Mercury A to Z: Kuiper Crater

Hello, friends, and welcome back to the A to Z Challenge.  For this year’s challenge, my theme is the planet Mercury, and in today’s post K is for:

KUIPER CRATER

Mercury is a big, grey rock covered in craters.  In fact, Mercury is the most heavily cratered object in the whole Solar System.  So what’s so special about Kuiper Crater?  Why am I devoting an entire blog post to this one crater in particular?  Well, because Kuiper Crater is a surprisingly young and bright-looking crater among all the darker, older-looking craters of Mercury.

Kuiper Crater was officially discovered in 1974 by NASA’s Mariner 10 space probe.  Earth-based astronomers had seen it before (it is, as I said, very bright-looking), but they didn’t realize what it was.  Giovanni Schiaparelli, for example, apparently thought it was a cloud.  The crater was named after famed planetary scientist Gerard Kuiper, who was highly involved in the Mariner 10 mission but who, unfortunately, died only a few months before Mariner 10 reached Mercury (this was, by the way, before the I.A.U. established the rule that craters on Mercury should be named after artists, writers, and musicians).

Now you may be wondering how scientists can look at a crater and tell how old it is.  Unlike with people, lines and wrinkles are a clear sign of youth for a crater.  Fresh, recently formed craters have tall crater walls, sharply defined crater rims.  They have deep crater basins, and ejecta scattering away from a crater after impact leave obvious trails that radiate away from the crater across the planetary surface.  In the case of Mercury, newer craters also tend to be brighter in color.

Time wears all these signs of youth away.  Crater walls slowly crumble.  Crater basins get filled in with debris.  Those lines radiating away from newer craters gradually start to disappear.  And for craters on Mercury, solar and cosmic radiation causes the bright color to slowly fade away.

Looking at Kuiper Crater, it is very line-y, very wrinkly.  It’s also very bright, as I said before.  Kuiper Crater is, in fact, the single brightest spot on all of Mercury.  There does seem to be some scientific debate over Kuiper Crater’s exact age, but everyone seems to agree that it must be very young, that it formed very recently—within the last few hundred million years, perhaps.  That’s not a long time when compared to the age of the Solar System.

Much like Earth, Mercury’s geologic history is divided up into different eras.  Kuiper Crater is young enough and prominent enough that it lends its name to the current era of Mercury’s history: the Kuiperian Period.

WANT TO LEARN MORE?

This was not an easy topic to research.  I got most of my information for today’s post from this paper, titled “Revised Constraints on Absolute Age Limits for Mercury’s Kuiperian and Mansurian Stratigraphic Systems.”