J.F., 1980, Craters and
50. Plescia, J.B., Boyce, J.M., and Shoemaker, E.M., 1980, Ganymede
51. Plescia, J.B., Boyce, J.M., and Shoemaker, E.M., 1980, Ganymede
52. Plescia, J.B., Shoemaker, E.M., and Boyce J.M., 1980, The cratering of
53. Plescia, J.B., Shoemaker, E.M., and Boyce, J.M., 1980, The cratering
54. Shoemaker, E.M., 1980, Geologic history of Ganymede (abs.), in
55. Shoemaker, E.M., Bus. S.J., Williams, J.G., and Helin, E.F., 1980,
56. Shoemaker, E.M., Helin, E.F., Bus. S.J., and Passey, Q.R., 1980, New
57. Shoemaker, E.M., and Wolfe, R.F., 1980, Comets and the Galilean
58. Wenrich-Verbeek, K.J., and Shoemaker, E.M., 1980, Uranium
59. Degewij, J., Shoemaker, E.M., Wolfe, R.F., 1981, Low activity comets
60. Passey, Q.R., and Shoemaker, E.M., 1981, Age of Callisto’s surface,
61. Passey, Q.R., Shoemaker, E.M., 1981, Ganymedian thermal gradients from
62. Shoemaker, E.M., 1981, Collision of asteroids and comets with planets
63. Shoemaker, E.M., 1981, Crustal evolution of Callisto and Ganymede
64. Shoemaker, E.M., 1981, The icy satellites of Saturn (abs.): EOS,
65. Shoemaker, E.M., 1981, Impact record of the planets and satellites
66. Shoemaker, E.M., Shoemaker, C.S., Helin, E.F., Bus, S.J., and Wolfe,
67. Shoemaker, E.M., and Wolfe, R.F., 1981, Evolution of the Saturnian
68. Bus, S.J., Helin, E.F., Dunbar, R.S., and Shoemaker, E.M., Dawe, J.,
69. Cook, A.F., Shoemaker, E.M., Soderblom, L.A., Mullins, K.F., and
70. Gehrels, T., McMillan, R., Frecker, J., Roland, E., Stoll, C., Doose,
71. Passey, Q.R., and Shoemaker, E.M., 1982, Early thermal histories of
72. Shoemaker, E.M., 1982, Bombardment of the Earth from late stages of
73. Andrews, R.S., and Shoemaker, E.M., 1983, Continental Scientific
74. Shoemaker, E.M., 1983, Impacts and extinctions; a planetary
75. Shoemaker, E.M., and Herkenhoff, K.E., 1983, Impact origin of Upheaval
76. Shoemaker, E.M., Pillmore, C.L., Tshudy, R.H., and Orth, C.J., 1983,
77. Wolfe, R.F., Degewij, J., Shoemaker, E.M., 1983, The perihelion
78. Shoemaker, E.M., Bus, S.J., Dunbar, R.S., Helin, E.F., Dawe, J.,
79. Shoemaker, E.M., and Herkenhoff, K.E., 1984, Upheaval Dome impact
80. Shoemaker, E.M. and Shoemaker, C.S., 1984, Survey for Mars-crossing
81. Shoemaker, E.M., Steiner, M.B., Fassett, J.E., and Tschudy, R. H.,
82. Shoemaker, E.M.,and Wolfe, R.F., 1984, Evolution of the Uranus-Neptune
83. Shoemaker, E.M., and Wolfe, R.F., 1984, Crater ages, comet showers,
84. Tanaka, K.L., Ulrich, G.E., and Shoemaker, E.M., 1984,
85. Gillett, S.L., Kirschrink, J.L., Van Alstine, D.R., Lewis, R.E., and
86. Hut, P., Alvarez, W., Elder, W., Hansen, T.A., Keller, G., Shoemaker,
87. Keller, G., D’Hondt, S., Onstott, T., Orth, C.J., Gilmore, G.S.,
88. Shoemaker, E.M., and Shoemaker, C.S., 1985, Impact structures of
89. Bus, S.J., Bowell, E., Shoemaker, E.M., and Kowal, C.T., 1986,
90. Harris, A.W., and Shoemaker, E.M., 1986, Asteroid and comet collision:
91. Shoemaker, E.M., 1986, Hazards of asteroid and comet collision with
92. Shoemaker, E.M., 1986, Satellites of Uranus (abs.): Geological Society
93. Shoemaker, E.M., 1986, Geologic history of the Uranian satellites
94. Shoemaker, E.M., and Shoemaker, C.S., 1986, Connolly Basin, a probable
95. Shoemaker, E.M., Wolfe, R.F., and Shoemaker, C.S., 1986, Extinct
96. Shoemaker, E.M., Wolfe, R.F., Bus, S.J., and Williams, J.G., 1986,
97. Schaber, G.G., Shoemaker, E.M., and Kozak, R.C., 1987, Is the Venusian
98. Schaber, G.G., Shoemaker, E.M., and Kozak, R.C., 1987, The surface age
