Sonda Messenger em Mercúrio - 2008

Luis França

Nimbostratus
Registo
23 Mai 2006
Mensagens
1,467
Local
Hades
Messenger probe shows off side of Mercury never seen before

art.mercury.spider.ap.jpg


WASHINGTON (AP) -- The first pictures from the unseen side of Mercury reveal the wrinkles of a shrinking, aging planet with scars from volcanic eruptions and a birthmark shaped like a spider.
Some of the 1,213 photos taken by NASA's Messenger probe and unveiled Wednesday help support the case that ancient volcanoes dot Mercury and that it is shrinking as it gets older, forming wrinkle-like ridges. But other images are surprising and puzzling.

The spidery shape captured in a photo is "unlike anything we've seen anywhere in the solar system," said mission chief scientist Sean Solomon of the Carnegie Institution of Washington. The image shows what looks like a large crater with faint lines radiating out from it.

Mercury, the closest planet to the sun, has often been compared to Earth's dull black-and-white moon. But the new photos, which reveal parts of Mercury never seen, show the tiny planet is more colorful and once had volcanic activity.
 

Luis França

Nimbostratus
Registo
23 Mai 2006
Mensagens
1,467
Local
Hades
Mercury's 'tail' is longer than thought

Mercury's gravity is too weak to hold a permanent atmosphere, so when atoms are evaporated from the planet's surface by solar photons or other processes, some of the atoms form a tail that points away from the sun.

Jeffrey Baumgardner and colleagues at Boston University's Center for Space Physics studied the bright yellow-orange light emitted by the sodium atoms in Mercury's tail and discovered the tail, previously detected to 15 times the radius of Mercury, actually extends more than 100 times that distance, or 1.6 million miles from the planet.

The physicists also discovered the time it takes for the sodium atoms to leave Mercury's surface and reach the tail's maximum length is approximately 15 hours.

The research by Baumgarder, Jody Wilson and Michael Mendillo appears in the journal Geophysical Research Letters.