Subscribe free to our newsletters via your
. 24/7 Space News .




OUTER PLANETS
The Lower Atmosphere Of Pluto Revealed
by Staff Writers
Paris, France (ESA) Mar 03, 2009


Artist's impression of how the surface of Pluto might look, according to one of the two models that a team of astronomers has developed to account for the observed properties of Pluto's atmosphere, as studied with CRIRES. The image shows patches of pure methane on the surface. At the distance of Pluto, the Sun appears about 1000 times fainter than on Earth.

Using ESO's Very Large Telescope, astronomers have gained valuable new insights about the atmosphere of the dwarf planet Pluto.

The scientists found unexpectedly large amounts of methane in the atmosphere, and also discovered that the atmosphere is hotter than the surface by about 40 degrees, although it still only reaches a frigid minus 180 degrees Celsius.

These properties of Pluto's atmosphere may be due to the presence of pure methane patches or of a methane-rich layer covering the dwarf planet's surface.

"With lots of methane in the atmosphere, it becomes clear why Pluto's atmosphere is so warm," says Emmanuel Lellouch, lead author of the paper reporting the results.

Pluto, which is about a fifth the size of Earth, is composed primarily of rock and ice. As it is about 40 times further from the Sun than the Earth on average, it is a very cold world with a surface temperature of about minus 220 degrees Celsius!

It has been known since the 1980s that Pluto also has a tenuous atmosphere, which consists of a thin envelope of mostly nitrogen, with traces of methane and probably carbon monoxide. As Pluto moves away from the Sun, during its 248 year-long orbit, its atmosphere gradually freezes and falls to the ground.

In periods when it is closer to the Sun - as it is now - the temperature of Pluto's solid surface increases, causing the ice to sublimate into gas.

Until recently, only the upper parts of the atmosphere of Pluto could be studied. By observing stellar occultations (ESO 21/02), a phenomenon that occurs when a Solar System body blocks the light from a background star, astronomers were able to demonstrate that Pluto's upper atmosphere was some 50 degrees warmer than the surface, or minus 170 degrees Celsius.

These observations couldn't shed any light on the atmospheric temperature and pressure near Pluto's surface. But unique, new observations made with the CRyogenic InfraRed Echelle Spectrograph (CRIRES), attached to ESO's Very Large Telescope, have now revealed that the atmosphere as a whole, not just the upper atmosphere, has a mean temperature of minus 180 degrees Celsius, and so it is indeed "much hotter" than the surface.

In contrast to the Earth's atmosphere, most, if not all, of Pluto's atmosphere is thus undergoing a temperature inversion: the temperature is higher, the higher in the atmosphere you look. The change is about 3 to 15 degrees per kilometre. On Earth, under normal circumstances, the temperature decreases through the atmosphere by about 6 degrees per kilometre.

"It is fascinating to think that with CRIRES we are able to precisely measure traces of a gas in an atmosphere 100 000 times more tenuous than the Earth's, on an object five times smaller than our planet and located at the edge of the Solar System," says co-author Hans-Ulrich K�ufl. "The combination of CRIRES and the VLT is almost like having an advanced atmospheric research satellite orbiting Pluto."

The reason why Pluto's surface is so cold is linked to the existence of Pluto's atmosphere, and is due to the sublimation of the surface ice; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. In this respect, Pluto shares some properties with comets, whose coma and tails arise from sublimating ice as they approach the Sun.

The CRIRES observations also indicate that methane is the second most common gas in Pluto's atmosphere, representing half a percent of the molecules. "We were able to show that these quantities of methane play a crucial role in the heating processes in the atmosphere and can explain the elevated atmospheric temperature," says Lellouch.

Two different models can explain the properties of Pluto's atmosphere. In the first, the astronomers assume that Pluto's surface is covered with a thin layer of methane, which will inhibit the sublimation of the nitrogen frost. The second scenario invokes the existence of pure methane patches on the surface.

"Discriminating between the two will require further study of Pluto as it moves away from the Sun," says Lellouch. "And of course, NASA's New Horizons space probe will also provide us with more clues when it reaches the dwarf planet in 2015."

.


Related Links
the missing link The million outer planets of a star called Sol






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








OUTER PLANETS
1,000 Days On The Road To Pluto
Washington DC (SPX) Oct 08, 2008
It's hard to believe, but Oct. 15 will be the 1,000th day of flight for New Horizons. And in that time we've traveled so far that only four other spacecraft - Pioneers 10 and 11 and Voyagers 1 and 2 - have ventured farther. Can you believe it's been this long? Sometimes it seems so, but other times, it seems like we just blasted off from Florida on that cool afternoon of Jan. 19, 2006. ... read more


OUTER PLANETS
China To Land Probe On Moon At Latest In 2013

Help To Define A Lunar Lander

What Is The Story Behind The Dark Side Of The Moon

Obama's First Budget Backs Core Lunar 2.0 Goals

OUTER PLANETS
Gullies On Mars Show Tantalizing Signs Of Recent Water Activity

Final European Crewmembers Announced For Human Mars Mission Simulation

Final European Crewmembers Announced For Human Mars Mission Simulation

Orbiter Puts Itself Into Precautionary Mode

OUTER PLANETS
NASA Tests Parachute For Ares Rocket

Oceaneering To Develop And Produce Constellation Space Suit System

Statement About NASA Budget Overview For FY2010

NASA budget request totals $18.7 billion

OUTER PLANETS
New Space Launch Center To Be Built In China's Southernmost Hainan

China's New Geo-Stationary Weather Satellite Finishes Testing

China Plans Space Station With Module Launch In 2010

China Plans To Launch Third Ocean Survey Satellite In 2010

OUTER PLANETS
Second ATV Named After Johannes Kepler

Russian supply craft arrives at space station: agency

Satellite collision poses 'small' risk to ISS: NASA

Columbus, One Year On Orbit

OUTER PLANETS
The Case Of The Fairing That Would Not

NASA Kepler Telescope To Launch Aboard Delta II Rocket

DPRK Shows Tough Stand On Satellite Launch

Russia Set To Put US Telecom Satellite Into Orbit

OUTER PLANETS
Launch Cover Placed Over Kepler

Kepler Attached To Rocket

Counting On Kepler

Boulder Students To Be At Controls For Kepler Mission

OUTER PLANETS
NKorea testing radar ahead of planned launch

Telstar 11N Satellite On Track With Post Launch Maneuvers

Ball Aerospace Completes OMPS Integration For NPP

An Impossible Alloy Now Possible




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement