Uploaded August 2010 | Updated September 2026, 1 week ago
facebook.com/ScienceReason ... Moon Reveals New Secrets to LRO Spacecraft: Newly discovered cliffs in the lunar crust indicate the moon shrank globally in the geologically recent past and might still be shrinking today, according to a team analyzing new images from NASA's Lunar Reconnaissance Orbiter, or LRO spacecraft. The results provide important clues to the moon's recent geologic and tectonic evolution.
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NASA's LRO Reveals Incredible Shrinking Moon (08.19.2010)
Newly discovered cliffs in the lunar crust indicate the moon shrank globally in the geologically recent past and might still be shrinking today, according to a team analyzing new images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft. The results provide important clues to the moon's recent geologic and tectonic evolution.
The moon formed in a chaotic environment of intense bombardment by asteroids and meteors. These collisions, along with the decay of radioactive elements, made the moon hot. The moon cooled off as it aged, and scientists have long thought the moon shrank over time as it cooled, especially in its early history. The new research reveals relatively recent tectonic activity connected to the long-lived cooling and associated contraction of the lunar interior.
"We estimate these cliffs, called lobate scarps, formed less than a billion years ago, and they could be as young as a hundred million years," said Dr. Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum. While ancient in human terms, it is less than 25 percent of the moon's current age of more than four billion years. "Based on the size of the scarps, we estimate the distance between the moon's center and its surface shrank by about 300 feet," said Watters, lead author of a paper on this research appearing in Science August 20.
"These exciting results highlight the importance of global observations for understanding global processes," said Dr. John Keller, Deputy Project Scientist for LRO at NASA's Goddard Space Flight Center. "As the LRO mission continues in to a new phase, with emphasis on science measurements, our ability to create inventories of lunar geologic features will be a powerful tool for understanding the history of the moon and the solar system."
The scarps are relatively small; the largest is about 300 feet high and extends for several miles or so, but typical lengths are shorter and heights are more in the tens of yards (meters) range. The team believes they are among the freshest features on the moon, in part because they cut across small craters. Since the moon is constantly bombarded by meteors, features like small craters (those less than about 1,200 feet across) are likely to be young because they are quickly destroyed by other impacts and don't last long. So, if a small crater has been disrupted by a scarp, the scarp formed after the crater and is even younger. Even more compelling evidence is that large craters, which are likely to be old, don't appear on top any of the scarps, and the scarps look crisp and relatively undegraded.
Lobate scarps on the moon were discovered during the Apollo missions with analysis of pictures from the high-resolution Panoramic Camera installed on Apollo 15, 16, and 17. However, these missions orbited over regions near the lunar equator, and were only able to photograph some 20 percent of the lunar surface, so researchers couldn't be sure the scarps were not just the result of local activity around the equator. The team found 14 previously undetected scarps in the LRO images, seven of which are at high latitudes (more than 60 degrees). This confirms that the scarps are a global phenomenon, making a shrinking moon the most likely explanation for their wide distribution, according to the team.
As the moon contracted, the mantle and surface crust were forced to respond, forming thrust faults where a section of the crust cracks and juts out over another. Many of the resulting cliffs, or scarps, have a semi-circular or lobe-shaped appearance, giving rise to the term "lobate scarps". Scientists aren't sure why they look this way; perhaps it's the way the lunar soil (regolith) expresses thrust faults, according to Watters.
• nasa.gov/mission_pages/LRO/news/shrinking-moon.html
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facebook.com/ScienceReason ... Moon Reveals New Secrets to LRO Spacecraft: Newly discovered cliffs in the lunar crust indicate the moon shrank globally in the geologically recent past and might still be shrinking today, according to a team analyzing new images from NASA's Lunar Reconnaissance Orbiter, or LRO spacecraft. The results provide important clues to the moon's recent geologic and tectonic evolution.
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NASA's LRO Reveals Incredible Shrinking Moon (08.19.2010)
Newly discovered cliffs in the lunar crust indicate the moon shrank globally in the geologically recent past and might still be shrinking today, according to a team analyzing new images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft. The results provide important clues to the moon's recent geologic and tectonic evolution.
The moon formed in a chaotic environment of intense bombardment by asteroids and meteors. These collisions, along with the decay of radioactive elements, made the moon hot. The moon cooled off as it aged, and scientists have long thought the moon shrank over time as it cooled, especially in its early history. The new research reveals relatively recent tectonic activity connected to the long-lived cooling and associated contraction of the lunar interior.
"We estimate these cliffs, called lobate scarps, formed less than a billion years ago, and they could be as young as a hundred million years," said Dr. Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum. While ancient in human terms, it is less than 25 percent of the moon's current age of more than four billion years. "Based on the size of the scarps, we estimate the distance between the moon's center and its surface shrank by about 300 feet," said Watters, lead author of a paper on this research appearing in Science August 20.
"These exciting results highlight the importance of global observations for understanding global processes," said Dr. John Keller, Deputy Project Scientist for LRO at NASA's Goddard Space Flight Center. "As the LRO mission continues in to a new phase, with emphasis on science measurements, our ability to create inventories of lunar geologic features will be a powerful tool for understanding the history of the moon and the solar system."
