Sunday, December 11, 2011

Asteroid Crash May Explain Mercury's Strange Spin

Date: 11 December 2011 Time: 01:00 PM ET
SHARE
Facebook
First high-resolution image of Mercury transmitted by the MESSENGER spacecraft (in false color, 11 narrow-band color filters).
First high-resolution image of Mercury transmitted by the MESSENGER spacecraft (in false color, 11 narrow-band color filters).
CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A collision with an asteroid might have set the planet Mercury whirling oddly in its orbit, a new study suggests.
When one body orbits another — say, a moon around a planet or a planet around a star — the orbiting body often spins. Our planet experiences day and night because it spins on its axis, regularly changing which side it exposes to the sun.
However, the gravitational pull that orbiting moons and planets experience slows the rate of their spin. The most stable arrangement they can reach is to keep just one side always facing the body they are orbiting. Such "tidal locking" is why our moon always keeps the same face pointed toward Earth.

MORE: http://www.space.com/13889-mercury-spin-asteroid-collision-tidal-locking.html

gaw

Glenn A. Walsh, Project Director,
Friends of the Zeiss < http://friendsofthezeiss.org >
Electronic Mail - < gawalsh@planetarium.cc >
SPACE & SCIENCE NEWS, ASTRONOMICAL CALENDAR:
  < http://buhlplanetarium.tripod.com/#news >
Twitter: < http://twitter.com/spacewatchtower >
Facebook: < http://www.facebook.com/pages/SpaceWatchtower/238017839577841?sk=wall >
Blog: < http://spacewatchtower.blogspot.com/ >
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >

No comments:

Post a Comment