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Earth Acquires a Quasi-Moon
richard_za writes "Earth has acquired a so called quasi-moon, an asteroid: 2003 YN1, which will encircle us for the next couple of years while it orbits the sun on a horse-shoe shaped path. Full story on News24. It was found by team led by Paul Chodas, an asteroid specialist at Nasa's Jet Propulsion Laboratory in California. An orbit simulation can be seen in this Java applet."
Here's a link to Discovery Channel's coverage without the need for registration.
Mike
According to the Discovery Channel article linked elsewhere, 2003 YN17 is at least the fourth moon. The three others are the real moon (Luna, as some call it), Cruithne, and 2002 AA29.
Have the other two left already/have there been others in the past?
This is the third asteroid we've found which has an orbit tied loosely to that of the Earth. The others are 3753 Cruithne and 2002 AA29. You can see pictures and applets and read about these other bodies at Paul Wiegert's web site:
http://www.astro.uwo.ca/~wiegert/
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
Our plain old moon orbits the sun, too. The sun pulls on it with twice the force of the Earth. The Earth merely perturbs the moon's orbit around the sun enough to make it look wobbly. In fact I just found out that Earth's moon is unique in this respect by reading this page about planets and moons!
What a fool believes, he sees, no wise man has the power to reason away.
According to the article, the magnitude is around 24. The best the human eye can see is about magnitude 5 given excellent conditions.
:
It is essentially invisible unless you have a decent research telescope.
More info on the astronomical magnitude scale can be found here
http://cfa-www.harvard.edu/icq/MagScale.html
Actually, believe it or not Luna's orbit is also more influenced by the Sun than the Earth -- if you trace out its path relative to the Sun, it makes an ellipse, not a ... bleah, forget the name of the shape. Anyway, there aren't any loops in evidence.
From a mathematical standpoint, it would be more appropriate to say that Luna orbits the Sun, rather than that it orbits the Earth.
That said, the Earth+Luna system still has a combined center of gravity which lies beneath the Earth's surface, so in that sense at least Luna is still Earth's satelite.
DNA just wants to be free...