New Horizons Updates

New Horizons is getting close enough to detect geological features on the surface of Pluto.  Below is an image released on July 10th.

Credit: NASA

Craters are an indication of the age of the surface of a planet (or in this case, dwarf-planet).  The more craters there are, the older the surface.  The less craters there are, the younger the surface and it is an indication of active geological processes on that surface.

Lets take a look at a celestial body we are familiar with, the Moon.

Credit: NASA/Sean Smith

The bright, highly cratered areas are referred to as the highlands.  The surface age here ranges from 4 to 4.5 billion years old.  The darker, less cratered areas are referred to as mare regions.  These surfaces are about 3.5 billion years old.  Why are the mare regions younger than the highlands?  The mare regions were formed by large impact events that caused lava to flood these areas and eventually solidify into basaltic rocks.  This process wiped out the original cratered surface that existed before the impact events.

The Earth’s surface has very few craters due to a variety of geological processes.  This would include plate tectonics along with both wind and water erosion.  One crater that has been preserved, so far, is the Meteor Crater in Arizona.

Credit: USGS/D. Roddy

The dry climate (and lack of water erosion) has preserved this crater since the impact that created it 50,000 years ago.  Keep in mind, that is very young geologically speaking.  The Arizona Meteor Crater is only 0.0014% the age of the lunar mare regions.  One can visit the Meteor Crater and details on that are here.

The expectation is that Pluto will resemble the Neptune satellite Triton as both are about the same size.  Pluto is a Kuiper Belt object while Triton is a Kuiper Belt object that was captured by Neptune’s large gravity well.  Voyager 2 visited Triton in 1989 and this is what it saw:

The surface of Triton is lightly cratered and is estimated to be about 10 million years old.  Still pretty young, as that is about 0.3% the age of the lunar mare regions.  Voyager detected geyser like formations that vented nitrogen gas onto the surface.  This type of cryovolcanic activity is suspected to be the responsible party for Triton’s young surface.

How will Pluto compare?  We’ll know next week and the following months as images continue to download from New Horizons.  Keep in mind, the less craters there are, the more active the surface is.

*Image on top of post is artist conception of New Horizons flyby.  Credit:  NASA.

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