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Some objects in the solar system are in a “gray area,” and can be classified under more than one heading. Add the asteroid Pallas to that group. New close-up images of Pallas from the Hubble Space Telescope reveal that the second largest asteroid in the solar system appears to be a protoplanet, as well.
Britney E. Schmidt, a UCLA doctoral student, led a team of researchers to create a 3D model of the 600km-wide rock which lies within the main asteroid belt between the orbits of Jupiter and Mars.
With the Hubble images, Schmidt and her colleagues were able to take new measurements of Pallas’ size and shape. What they found showed that Pallas wasn’t just a big rock made of hydrated silicate and ice. An artist’s conception of an impact event on Pallas. This artwork was created using the three-dimensional shape model published by Britney Schmidt, et al. in Science. Credit: Image courtesy of B. E. Schmidt and S. C. Radcliffe
“It was incredibly exciting to have this new perspective on an object that is really interesting and hadn’t been observed by Hubble at high resolution,” Schmidt said of the first high-resolution images of Pallas, which is believed to have been intact since its formation, most likely within a few million years of the birth of our solar system.
“We were trying to understand not only the object, but how the solar system formed,” Schmidt said. “We think of these large asteroids not only as the building blocks of planets but as a chance to look at planet formation frozen in time.”
Visible in the Hubble images were areas of dark and light on Pallus’ surface, indicating that the water-rich body might have undergone an internal change in the same way planets do.
“That’s what makes it more like a planet — the color variation and the round shape are very important as far as understanding, is this a dynamic object or has it been exactly the same since it’s been formed?” Schmidt said. “We think it’s probably a dynamic object.”
For the first time, a large depression was also seen on Pallas. They were unable to determine if it was a crater, but the depression did suggest something else important: that it could have led to Pallas’ small family of asteroids orbiting in space.
“It’s interesting, because there are very few large, intact asteroids left,” Schmidt said. “There were probably many more. Most have been broken up completely. It’s an interesting chance to almost look into the object, at the layer underneath. It’s helping to unravel one of the big questions that we have about Pallas, why does it have this family?”
The massive body is unique, she said, partly because “its orbit is so much different from other asteroids. It’s highly inclined.”
“It was incredibly exciting to have this new perspective on an object that is really interesting and hadn’t been observed by Hubble at high resolution,” said Schmidt.
“When people think of asteroids, they think of ‘Star Wars’ or of tiny little rocks floating through space,” Schmidt said. “But some of these have been really physically dynamic. Around 5 million years after the formation of the solar system, Pallas was probably doing something kind of interesting.”
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For the first time, astronomers have confirmed that an asteroid contains frozen water on its surface. Analysis of asteroid 24 Themis shows evidence of water ice along with organic compounds widespread across the surface. The scientists say these new findings support the theory that asteroids brought both water and organic compounds to the early Earth, helping lay the foundation for life on the planet.
Humberto Campins of the University of Central Florida in Orlando and colleagues recorded spectra of 24 Themis over a seven-hour period, and were able to study 84 percent of the rotational period of the spinning rock, Rob Cowen reported in Science News. Using NASA’s Infrared Telescope Facility on Hawaii’s Mauna Kea, the spectra revealed the consistent presence of frozen water as different parts of the asteroid’s surface came into view.
Analyses of the sunlight reflected off the asteroid also show that organic compounds are widespread on the surface, he added, including polycyclic aromatic hydrocarbons, CH2 and CH3.
The new finding corroborates earlier observations of the same asteroid by astronomers Andrew S. Rivkin and Joshua Emery who also used the Infrared Telescope Facility. Over several years, Rivkin and Emery had found evidence of frozen water in single spots on 24 Themis but had not studied the asteroid as it made one entire rotation. Together, the two teams’ findings reveal that the asteroid’s entire surface is coated with frozen water, Campins says.
The 160-kilometer wide asteroid averages a distance from the sun of about 3.2 times that of Earth’s. At that range, frozen water on the surface would readily vaporize, Campins said. That means the ice must be continually replenished, possibly by a reservoir of frozen water within the rock.
One possibility is that ice lies buried several meters below the surface of 24 Themis, and when hit by space debris, the ice makes its way to the surface. If this is the case, it could confirm that some asteroids resemble comets, becoming active suddenly and venting material into space when pockets of ice vaporize, Campins said.
