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  Night Sky
 

Enjoy the starry night skies
Be a considerate neighbor. Reduce nighttime glare.
Shield your outside lights downward.
Let the stars light up the night.

August 2016 night sky

—Charlie Christmann

Pluto plus one year

It is hard to believe that it was just a year ago, on July 14, 2015, that New Horizons swept past Pluto. It has taken almost that long to transmit the data the spacecraft gathered during that brief encounter. So, what have we learned, and what is still puzzling as planetary scientists pour over the data?

Before New Horizons, Pluto was expected to be a dead, cold, inert ball of ices. Scientists expected to learn much about the origins of our solar system from such a pristine object by looking at its ices and their compositions. Ironically, it may be dwarf minor planets that yield the most information about how we got here.

As usual, the experts were confounded even before the closest approach. Images started showing geologic features on the surface as the spacecraft approached that were never expected. S. Alan Stern, the mission’s principal investigator, said of the experience, “It’s much more complex than people, ourselves as experts included, expected. It rivals Mars.”

“You’d expect to see a boring cratered ball,” said William M. Grundy of Lowell Observatory in Arizona, who leads the team analyzing the composition of Pluto’s surface.

The first shock was seeing a smooth heart-shaped region, now called Tombaugh Regio after New Mexican Clyde Tombaugh, the discoverer of Pluto. One side of the region is covered in nitrogen ice (which freezes at -346°F), the other with methane ice (which freezes at -295.6°F). There were few craters in the region indicating ongoing processes to reshape the area and cover up the impacts.

New evidence also finds that Pluto probably had, and likely still has, a subsurface water ocean. The cracks seen across the landscape are indicative of the planet slowly freezing. Since water expands as it freezes, the surface of Pluto has also expanded and cracked. Other indications are mountains of water ice, as high as 11,000 feet high. While much of the surface is nitrogen and methane ices, water ice acts like bed rock here on Earth. At Pluto’s frigid temperatures, somewhere between -400°F and -360°F, ice is very hard.

There are also blocks of water ice jamming together to form mountains. These may be similar to icebergs on Earth, except the icebergs are floating on a denser sea of nitrogen ice.

A mountain, named Wright Mons, is somewhat confounding. It rises two miles above the terrain, spans ninety miles across and has a hole at the center. Wright Mons is thought to be a volcano spewing not hot lava, but nitrogen. If nitrogen is transported deep enough underground, the warmer water ice would melt the nitrogen and create the volcano as the nitrogen erupts to the surface.

Pluto’s largest moon, Charon, is half the size of Pluto. Yet the moon is much less dense, indicating it is mostly water ice and much less of the other ices. As Charon cooled and froze, it too expanded and left a gaping six hundred mile-long crack on its surface.

The rest of Pluto’s tiny moons, four small ones, spin wildly as they orbit, likely created in a collision between an infant Pluto and similar sized object. This collision created the dwarf planet and all of its moons. Finally, Pluto has one thing in common with Earth: a blue sky.

New horizons

The spacecraft that flew past Pluto in July of last year is now on a new mission. Extended through at least 2019, when New Horizons will encounter 2014 MU69—just thirty miles wide and probably more pristine. Along the way, we may get a long-range view of dwarf planet Eris and perhaps many smaller bodies. New Horizons has a lot left to show us.

Gran Quivira will present two star party events in August

On August 2, there will be a Sunset Missions Tour. Meet at the  GQ Visitor’s Center at 7:15 p.m. This will be followed by an astronomy talk with telescopes. This event will go until 11:00 p.m.

On August 12, with its 360-degree views and dark skies, the Gran Quivira Ruins will provide a spectacular backdrop for viewing the Perseid Meteor Shower. This year, the Perseids will be in “outburst,” meaning that the meteors will appear at double the normal rates (we could see 150 and possibly even two hundred meteors per hour).

The Sunset Missions Tour meet at the GQ Visitor’s Center at 7:00 p.m.; Meet at 9:00 p.m. for the Perseid Program. The GQ Visitor’s Center is located at the Salinas Pueblo Missions National Monument near Mountainair, New Mexico.

For further information, contact Bethany Burnett at 847-2770


 
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