A comparison of images from the orbiter with lunar surveys has revealed a 22-meter-diameter crater formed between 2009 and 2012, providing new evidence that asteroids and comets continue to shape the lunar surface today.
A bright new lunar crater discovered in spacecraft images shows that asteroid collisions continue to change the surface of the moon today.
Ancient collisions shaped the surface of the moon
For most of the Moon's 4.5 billion year history, it has been severely impacted by collisions. The large basins that look like dark "seas" that make up the "Man in the Moon" were formed during an era of intense collisions that ended about 3.8 billion years ago.
Although the period of massive basin-forming collisions has long passed, the Moon is still impacted by asteroids and comets, which leave smaller and relatively younger craters.
Global albedo map of the Moon obtained from the Clementine mission. The dark areas are the lunar days, and the lighter areas are the highlands. Credit: US Geological Survey in Flagstaff
These events are very difficult to capture when they happen, so scientists usually identify them after the fact. Scientists working with the Lunar Reconnaissance Orbiter found such a crater by comparing detailed photographs of the same sites on the moon taken at different times. By examining images taken before December 2009 and images taken after December 2012, they were able to narrow down the time frame in which the impact occurred, even though no one actually observed it.
A new crater has been discovered.
The crater is 22 meters in diameter. It stands out not because of its size but because of its brightness. The impact threw material dozens of meters from the crater rim, creating distinct rays that radiate outward like sunbeams. There is a sharp contrast between this bright, new material and the darker surrounding rock, which highlights the crater like a new freckle on familiar skin.
Artist's impression of the lunar probe. Credit: NASA
These rays won't stay bright forever. Space weathering, the cumulative impact of solar wind particles, micrometeorite bombardment, and cosmic radiation gradually darken exposed lunar material. Over thousands to millions of years, this new crater will fade until it's indistinguishable from the countless ancient craters around it.
This darkening process is why older craters do not have prominent rays, while relatively new impacts like Tycho, which formed 108 million years ago, still have systems of bright rays visible from Earth.
The importance of new craters
The discovery of new craters serves several scientific purposes. It helps astronomers make more precise estimates of the current collision rate, which is essential for understanding the hazards facing future robotic and manned missions.
Additionally, observing the speed of darkening of the rays and erosion of crater formations allows scientists to calibrate their models to date the surfaces of other moons based on the density and appearance of craters.
Adapted from an article published inUniverseToday.
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