99. Schaber, G.G., Shoemaker, E.M., and Wolfe, R.F., 1987, The
100. Shoemaker, E.M., and Ostro, S.J., 1987, Thermally annealed ejecta in
101. Shoemaker, E.M., and Shoemaker, C.S., 1987, Meteorite craters of
102. Shoemaker, E.M., and Shoemaker, C.S., 1987, Observations on the
103. Shoemaker, E.M., and Wolfe, R.F., 1987, Crater production on Venus
104. Champion, D.E., Lanphere, M.A., and Shoemaker, E.M., 1988, Multiple
105. Roddy, D.J., Shoemaker, E.M., Shoemaker, C.S., and Roddy, J.K., 1988,
106. Shoemaker, C.S., and Shoemaker, E.M., 1988, The Palomar asteroid and
107. Shoemaker, E.M., 1988, Solar system roulette: Asteroid strikes and
108. Shoemaker, E.M., Roddy, D.J., Shoemaker, C.S., and Roddy, J.K., 1988,
109. Shoemaker, E.M., and Shoemaker, C.S., 1988, Impact structures of
110. Shoemaker, E.M., and Shoemaker, C.S., 1988, The Spider impact
111. Shoemaker, E.M., and Shoemaker, C.S., Wolfe, R.F., 1988, Asteroid and
112. Nishiizumi, K., Kohl, C.P., Shoemaker, E.M., Arnold, J.R., Lal, D.,
113. Shoemaker, E.M., and Shoemaker, C.S., 1989, Geology of the Connolly
114. Shoemaker, E.M., Shoemaker, C.S., and Plescia, J.B., 1989, Gravity
115. Shoemaker, E.M., Shoemaker, C.S., and Wolfe, R.F., 1989, Asteroid and
116. Williams, J.G., Shoemaker, E.M., and Wolfe, R.F., 1989, Structure in
117. Bowell, E., Holt, H.E., Levy, D.H., Innanen, K.A., Mikkola, S., and
118. Shoemaker, C.S., and Shoemaker, E.M., 1990, Survey for bright Trojan
119. Shoemaker, C.S., Shoemaker, E.M., and Wolfe, R.F., 1990,
120. Shoemaker, E.M., and Shoemaker, C.S., 1990, Proterozoic impact record
121. Shoemaker, E.M., Shoemaker, C.S., Nishiizumi, K., Kohl, C.P., Arnold,
122. Shoemaker, E.M., Shoemaker, C.S., Wolfe, R.F., and Holt, H.E., 1990,
123. Shoemaker, E.M., Shoemaker, C.S., Wolfe, R.F., and Holt, H.E., 1990,
124. Anderson, R.R., Hartung, J.B., Shoemaker, E.M., and Roddy, D.J.,
125. Attrep, M., Jr., Orth, C.J., Quintana, L.R., Shoemaker, C.S.,
126. Bowell, E., Muinonen, K., and Shoemaker, E.M., 1991, Discovery of
127. Holt, H.E., Bowell, E., Shoemaker, C.S., and Shoemaker, E.M., 1991,
128. Hut, P., Shoemaker, E.M., Alvarez, W., and Montanari, A., 1991,
129. Hut, P., Shoemaker, E.M., Alvarez, W., and Montanari, A., 1991,
130. Levison, H.F., Shoemaker, E.M., and Wolfe, R.F., 1991, Mapping the
131. Levison, H.F., Shoemaker, E.M., and Wolfe, R.F., 1991, Mapping the
132. Muinonen, Karri, Bowell, Edward, Shoemaker, E.M., and Wolfe, R.F.,
133. Plescia, J., Shoemaker, E.M., and Shoemaker, C.S., 1991, Gravity
134. Shoemaker, C.S., Shoemaker, E.M., Wolfe, R.F., 1991, Systematic
135. Shoemaker, E.M., 1991, Geological and astronomical evidence for comet
136. Shoemaker, E.M., Wolfe, R.F., and Shoemaker, C.S., 1991, Asteroid
137. Shoemaker, E.M., Wolfe, R.F., Shoemaker, C.S., Bowell, E., Muinonen,
138. Steiner, M., Morales, M., and Shoemaker, E.M., 1991, Relative ages of
139. Nishiizumi, K., Kohl, C.P., Arnold, J.R., Caffee, M.W., Finkel, R.C.,
140. Anderson, R.R., Hartung, J.B., Roddy, D.J., and Shoemaker, E.M.,
141. Shoemaker, E.M., 1992, Large-body impact is a geologic process
142. Shoemaker, E.M., and Izett, G.A., 1992, Stratigraphic evidence from
143. Shoemaker, E.M., and Izett, G.A., 1992, K/T boundary stratigraphy:
144. Shoemaker, E.M., and Steiner, M.B., 1992, Reversely magnetized
145. Anderson, R.R., Witzke, B.J., Hartung, J.B., Shoemaker, E.M., and
146. Anderson, R.R., Witzke, B.J., Shoemaker, E.M., Roddy, D.J., and
147. Bowell, Edward, Levison, Harold F., Shoemaker, Eugene M., and
