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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 2015 night sky

—Charlie Christmann

All eyes on Pluto:

All of astronomy is focused on Pluto this month as the NASA probe New Horizons whooshed by the former planet and its moons. While many planetary scientists speculated on what they would find, Pluto has already provided many surprises that no one anticipated, even though only a tiny fraction of the data has been transmitted.

The spacecraft had to do its work quickly as it flew through the Pluto system at more than thirty thousand miles per hour on July 14. As of July 20, New Horizons was already more than 4.6 million miles beyond Pluto, or 2.95 billion miles from Earth. At that distance, radio signals take four hours and 26 minutes to travel to NASA’s deep space receivers. While data is still being collected by the craft as it speeds away, an estimated five gigabytes of data has been collected. Because of the distances involved and the radio signals equivalent to a nightlight incandescent bulb, about ten watts, the data rate is a little over one thousand bits per second per channel. With two channels available, it will require about 88 days to transmit the data and high-resolution images home.

The images received so far are from low resolution. These could be sent home quickly just in case something went wrong. But these images are already throwing scientists curve balls. Many expected to find a cratered surface on both Pluto and its largest moon Charon, but they found both have only a few.

The most striking feature seen as New Horizons approached the dwarf planet was the reddish brown color and a large heart-shaped lighter-colored region, now named ‘Tombaugh Regio’ after Pluto’s discoverer. Within this region, small snippets of higher-resolution pictures show the ice mountains of ‘Sputnik Planum’ and icy plains of ‘Norgay Montes.’ Images of Sputnik Planum look like white mud after it has been baked by the sun—cracked into plates. Some plates have hills and mountains in the middle of the cracks. Some of the deeper cracks show a darker material in the bottom. The white frost is most likely carbon monoxide freezing out of the tenuous atmosphere. There are also hints of dark streaks that may have resulted from something erupting from within, though no geysers have been seen … yet.

On Charon, one strange feature stands out: a mountain in a moat and a darker polar cap. About the only thing scientists can say about the polar cap is that it is big and red. As for the mountain, no one seems to have an explanation as to how it formed.

After passing Pluto, New horizons turned its attention to the thin Pluto atmosphere. Interestingly, the spacecraft found a tail of ionized gas streaming away representing five hundred tons every hour. Pluto, even at a surface temperature of negative 369 degrees Fahrenheit, is slowly evaporating! Fortunately for it, Pluto is leaving the inner solar system for the Kuiper Belt where the atmosphere will again freeze and turn to a layer of snow on the surface. In another two hundred years, Pluto will again cross Neptune’s orbit and form an atmosphere and evaporate a little bit more.

If the small bit of information we have seen so far is any indication, the future images and data received from the craft are sure to amaze and confound.

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