Another option is that an action similar to the recent findings of water on the Moon, where solar wind interacts with a rocky body without an atmosphere to create H2O and OH molecules. Without an atmosphere, the body is exposed to solar wind, which includes hydrogen ions. The hydrogen is able to interact with oxygen in surface of the asteroid to create water molecules.
Campins shared his findings at the annual meeting of the American Astronomical Society’s Division for Planetary Sciences.
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NASA scientists have recalculated the path of the large asteroid Apophis, significantly downgrading the odds of it hitting Earth. Using new information, the refined path indicates a 1 in 250,000 chance of impact in 2036, reduced from the 1 in 45,000 odds calculated earlier. The asteroid is expected to make a record-setting — but harmless — close approach to Earth on Friday, April 13, 2029, when it comes no closer than 18,300 miles above Earth’s surface.
The new information provided a more accurate glimpse of 2036 Apophis’ orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately 1 in 333,000. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about 2029 Apophis is acquired.
Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteriod ruled out any possibility of an impact in 2029.
The Apophis asteroid is approximately the size of two-and-a-half football fields.
“The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared,” said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. “The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed.”
The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA’s Jet Propulsion Laboratory. A majority of the data that enabled the updated orbit of Apophis came from observations made by Dave Tholen and collaborators at the University of Hawaii’s Institute for Astronomy in Manoa. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii’s 88-inch telescope, located near the summit of Mauna Kea.
Tholen made improved measurements of the asteroid’s position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory’s 90-inch Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley’s calculations.
“Apophis has been one of those celestial bodies that has captured the public’s interest since it was discovered in 2004,” said Chesley. “Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million.”
The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.
NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes. The Near Earth-Object Observations Program, commonly called “Spaceguard,” discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.
Discovery images of asteroid 2008 TC3, as it was seen on October 6, 2008, by the Catalina Sky Survey at Mount Lemmon in Arizona (Richard Kowalski).
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The first asteroid to have been spotted before hitting Earth, 2008 TC3, crashed in northern Sudan one year ago on October 6. Several astronomers have been trying to piece together a profile of this asteroid, pulling together information from meteorites found at the impact site and the images captured of the object in the hours before it crashed to Earth.
“We have a gigantic jigsaw puzzle on our hands, from which we try to create a picture of the asteroid and its origins,” said SETI Institute astronomer Peter Jenniskens, who worked at the crash site, “and now we have with a composite sketch of the culprit, cleverly using the eyewitness accounts of astronomers that saw the asteroid sneak up on us.” Their description? 2008 TC3 looked like a loaf of walnut-raisin bread.
“The asteroid now has a face,” said Jenniskens, chair of the special session at the fall meeting for the Division for Planetary Sciences of the American Astronomical Society. Last December, Jenniskens and Sudan astronomer Muawia Shaddad went to the crash site and recovered 300 fragments in the Nubian Desert. Like detectives, students from the University of Khartoum helped sweep the desert to look for remains of the asteroid. They found many different-looking meteorites close to, but a little south, of the calculated impact trajectory.
The team has also been able to recreate the shape of the asteroid from looking at images captured by Astronomers Marek Kozubal and Ron Dantowitz of the Clay Center Observatory in Brookline, Massachusetts, who tracked the asteroid with a telescope and captured the flicker of light during a two hour period just before impact.
An irregular shape and rapid tumbling caused asteroid 2008 TC3 to flicker when it reflected sunlight on approach to Earth.
Peter Scheirich and colleagues at Ondrejov Observatory and Charles University in the Czech Republic combined all the various observations to work out the shape and orientation of the asteroid.
Other forensic evidence based on analysis of the recovered meteorites at the Almahata Sitta site showed the asteroid was an unusual “polymict ureilite” type. Jason S. Herrin of NASA’s Johnson Space Center confirmed that the meteorites still carry traces of being heated to 1150-1300 degrees C, before rapidly cooling down at a rate of tens of degrees C per hour, during which carbon in the asteroid turned part of the olivine mineral iron into metallic iron. Hence, asteroid 2008 TC3 is the remains of a minor planet that endured massive collisions billions of years ago, melting some of the minerals, but not all, before a final collision shattered the planet into asteroids.
