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1. Rosendo Franco rhf375
Astronomy
20 October 2016
Writing Assignment
Thanks to all the information pouring in from NASA’s New Horizons mission, Pluto is
making a comeback. As New Horizons principle investigator Alan Stern says, “Pluto is the new
Mars” – and that’s not just because of its rising popularity.
The nickname, which Stern credits fellow New Horizons team member Jeff Moore with
bestowing, comes in part from several intriguing similarities the distant icy world shares with the
famous red planet. Both boast an array of surface and atmospheric puzzles sure to keep scientists
intrigued for some time.
“There are really so many ways Pluto reminds us of Mars,” says Stern.
Puzzling atmospheric questions linger over Mars and Pluto. For Mars, the questions
involve how its atmosphere disappeared and what that meant for any liquid on the planet’s
surface. Pluto is also losing its atmosphere, but at a far slower rate than scientists expected before
New Horizons arrived. According to Stern, the atmosphere is escaping about 500 times slower
than estimated before the flyby.
That may come from a cooler-than-expected upper atmosphere, which slows down how
much material is lost. Something in the air is keeping things chilly, but exactly what remains
unknown. “We are still searching for that mystery molecule that can explain this much cooler
upper atmosphere,” Stern said.
A mystery molecule isn’t the only thing floating in the air. Pluto, like Mars, has a handful
of tenuous clouds. On both planets, the clouds could suggest unusual weather patterns that, at

2. least on Pluto, were unexpected.
Like Mars, Pluto may have had a much thicker atmosphere in its past. With an orbit of
almost 250 years, temperatures on the dwarf planet can vary significantly over its year, allowing
the atmosphere to pile up. A thicker atmosphere could affect how material on the surface
behaves. Some of the terrain features suggest that Pluto may have once had liquid pooling on and
running across its surface, Stern said.
One of the most striking features on Pluto is its giant heart-shaped basin, informally
dubbed by the team as Tombaugh Regio. Like Hellas Basin on Mars, the memorable landmark
was most likely caused by a massive object striking the planet. Speaking at the American
Astronomical Society’s Division for Planetary Sciences meeting in Pasadena, California, Stern
blamed a 40- to 60-kilometer Kuiper Belt object for carving out Pluto’s heart.
Mars has kept the world intrigued with increasing evidence that water flowed across its
surface, and suggestions that it may still occasionally trickle today. While Pluto is too cold for
water, its features also show evidence of sculpting by easily evaporated materials known as
volatiles. For Pluto, the volatile of choice is nitrogen ice.
The northern “lobe” of the heart, Sputnik Planitia, is made up of frozen blocks of
nitrogen ice.(Formerly known as Sputnik Planum, the feature is now known to be a sunken plain,
or planitia, rather than a raised plain, or planum, Stern said.) After the impact excavated the
basin, the volatile material rushed to fill the void.
Sputnik Planitia also boasts glaciers not unlike the polar glaciers of Mars. New Horizons
revealed that glaciers around the heart of ice flowed recently, and could still be flowing today,
despite Pluto’s frigid temperatures. Like Mars, the glaciers are affected by sunlight, but Pluto’s
longer trip around the sun means that the glaciers spend more time both in and out of the rays,

3. and its distance minimizes the effects compared to its sibling.

4. https://www.nasa.gov/feature/new-horizons-possible-clouds-on-pluto-next-target-is-
reddish
http://www.astronomy.com/news