148. Roddy, D.J., and Shoemaker, E.M., 1993, The Manson Impact Crater:
149. Shoemaker, E.M., Herkenhoff, K.E., and Gostin, V.A., 1993, Impact
150. Shoemaker, C.S., Holt, H.E., Shoemaker, E.M., Bowell, E., and Levy,
151. Shoemaker, E.M., and Nozette, Stewart, 1993, Clementine: An
152. Shoemaker, E.M., Roddy, D.J., and Anderson, R.R., 1993, Research
153. Shoemaker, E.M., and Shoemaker, C.S., 1993, The flux of periodic
154. Shoemaker, E.M., Shoemaker, C.S., and Levinson, H.F., 1993, Survey of
155. Shoemaker, E.M., Shoemaker, C.S., and Levy, D.H., 1993, Collision of
156. Steiner, M.B., and Shoemaker, E.M., 1993, The late Cretaceous Manson
157. Steiner, M.B., and Shoemaker, E.M., 1993, Two-polarity magnetization
158. Vorder Bruegge, R.W., Davies, M.E., Horan, D.M., Lucey, P.G., Pieters,
159. Vorder Bruegge, R.W., and Shoemaker, E.M., 1993, The Clementine
160. Anderson, R.R., Witzke, B.J., Roddy, D.J., and Shoemaker, E.M., 1994,
161. Izett, G.A., Masaitis, V.L., Shoemaker, E.M., Dalrymple, G.B., and
162. Pieters, C.M., Staid, M.I., Fischer, E.M., Shoemaker, G., and the
163. Robinson, M.S., and Shoemaker, E.M., 1994, Volcanic Materials of the
164. Roddy, D.J., Shoemaker, E.M., and Anderson, R.R., 1994, The Manson
165. Shoemaker, E.M., 1994, Clementine at Geographos (abs.), in Abstracts
166. Shoemaker, E.M., 1994, Late Impact History of the Solar System
167. Shoemaker, E.M., 1994, Update on the Impact Rates in the Jovian
168. Shoemaker, E.M., 1994, The Moon and Voyager: Highlights of Solar
169. Shoemaker, E.M., 1994, Ignorance of History is Bliss (abs.), in
170. Shoemaker, E.M., 1994, Clementine at the Moon (abs.), Bull. America
171. Shoemaker, E., and Cheng, A.F., 1994, Near Earth Asteroid Returned
172. Shoemaker, E.M., and Shoemaker, C.S., 1994, The Crash of
173. Shoemaker, E.M., Hassig, P.J., and Roddy, D.J., 1994, Impact Plume
174. Shoemaker, E.M., Robinson, M.S., and Eliason, E.M., 1994, Age
175. Steiner, M.B., and Shoemaker, E.M., 1994, The Late Cretaceous Manson
176. Steiner, M. and Shoemaker, E., 1994, Two-polarity magnetization of
177. Weaver, H.A., Noll, K.S., Storrs, A.D., Smith, T.E., A’Hearn, M.F.,
178. McEwen, A.S., and Shoemaker, E.M., 1995, Two classes of impact basins
179. Robinson, M.S., and Shoemaker, E.M., 1995, Clementine UVVIS high
180. Roddy, D.J., and Shoemaker, E.M., 1995, Meteor Crater (Barringer
181. Roddy, D.J., Shoemaker, E.M., and Anderson, R.R., 1995, Manson impact
182. Schmitt, H.H., Griffin, M.D., Kulcinski, G.L., and Shoemaker, E.M.,
183. Shoemaker, E.M., and Robinson, M.S., 1995, Clementine observations of
184. Shoemaker, E.M., Roddy, D.J., Moore, C.B., Pfeilsticker, R., Curley,
185. Kargel, J.S., Coffin, P., Kraft, M., Lewis, J.S., Moore, C., Roddy,
186. Kriens, B. J., Herkenhoff, K.E., and Shoemaker, E.M., 1996, Structure
187. Nozette, S., Lichtenberg, C.L., Spudis, P. Bonner, R., Ort, W.,
188. Robinson, M.S., Shoemaker, E.M., and Hawke, B.R., 1996, Spectral
189. Shoemaker, E.M., 1996, Exploration of near-earth asteroids (abs.), in
190. Shoemaker, E.M., 1996, Impact sites of comets and asteroids (abs.) in
191. Shoemaker, E.M., 1996, The Age of Europa’s Surface (abs.), in Europa
192. Shoemaker, E.M., Nishiizumi, K., and Kohl, C.P., 1996, The frequency
193. Shoemaker, E.M. and Shoemaker, C.S., 1996, The impact record of
194. Shoemaker, E.M. and Shoemaker, C.S., 1996, Small body collisions with
195. Shoemaker, E.M. and Shoemaker, C.S., 1996, Possible variations in the