Mike Zolensky of NASA’s Johnson Space Center first pointed out that, as far as ureilites are concerned, his meteorite is unusually rich in pores, with pore walls coated by crystals of the mineral olivine. He now reports, from X-ray tomography work with Jon Friedrich of Fordham University in New York, that those pores appear to outline grains that have been incompletely welded together and that the pore linings appear to be vapor phase deposits. According to Zolensky, “Almahata Sitta may represent an agglomeration of coarse- to fine-grained, incompletely reduced pellets formed during impact, and subsequently welded together at high temperature.”
The carbon in the recovered meteorites is among the most cooked of all known meteorites. Carbon crystals of graphite and nanodiamonds have been detected. Still, it turns out that some of the organic matter in the original material survived the heating. Amy Morrow, Hassan Sabbah, and Richard Zare of Stanford University have found polycyclic aromatic hydrocarbons in high abundances. Amazingly, Michael Callahan and colleagues of NASA’s Goddard Space Flight Center now report that even some amino acids have survived.
Jenniskens and Shaddad plan to revisit the scene of the crash in the Nubian Desert. They reported their findings at the Division for Planetary Sciences of the American Astronomical Society meeting in Puerto Rico.
NASA’s Marshall Space Flight Center is testing a new robotic lunar lander test bed that will aid in the development of a new generation of multi-use landers for future robotic space exploration. Image Credit: NASA/MSFC/David Higginbotham
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The best way to study the new-found water on the Moon would be with in-situ instruments. Since humans won’t be making any lunar landings for at least a decade, the next best option is robotic spacecraft. NASA’s Marshall Space Flight Center is developing and testing a new robotic lander to explore not only the Moon, but also asteroids and Mars. This design is definitely next generation: it’s bigger than any lander yet and MSFC is currently testing the all-important final of reaching the destination: landing.
“Specifically, what we are doing at Marshall is identifying the terminal – or the final – phase of landing, and designing a robotic lander to meet those needs,” said Brian Mulac, a test engineer at Marshall, quoted in an article in the Huntsville Times. “That last part is the highest risk of setting down on the moon.”
Of course, parachutes can’t be used for landing on the Moon or asteroids, since neither destination has an atmosphere, so thrusters are key for landing.
Large, oval-shaped tanks on the craft are used to store fuel for thrusters. Thrusters guide the lander, controlling the vehicle’s altitude and speed for landing. An additional thruster on this test vehicle, above, offsets the effect of Earth’s gravity so that the other thrusters can operate as they would in a lunar environment.
Just in case the tests don’t go as planned, a huge net is place under the lander to catch the vehicle and avoid damaging it.
As the saying goes, it’s not the fall that’s dangerous, but the sudden stop.
[/caption] What killed the dinosaurs? That’s a question that has puzzled paleontologists since dinosaurs were first discovered. Maybe the global climate changed, maybe they were killed by disease, volcanoes, or the rise of mammals. But in the last few decades, a new theory has arisen; an asteroid strike millions of years ago drastically changed the Earth’s environment. It was this event that pushed the dinosaurs over the edge into extinction. What’s the evidence for this asteroid impact? A thin dark line found in layers of sediment around the world; evidence that something devastating happened to the planet 65 million years ago. This line is known as the K-T boundary.
What is the K-T boundary? K is actually the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period. So the K-T boundary is the point in between the Cretaceous and Tertiary periods. Geologists have dated this period to about 65.5 million years ago.
When physicist Luis Alvarez and geologist Walter Alvarez studied the K-T boundary around the world, they found that it had a much higher concentration of iridium than normal – between 30-130 times the amount of iridium you would expect. Iridium is rare on Earth because it sank down into the center of the planet as it formed, but iridium can still be found in large concentrations in asteroids. When they compared the concentrations of iridium in the K-T boundary, they found it matched the levels found in meteorites.
The researchers were even able to estimate what kind of asteroid must have impacted the Earth 65.5 million years ago to throw up such a consistent layer of debris around the entire planet. They estimated that the impactor must have been about 10 km in diameter, and release the energy equivalent of 100 trillion tons of TNT.
