Mercury in closeup - Kuiper and more

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

This stunning view is Kuiper* crater, the central feature in the image from last Tuesday. The crater itself is 62km in diameter (39 miles) but the ejecta from the impact fan out over a much greater distance.

The Messenger website observes:

Bright ejecta rays such as these are produced as impacts excavate and eject relatively unweathered subsurface material. The ejecta rays of Kuiper and other large craters are observed to extend for hundreds of kilometers across the cratered terrain of Mercury

But the real guy responsible for the rays is here:

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

This is the (as yet unnamed?) crater at about 1 o'clock in Tuesday's image. Measuring about 110km across (68 miles) the central impact has spread ejecta over half the planet.

Again from the website:

A striking characteristic of this newly imaged area is the large pattern of rays that extend from the northern region of Mercury to regions south of Kuiper. This extensive ray system appears to emanate from a relatively young crater newly imaged by MESSENGER, providing a view of the planet distinctly unique from that obtained during MESSENGER’s first flyby. This young, extensively rayed crater, along with the prominent rayed crater to the southeast of Kuiper, near the limb of the planet, were both seen in Earth-based radar images of Mercury but not previously imaged by spacecraft.

Yeah, but what do they mean by young?
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*Named in honour of Gerard Kuiper, he of Kuiper Belt fame. Though is seems he had bugger all to do wih it really.