The Moon's surface is better mapped than the bottom of our Earth's oceans. Although that may seem surprising, it makes sense. The Moon has no atmosphere, meaning that light dispersion doesn't blur or impede our view of it's surface. Even viewing the Moon through our own atmosphere at night can yield high resolution images.
In fact, you can use a x10 magnification binoculars and a smart phone (resting the two with a very steady hand!) and take a surprisingly good photo. With enough stacked images and some image processing a high resolution photo of the Moon can be captured with relative easy... our side of the Moon, that is.
So (!), despite the Moon's surface being well accounted for, the mechanism of formation of streak-like 'rays' emanating from craters was not fully understood. UNTIL NOW. This research article must surely give hope to any budding scientist who thought 'table-top' science was only a thing of the past. In the paper scientists drop marbles on to a bed of flour, mimicking the behaviour of an asteroid impacting the Moon. Awesome.
What they observed was that marbles falling on flour that had been flattened shows a uniform circular spread of 'dust' forming around the impact sight. HOWEVER, when the marble impacts an uneven bed of flour (e.g. a bumpy grid of hexagons), rays or streaks emanate away from the impact sight. They explain that a bumpy surface concentrates shock waves along specific paths that breaks the normal symmetry of impact on a flat surface. This channels the ejected material along specific paths.
What is fascinating is that they found that the relative size of the marble to the spacing of the bumps in the flour actually determines the number of rays that emanate from an impact site. This is very useful! It means that astronomers can look at the craters on the moon, count the impact rays and then estimate the topography of the moon and/or the size of the asteroid that must have hit it. Given that the Moon has hundreds of thousands of craters, with some big-data analysis, scientists will be able to find out the size distribution of asteroid impacts for the past (however many) millions of years!
For some perspective... Check out this video that shows how some research initiatives constantly monitor the Moon for new impact sites. This can number hundreds of new craters every year.
In fact, you can use a x10 magnification binoculars and a smart phone (resting the two with a very steady hand!) and take a surprisingly good photo. With enough stacked images and some image processing a high resolution photo of the Moon can be captured with relative easy... our side of the Moon, that is.
So (!), despite the Moon's surface being well accounted for, the mechanism of formation of streak-like 'rays' emanating from craters was not fully understood. UNTIL NOW. This research article must surely give hope to any budding scientist who thought 'table-top' science was only a thing of the past. In the paper scientists drop marbles on to a bed of flour, mimicking the behaviour of an asteroid impacting the Moon. Awesome.
What they observed was that marbles falling on flour that had been flattened shows a uniform circular spread of 'dust' forming around the impact sight. HOWEVER, when the marble impacts an uneven bed of flour (e.g. a bumpy grid of hexagons), rays or streaks emanate away from the impact sight. They explain that a bumpy surface concentrates shock waves along specific paths that breaks the normal symmetry of impact on a flat surface. This channels the ejected material along specific paths.
What is fascinating is that they found that the relative size of the marble to the spacing of the bumps in the flour actually determines the number of rays that emanate from an impact site. This is very useful! It means that astronomers can look at the craters on the moon, count the impact rays and then estimate the topography of the moon and/or the size of the asteroid that must have hit it. Given that the Moon has hundreds of thousands of craters, with some big-data analysis, scientists will be able to find out the size distribution of asteroid impacts for the past (however many) millions of years!
For some perspective... Check out this video that shows how some research initiatives constantly monitor the Moon for new impact sites. This can number hundreds of new craters every year.
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