When that asteroid struck the Earth 65.5 million years ago, it destroyed a region thousands of kilometers across, but also threw up a dust cloud that obscured sunlight for years. That blocked photosynthesis in plants – the base of the food chain – and eventually starved out the dinosaurs.
Researchers now think that the asteroid strike that created the K-T boundary was probably the Chicxulub Crater. This is a massive impact crater buried under Chicxulub on the coast of Yucatan, Mexico. The crater measures 180 kilometers across, and occurred about 65 million years ago.
Geologists aren’t completely in agreement about the connection between the Chicxulub impact and the extinction of the dinosaurs. Some believe that other catastrophic events might have helped push the dinosaurs over the edge, such as massive volcanism, or a series of impact events.
Planetoid is another term for asteroids, which are also called minor planets. Planetoids are small celestial bodies that orbit the Sun. Planets are simply defined as asteroids, but the term asteroid is not well defined either. In 2006, The International Astronomical Union (IAU) defined it as a “small Solar System body” (SSSB), which does not really tell us anything either. Webster’s Dictionary defines an asteroid as, “any of the thousands of small planets ranging from 1,000 km (621 mi) to less than one km (0.62 mi) in diameter, with orbits usually between those of Mars and Jupiter; minor planet; planetoid.”
Asteroids – planetoids – were first discovered in 1801, and many more have been discovered since then. Up until 1977, almost all the asteroids discovered were near Jupiter. However, then astronomers began to discover planetoids even farther out and started calling them centaurs and trans-Neptunian objects (TNOs). When a region of space in the outer Solar System filled with celestial bodies was discovered, it was called the Kuiper Belt and the objects in it were called Kuiper Belt Objects (KBOs). The large number of synonyms for planetoids is one reason why keeping these terms straight is so difficult.
Some of the largest planetoids are spherical and look like tiny versions of planets. The smaller ones are irregular in shape though. The objects range in size from around ten meters to hundreds of kilometers in diameter. Objects smaller than ten meters are called meteoroids. Unfortunately, astronomers do not know that much about the materials that make up planetoids. They are believed to be composed of various materials including ice, rock, and different metals.
Most planetoids are in a region called the asteroid belt, which is situated between Mars and Jupiter. There are millions of planetoids in this region. Despite the millions of objects, all of them combined are believed to have a mass of only about 4% of the Moon’s mass. After being discovered, the planetoids are given a temporary designation. If they are officially recognized, they are given a number and maybe a name. The first few planetoids were given symbols just like the planets. All except one of the first fifteen asteroids were given extremely complex symbols. For example, one symbol was a star with a plant growing out of it. However, that soon ended when astronomers realized that there were many more planetoids. Planetoids, and other celestial bodies, are a subject of study by astronomers who hope to learn more about how the universe was formed from these ancient rocks.
Trojan asteroids sharing the orbits of Jupiter and Neptune. Image credit: Scott Sheppard.
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A planetesimal is an object formed from dust, rock, and other materials. The word has its roots in the concept infinitesimal, which indicates an object too small to see or measure. Planetesimals can be anywhere in size from several meters to hundreds of kilometers. The term refers to small celestial bodies formed during the creation of planets. One way to think of them is as small planets, but they are much more than that.
The planetesimal theory was suggested by the Russian astronomer Viktor Safronov. The planetesimal theory is a theory on how planets form. According to the planetesimal hypothesis, when a planetary system is forming, there is a protoplanetary disk with materials from the nebulae from which the system came. This material is gradually pulled together by gravity to form small chunks. These chunks get larger and larger until they form planetesimals. Many of the objects break apart when they collide, but some continue to grow. Some of these planetesimals go on to become planets and moons. Since the gas giants are balls of gas with liquid cores, it may seem impossible that an asteroid-like object formed them. The planetesimals formed the core of these gaseous planets, which turned molten when it enough heat was created.
Other planetesimals turn into comets, Kuiper Belt Objects (KBOs), and trojan asteroids. There is some debate as to whether KBOs and asteroids can be called planetesimals. This is one reason why nomenclature of celestial objects is so difficult. The planetesimal theory is not universally accepted though. Like many theories, there are some observations that cannot be explained, but the planetesimal theory is still very popular.
