Slashdot Mirror
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
I think the "moon" label is very inaccurate. It's not orbiting anything but the Sun. It's also, as you noted, much farther away than our own moon. According to the Java applet (which is pretty cool, btw) the asteroid will be on the other side of the sun for a lot of the time (and even outside the orbit of Mars).
Catchy, but misleading headline. Still pretty neat, though.
And this is a dupe from 4 years ago.
Earth's Second Moon 2nd Moon Orbiting Earth Discovered
SW = Star Wars. I hope you were joking, because that's just sad.
There is an entire branch of astronomy that uses distributed observations to map the size and shapes of asteroids using occultations (eclipses with distant stars). When an asteroid passes in front a distant star, the star winks out and then reappears. Knowing the duration (start and stop times) of the occultation, the location of the observer, and the orbits of the Erath and asteroid lets people estimate the size and shape of the asteroid. International Occultation and Timing Association collects data from telescopes around the world (many in the hands of hobbyists) and uses the data to make these estimates.
Two wrongs don't make a right, but three lefts do.
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
The kind that you wouldn't be able to detect (except maybe by careful monitoring of the sun with a well-filtered telescope pointed at exactly the right spot). Imagine something much smaller than the moon and even farther away passing in front of the sun. That's what this is.
To experience a solar eclipse from a temporary sattelite would be a once-in-a-lifetime experience.
If it were noticeable. But temporary satellites (like the ISS) cast (highly-attenuated) shadows on the Earth every day.
http://alternatives.rzero.com/
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
I was looking at the orbits of Pluto and Neptune on the applet, and noticed that Pluto is shown as inside Neptunes orbit at present and until 2011, but I was under the impression that Pluto was once again the farthest planet, as of 1999, and wouldn't pass in again until 2226. So I'm not sure their orbits are correct....
Nah, he'd still be scratching his head at the whole "precession of Mercury" thing.
Actually the horseshoe shape is only its path relative to Earth. Its path relative to the sun is much more mundane.
DNA just wants to be free...
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...
"while it orbits the sun on a horse-shoe shaped path"
Uh, wouldn't it be easier to fly an elliptical orbit?
The simulator link is incorrect. It points to 2004 YN1. The correct link. For a good view in the simulator, tilt the 3D view to straight down, center on earth and zoom in all the way.
New Scientist has an interesting article in their latest issue.
For a more technical explanation, read the paper presented at the Lunary Planetary Science Conference last week.
With a little more specificity, if this object is m=24, then it's about (24-7)=17 magnitudes fainter than the *best* that the human eye can do. To put that into perspective, given that five magnitudes of difference is about 100x difference in actual brightness (~2.5^5), a difference of 17 magnitudes is *roughly* 5.8E6 (2.5^17) times fainter than the human eye is capable seeing in optimal, dark-sky conditions.
Also, see: International Dark-Sky Association
No gods, no demons, and no masters. Secular Humanism!
The picture on the Discovery Channel coverage is not the asteroid in question. I know this means I need to get out more, but I instantly recognized that picture as 243 Ida and its tiny satellite Dactyl.
Ydco co
You've described the mass driver, the standard asteroid/ore moving workhorse of the O'Neill/L5 space colonization effort.
It works like this: picture a bucket on a recirculating rail. The rail is pretty long, hundreds of feet at least. The bucket meglevs along the rail.
There would be at least three railguns on the asteroid, pointing away from the asteroid in opposing directions. Actual orientation is not that important, what is important is that the rails point away.
In operation, the "bucket" stops at a point along the rail on the surface of the asteroid. Some mechanism plonks a pound or so of rock into the bucket. The bucket locks the material down.
The bucket now electromagnetically moves away to the railgun run. On reaching it, it accelerates. At an approprate time, it releases the payload. The bucket slows down, and returns to the loading point.
The process changes the the path of both the payload (reaction mass) and to the asteroid itself. Repeat this process millions of times, and you alter the asteroid's orbit.
The beauty part of a mass driver is that it has no moving parts in contact. You just need something to shovel in the reaction mass, and electricity to run the linear accelerators.
Asteroids can be moved in this manner. Rockets won't hack it, nor ion engines, nor nuclear explosions. Lack of control, or raw power.
We could shape the orbits of these Earth grazers to bring them a little closer to home so that we can exploit them for raw materials to build habitats, build ships, build elevators.
Space elevator projects require a large mass at the opposite end of the tether from the surface to anchor the cable. Asteroids have been suggested for the necessary mass. Mass drivers are the way to go if you want to get that mass.