A picture to assist the description.
Posted on 07/28/2011 4:40:22 AM PDT by Lonesome in Massachussets
The asteroid in the Earth's orbit around the sun has been hiding from view, mostly overhead during daylight, study finds.
Turns out the moon's not the Earth's only traveling companion. Space scientists have discovered an asteroid that's been following our fair planet for thousands of years, at least — and there may be many more where it came from, according to a recent study.
(Excerpt) Read more at latimes.com ...
Nice article. Don't use her explanation of Lagrange points on your astrodynamics final, however.
Earth Trojans have been speculated about as least since Jovian Trojans were discovered in the 19th Century. The maximum elongation (angular separation) of Venus is no more than about 60 degrees, so apparent distance from the sun is not a good explaination for not discovering them sooner, at least to me. One camp will set four hours after the sun, the other will rise four hours before him.
There are five Lagrange points, labeled L1, L2, L3, L4 and (wait for it) L5. The L3 and L4 points share the earth's orbit. A body in the L3 or L4 point would circle the sun in the same orbit as the earth, but precede or lag the earth by 60 degrees or about 60 days days. The L3 and L4 points are stable orbits because if a body is perturbed off that point, it will be strongly drawn back. In fact, Jovian Trojans do not sit at the Lagrange point, but oscillate or "librate" about it.
Trojans sharing the Moon's orbit have been pretty much ruled out because they could not survive the disruptions caused by that fourth body, the sun. Some have speculated that Venus would destabilize Earth-Sun Trojans, but maybe not, or maybe this is only a short term relationship. There is at least one asteroid in a horseshoe orbit with the earth.
"There are more things in Heaven and Earth, Horatio..."
Interesting trivia fact: The asteriods in the Jovian L3 and L4 points are named for characters in the Trojan Wars. The characters in one point are mainly named for Greeks and the other for Trojans. The two points are refered to as the "Greek camp" and the "Trojan camp" for this reason. Hence the name for asteriods in L3 and L4 points is "Trojans".
Earth hasn’t cleared its orbit!
/ bad joke.
/mark
I promise I will NEVER use her explanation of Lagrange points on ANY astrodynamics final.
These Trojan asteroids are doubtless on the Interplanetary_Transport_Network: it ought to be relatively inexpensive to drop an automated probe close to them.
A picture to assist the description.
Note to all, that image is not drawn to scale.
If they are overhead during the day, where are they at night?
Is it true there are a lotta nice girls just outside Lagrange?
Have mercy. I know what you’re talkin’ about.
Rumor. They are mostly out of work female liberal reporters replaced by strangers in an increasingly strange land.
there. that's done.
Will be there in August & let you know.
Take a look at the diagram with all the gravity lines a couple of responses up from your question. Anything at points 1, 3, 4, and 5 will stay there, and as you will rotate to the opposite side of the Earth at night, you won’t be able to see them.
Your question is the same as, “If the Sun is overhead during the day, where is it at night?” We turn our back on it.
My apologies. I thought it was an real question (I’ve seen worse...) Have a great weekend.
Another, even better, article on the same topic. You can take this guy’s astrodynamics to the bank:
http://www.skyandtelescope.com/news/home/126298103.html
BTW, you may have noticed that what I called the L3, L4 Lagrange points should have been L4 & L5. Thank you for your indulgence in not correcting me.
That would have been a first. :’)
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Glad that’s been taken care of.
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