Many people think that around 3.8 billion years ago, many of the planetesimals were thrown into far away regions, such as the Oort cloud or the Kuiper Belt. Other objects collided with other objects after being affected by gas giants. Phobos and Deimos are believed to be planetesimals that were captured by Mars’ gravity and became satellites. Many of Jupiter’s moons are believed to be planetesimals as well.
Planetesimals are very valuable to scientists because they can provide information about the creation of our Solar System. The exterior of planetesimals have been bombarded with solar radiation, which can change their chemistry, for billions of years. Inside though, there is material that has been untouched since the object was first formed. Using this material, astronomers hope to learn about the condition of the nebulae from which our Solar System was formed.
Ceres, the recently promoted dwarf planet in the asteroid belt is still too small to be easily seen by Hubble credit: NASA/ESA/STScI
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Minor planet is a term used to refer to a celestial object – that is not a planet or comet – which orbits the Sun. Found in 1801, Ceres, also known as a dwarf planet, was the first minor planet discovered. The term minor planet has been in use since the 1800’s. Planetoids, asteroids, and minor planets have all been used interchangeably, but the situation became even more confusing when the International Astronomical Union (IAU) committee reclassified minor planets and comets into the new categories of dwarf planets and small solar system bodies. At the same time, the IAU created a new definition of what a planet is, and Pluto was reclassified as a dwarf planet. Hydrostatic equilibrium – the ability to maintain a roughly spherical shape – is what separates dwarf planets from the more irregularly shaped small solar system bodies. The names become even more confusing because the IAU still recognizes the use of the term minor planets.
Minor planets are extremely common with over 400,000 registered and thousands more found each month. Approximately 15,000 minor planets have been given official names while the rest are numbered. When asteroids were first discovered, they were named after characters from Greek and Roman mythology like Ceres was. At first, astronomers thought that the asteroids, especially Ceres and Pallas were actually planets. Astronomers also created symbols for the first asteroids found. There were symbols created for 14 asteroids and some of them were very complex like Victoria’s symbol, which looks like a plant with three leaves growing out of an off center starburst. Soon, astronomers ran out of mythological names and started christening asteroids after television characters, famous people, and relatives of discoverers. Most names were feminine, attesting to an unnamed tradition. As the numbers ran into the thousands, scientists started using their pets as inspiration. After an asteroid was named 2309 Mr. Spock, pet’s names were banned. That did not stop the oddness though because names such as 9007 James Bond and 6402 Chesirecat have been suggested and actually accepted.
There are a number of different categories that minor planets fall into including asteroids, Trans-Neptunian objects, and centaurs. There are various types of asteroids, although most of them can be found in the asteroid belt, which is the region of space between Mars and Jupiter. Trans-Neptunian objects are celestial bodies found orbiting beyond Neptune, and centaurs are celestial bodies with unstable orbits located between Jupiter and Neptune. The categories also overlap, making classifying things a nightmare. For example, Ceres is a dwarf planet and minor planet, additionally it can also be classified as an asteroid.
Ever since our recent encounter with asteroid 2008 TC3 — the first asteroid that was correctly predicted to hit our planet — I’ve had impact craters on the brain. Earth has about 175 known impact craters, but surely our planet has endured more bashing than that in its history. All the other terrestrial planets and moons in our solar system are covered by impact craters. Just look at our Moon through a telescope or binoculars, or check out the recent images of Mercury sent back by the MESSENGER spacecraft, or pictures of Mars from the armada of spacecraft orbiting the Red Planet, and you’ll see that impact craters are the most common landforms in our solar system.
But since two-thirds of Earth is covered by water, any asteroid impacts occurring in the oceans are difficult to find. And even though Earth’s atmosphere protects us from smaller asteroids, just like in the case of 2008 TC3, which broke up high in the atmosphere, weathering, erosion and the tectonic cycling of Earth’s crust have erased much of the evidence of Earth’s early bombardment by asteroids and comets. Most of Earth’s impact craters have been discovered since the dawn of the space age, from satellite imaging. In fact, a geologist recently discovered an impact crater using Google Earth!