The scarps are relatively small; the largest is about 300 feet high and extends for several miles or so, but typical lengths are shorter and heights are more in the tens of yards (meters) range. The team believes they are among the freshest features on the moon, in part because they cut across small craters. Since the moon is constantly bombarded by meteors, features like small craters (those less than about 1,200 feet across) are likely to be young because they are quickly destroyed by other impacts and don't last long. So, if a small crater has been disrupted by a scarp, the scarp formed after the crater and is even younger. Even more compelling evidence is that large craters, which are likely to be old, don't appear on top any of the scarps, and the scarps look crisp and relatively undegraded.
Lobate scarps on the moon were discovered during the Apollo missions with analysis of pictures from the high-resolution Panoramic Camera installed on Apollo 15, 16, and 17. However, these missions orbited over regions near the lunar equator, and were only able to photograph some 20 percent of the lunar surface, so researchers couldn't be sure the scarps were not just the result of local activity around the equator. The team found 14 previously undetected scarps in the LRO images, seven of which are at high latitudes (more than 60 degrees). This confirms that the scarps are a global phenomenon, making a shrinking moon the most likely explanation for their wide distribution, according to the team.
As the moon contracted, the mantle and surface crust were forced to respond, forming thrust faults where a section of the crust cracks and juts out over another. Many of the resulting cliffs, or scarps, have a semi-circular or lobe-shaped appearance, giving rise to the term "lobate scarps". Scientists aren't sure why they look this way; perhaps it's the way the lunar soil (regolith) expresses thrust faults, according to Watters.
• nasa.gov/mission_pages/LRO/news/shrinking-moon.html
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![NASA Astronomy Pictures Of The Day [Week 5/2010]](https://i.ytimg.com/vi/dltImo5gm38/mqdefault.jpg "NASA Astronomy Pictures Of The Day [Week 5/2010]
http://facebook.com/ScienceReason ... NASA Astronomy Pictures Of The Day [Week 5/2010]
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► Stardust in Perseus
This cosmic expanse of dust, gas, and stars covers close to three degrees on the sky in the heroic constellation Perseus. Right of center in the gorgeous skyscape is the dusty blue reflection nebula NGC 1333, about 1,000 light-years away. At that estimated distance, the field of view is about 50 light-years across. Next to NGC 1333 is the reddish glow of shocked hydrogen gas created by energetic jets and winds from stars in the process of formation.
• http://antwrp.gsfc.nasa.gov/apod/ap100204.html
► Shepherd Moon Prometheus from Cassini
Another moon of Saturn has been imaged in detail by the Cassini spacecraft. Visible in an unprocessed image from 36,000 kilometers away, Prometheus 100-km long surface was revealed to have an interesting system of bulges, ridges, and craters. Cassinis next major targeted flyby is of the moon Rhea.
• http://antwrp.gsfc.nasa.gov/apod/ap100201.html
► Hong Kong Sky
This remarkable scene combines multiple exposures recorded from a waterside perspective in Hong Kong, China. It follows a young crescent Moon, with brilliant planet Jupiter to its left, as they set together in the western sky. Their two luminous trails are faintly paralleled by trails of background stars.
• http://antwrp.gsfc.nasa.gov/apod/ap100206.html
► The Einstein Cross Gravitational Lens
Most galaxies have a single nucleus does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The central cloverleaf is rather light emitted from a background quasar. The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images. The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident. The general effect is known as gravitational lensing, and this specific case is known as the Einstein Cross.
• http://antwrp.gsfc.nasa.gov/apod/astropix.html
► Mars and a Colorful Lunar Fog Bow
Even from the top of a volcanic crater, this vista was unusual. For one reason, Mars (on the far upper left) was dazzlingly bright when this picture was taken, as it was nearing its brightest time of the entire year.
• http://antwrp.gsfc.nasa.gov/apod/ap100202.html
► P/2010 A2: Unusual Asteroid Tail Implies Powerful Collision
First discovered on ground based LINEAR images, the object appeared unusual enough to investigate further with the Hubble Space Telescope. What Hubble saw indicates that P/2010 A2 is unlike any object ever seen before. At first glance, the object appears to have the tail of a comet. Close inspection, however, shows a 140-meter nucleus offset from the tail center, very unusual structure near the nucleus, and no discernable gas in the tail. Knowing that the object orbits in the asteroid belt between Mars and Jupiter, a preliminary hypothesis that appears to explain all of the known clues is that P/2010 A2 is the debris left over from a recent collision between two small asteroids. If true, the collision likely occurred at over 15,000 kilometers per hour five times the speed of a rifle bullet and liberated energy in excess of a nuclear bomb.
• http://antwrp.gsfc.nasa.gov/apod/ap100203.html
► Dust Storm on Mars
Its spring for the northern hemisphere of Mars and spring on Mars usually means dust storms. So the dramatic brown swath of dust (top) marking the otherwise white north polar cap in this picture of the Red Planet is not really surprising.
• http://antwrp.gsfc.nasa.gov/apod/ap100205.html
► The Colors of IC 1795
This colorful cosmic portrait features glowing gas and obscuring dust clouds in IC 1795, a star forming region in the northern constellation Cassiopeia. The nebulas colors were created by adopting the Hubble false-color palette for mapping narrow emission from oxygen, hydrogen, and sulfur atoms to blue, green and red colors, and further blending the data with images of the region recorded through broadband filters.
• http://apod.nasa.gov/apod/ap091210.html
► The International Space Station Over the Horizon
The STS-129 crew of the Space Shuttle Atlantis undocked from the International Space Station (ISS) and returned to Earth. As the shuttle departed the space station, they took the above image. The ISS continues to be home for five astronauts of Expedition 21.
• http://apod.nasa.gov/apod/ap091207.html
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