Streaks on the Moon
Click for full image.
Cool image time! The photo to the right, reduced and enhanced to post here, is an oblique view taken by Lunar Reconnaissance Orbiter (LRO) of the rays that were created when four million years ago an object smashed into the Moon’s far side and produced the 13.75 mile-wide Giordano Bruno crater.
Rays are formed as material ejected from an impact event slams into the surface and churns up local material. Rays are bright because they expose fresh material from depth (both the incoming material and locally churned soil). What is fresh material? Over time the lunar surface is impacted by micrometeoroids and bombarded by radiation; both processes work to darken the surface. The dark “mature” layer at the surface is often only about 50 cm (20 inches) thick, so energetic impacts can easily bring up fresh material from the subsurface. Eventually, the bright rays darken and fade into the background as the surface matures.
In this image, you can see where the ejecta blocks from Giordano Bruno hit the surface, creating a secondary crater, which dug up local material and spread that bright material downstream (so to speak).
The image itself is 4.78 miles wide, at its center, and was snapped from an altitude of 66 miles.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for full image.
Cool image time! The photo to the right, reduced and enhanced to post here, is an oblique view taken by Lunar Reconnaissance Orbiter (LRO) of the rays that were created when four million years ago an object smashed into the Moon’s far side and produced the 13.75 mile-wide Giordano Bruno crater.
Rays are formed as material ejected from an impact event slams into the surface and churns up local material. Rays are bright because they expose fresh material from depth (both the incoming material and locally churned soil). What is fresh material? Over time the lunar surface is impacted by micrometeoroids and bombarded by radiation; both processes work to darken the surface. The dark “mature” layer at the surface is often only about 50 cm (20 inches) thick, so energetic impacts can easily bring up fresh material from the subsurface. Eventually, the bright rays darken and fade into the background as the surface matures.
In this image, you can see where the ejecta blocks from Giordano Bruno hit the surface, creating a secondary crater, which dug up local material and spread that bright material downstream (so to speak).
The image itself is 4.78 miles wide, at its center, and was snapped from an altitude of 66 miles.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
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