Here’s my list of Earth’s Ten Most Impressive Impact Craters, starting with #1. the largest and oldest known impact crater, Vredefort Crater, shown above, located in South Africa. It is approximately 250 kilometers in diameter and is thought to to be about two billion years old. The Vredefort Dome can be seen in this satellite image as a roughly circular pattern. What an impact that must have been!
Manicouagan Reservoir. Credit: NASA 2. Manicouagan Crater: fifth largest known impact crater. This crater is located in Quebec, Canada. It was created about 212 million years ago. Now, it is an ice-covered lake about 70 km across. This image, taken by space shuttle astronauts, shows an outer ring of rock. Close up, the rock reveals clear signs of having been melted and altered by a violent collision. The original rim of the crater, though now eroded away, is thought to have had a diameter of about 100 km.
Chicxulub Crater. 3. Chicxulub Crater, third largest and possible dinosaur killer. The third largest impact crater lies mostly underwater and buried underneath the Yucatán Peninsula in Mexico. At 170km (105 miles) in diameter, the impact is believed to have occurred roughly 65 million years ago when a comet or asteroid the size of a small city crashed, unleashing the equivalent to 100 teratons of TNT. Likely, it caused destructive tsunamis, earthquakes and volcanic eruptions around the world, and is widely believed to have led to the extinction of dinosaurs, because the impact probably created a global firestorm and/or a widespread greenhouse effect that caused long-term environmental changes.
Aorounga Crater. Credit: NASA 4. Aorounga Crater: possible triple crater. The main Aorounga Crater in Chad, Africa, visible in this radar image from space, shows a concentric ring structure that is about 17 kilometers wide. But, this crater might have been formed as the result of a multiple impact event. A second crater, similar in size to the main crater, appears as a circular trough in the center of the image. And a third structure, also about the same size, is seen as a dark, partial circular trough on the right side of the image. The proposed crater “chain” could have formed when a 1 km to 2 km (0.5 mile to 1 mile) diameter object broke apart before impact. Ouch! Clearwater craters. Credit: NASA 5. Clearwater Craters: two for the price of one. Twin, lake-filled impact craters in Quebec, Canada were probably formed simultaneously, about 290 million years ago, by two separate but probably related meteorite impacts. The larger crater, Clearwater Lake West has a diameter of 32 km, and Clearwater Lake East is 22 km wide.
Barringer Crater. 6. Barringer Crater: well preserved. While this crater isn’t all that big, what’s most impressive about Barringer Crater in Arizona (USA) is how well preserved it is. Measuring 1.2 km across and 175 m deep, Barringer Crater was formed about 50,000 years ago by the impact of an iron meteorite, probably about 50 m across and weighing several hundred thousand tons. Most of the meteorite was vaporized or melted, leaving only numerous, mostly small fragments with in the crater and scattered up to 7 km from the impact site. Only about 30 tons, including a 693-kg sample, are known to have been recovered. Wolfe Creek Crater 7. Wolfe Creek Crater, well preserved, too. Another relatively well-preserved meteorite crater is found in the desert plains of north-central Australia. Wolfe Creek crater is thought to be about 300,000 years old and is 880 meters across and and about 60 meters deep. It’s partially buried under the wind-blown sand of the region, and although the unusual landform was well-known to the locals, scientists didn’t find the crater until 1947. Deep Bay Crater. Credit: NASA 8. Deep Bay Crater: deep and cold. Deep Bay crater is located in Saskatchewan, Canada. The bay is a strikingly circular 13 km wide impact crater and is also very deep (220 m). It is part of an otherwise irregular and shallow lake. The age of the crater is estimated to be 99 million years old.
Kara-Kul Crater. Credit: NASA 9. Kara-Kul Crater: high altitude crater. This crater was formed about 10 million years ago, and is located in Tajikistan, near the Afghan border. In total, the crater is about 45 km in diameter and is partially filled with a 25 km-wide lake. This might be the “highest” impact crater, almost 6,000 m above sea-level in the Pamir Mountain Range. It was found only recently from satellite images.
Bosumtwi Crater. 10. Bosumtwi Crater: built of bedrock. The last crater on our tour of impressive impact craters is this located in Ghana, Africa. It is about 10.5 km in diameter and about 1.3 million years old. The crater is filled almost entirely by water, creating Lake Bosumtwi. The lakebed is made of crystalline bedrocks.
