Posted by
CowboyNeal
on from the heavenly-bodies dept.
loconet writes "The BBC is reporting that astronomers have discovered the first object ever that is in a companion orbit to the Earth. Asteroid 2002 AA29 is only about 100 metres wide and never comes closer than 3.6 million miles to our planet."
Earth's second moon
by
EggplantMan
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· Score: 5, Interesting
Not only is it co-orbital but it periodically gets trapped in earth's gravitational field to become a second moon:
General Simon Worden of the United States Space Command described it as a "near Earth object that is close to being trapped by the Earth as a second natural satellite".
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In 550AD, and again in 2600AD and 3880AD, for a while it will become a true satellite of our planet, in effect Earth's second moon, although technically it will remain under the gravitational control of the Sun.
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600 years?
by
cybermace5
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· Score: 5, Interesting
They claim it will be temporarily in earth orbit by 2600 AD. And then they go on to speculate on how important that would be to space exploration, possibly becoming the second object visited by astronauts.
If, in 600 years, we haven't sent astronauts to visit other planets, I have preemptively lost faith in the human race.
Come on, in 600 years we should have a pretty decent Mars colony going.
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Re:Not quite a planet, eh?
by
jamie
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· Score: 5, Interesting
"In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit."
No, any object in the same orbital path travels the same velocity.
Think about it this way. If I have a heavy object and a light object orbiting at Earth's distance from the sun, by your hypothesis one will travel faster than the other. So if I duct-tape them together they should travel at a speed somewhere in-between the fast one and the slow one. But the taped-together object masses the sum of both smaller objects so it should travel faster. It can't travel both faster than and slower than its larger half, so the hypothesis can't be right.
Zookeeper Hypothesis
by
gnarly
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· Score: 5, Interesting
The Fermi Paradox asks: If intelligent life is common, given the billions of years since the formation of our galaxy, why have E.T.'s not yet reached (and perhaps colonized) Earth?
One proposed resolution is the Zookeeper Hypothesis, ie, they could have contacted us but are just waiting and watching for us to evolve, a la 2001.
If so, then wouldn't they want to put a probe near the Earth, which swoops down every few centuries or so for a close look, to see if any thing interesting has happened?
-- :-( is a registered trademark of Despair.com
Confused...
by
abhinavnath
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· Score: 5, Interesting
How is this object considered a "companion" while Cruithne - Earth's "second moon" - is not?
Slashdot Mirror
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They claim it will be temporarily in earth orbit by 2600 AD. And then they go on to speculate on how important that would be to space exploration, possibly becoming the second object visited by astronauts.
If, in 600 years, we haven't sent astronauts to visit other planets, I have preemptively lost faith in the human race.
Come on, in 600 years we should have a pretty decent Mars colony going.
...
No, any object in the same orbital path travels the same velocity.
Think about it this way. If I have a heavy object and a light object orbiting at Earth's distance from the sun, by your hypothesis one will travel faster than the other. So if I duct-tape them together they should travel at a speed somewhere in-between the fast one and the slow one. But the taped-together object masses the sum of both smaller objects so it should travel faster. It can't travel both faster than and slower than its larger half, so the hypothesis can't be right.
One proposed resolution is the Zookeeper Hypothesis, ie, they could have contacted us but are just waiting and watching for us to evolve, a la 2001.
If so, then wouldn't they want to put a probe near the Earth, which swoops down every few centuries or so for a close look, to see if any thing interesting has happened?
How is this object considered a "companion" while Cruithne - Earth's "second moon" - is not?
Earth's Second Moon
2nd Moon Orbiting Earth Discovered
Google Search: Cruithne
Is there an astronomer in the house? Or anybody who could clarify this?
My other sig is also a