196. Shoemaker, E.M. and Uhlherr, H.R., 1996, Stratigraphic relations of
197. Shoemaker, E.M., 1997, Long-term variations in the impact cratering
198. Shoemaker, E.M., 1997, How young is Europa’s surface? (abs.), in 1997
199. Shoemaker, E.M., and Shoemaker, C.S., 1997, Notes on the geology of
200. Shoemaker, E.M., and Shoemaker, C.S., 1997, Glikson, a probable
201. Shoemaker, E.M. and Shoemaker, C.S., 1997, Dispersion of stones by
202. Shoemaker, E.M., and Wynn, J.C., 1997, Geology of the Wabar meteorite
The impact of comets has profoundly influenced the story of life."
-- Gene Shoemaker
"Every time a giant comet strikes the Earth, the dice of evolution are thrown again." David Levy, Comets: Creators and Destroyers;Touchstone Books. 1998
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Gene Shoemaker Timeline
Some History of A Pale Blue Dot
"Tempus edax rurum." - "Time, the devourer of all things." Ovid
Origin to 545 million years ago
545 to 245 million years ago
245 to 65 million years ago
65 million years ago to present
Stand still you ever-moving spheres of heaven,
That time may cease, and midnight never come.
--Christopher Marlowe (1564 - 1593)
(This period makes up approximately 7/8ths of the Earth's history!)
The Solar System and Earth are born from a churning nebula of dust and gas and heavy elements derived from an earlier supernova in the galactic neighbourhood. When the sun ignited a violent shock hurled most of the stellar debris into deep space. Proplyds, containing organic molecules, condense even further to form the planetary system surrounding our star. The sun was cooler, radiating 25% less energy than today.
Ordovician Mass extinction - 440 - 450 million years ago was the second greatest mass extinction of marine life in the history of Earth, caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, and graptolites. Much of the reef-building fauna was also decimated. In total, more than one hundred families of marine invertebrates perished in this extinction.
The forests were composed of giant club mosses, tree ferns, and horsetails, some of which towered more than 30m (99ft) above the forest floor. The most abundant of the modern era coal supplies accumulated by the respiration of these forests.
The first reptiles evolve. Westlothiana, a tiny creature, contains many intermediate characters between primitive tetrapods and true
amniotes. The amniotic egg allowed Synapsida and Sauropsida the ancestors of birds and mammals, to breed away from water, opening up vast new environments for habitation. Insects were evolving such as the dragonflies with 71cm (28in) wingspans, and cockroaches over 10cm (4in) long. In the rivers and in the seas, the jawed, bony fish had largely replaced the jawless, heavily armored fish.
In the seas ammonoids have replaced the trilobites of the Permian. In the early Triassic they are characterized by subdued shell ornamentation but by the end of the period the shells become more decorative. Marine animals flourished in the warm, tropical oceans, in particular the ammonoids, brachiopods, and echinoderms.
Ferns and horsetail plants grew near water, tree-like cycadeoids and cycads were the tallest plants. Ginkoes and swamp cypress had evolved. Conifers evolved in upland dry areas. For most of this period the dominant land animal is a mammal-like reptile, aquatic, herbivorous therapsids, like the Dicynodonts. Their posture was sprawling and their size was from one to three meters in length.