Asteroid 2005 YU55
What is bigger than Apophis and will arrive on November 8, 2011?
And no one is talking much about it.
This asteroid, first discovered in December of 2005, remains mostly a mystery. Even its size is a guess. What’s not a guess is when it will arrive again in the vicinity of earth.
The object was monitored a total of 42 times between December 28th 2005 and January 23rd of 2006. Since then, this object has been speeding along its orbit around the sun, out of sight. The next opportunity to view this asteroid will come in less than a year, on April 19th of 2010. It will pass, according to estimates somewhere between the earth and the moon. The distance for the April, 2010 encounter is estimated at around 150,000 miles.
The estimate for the November 8, 2011 visit is guessed at around 95,000 miles. That close, but it doesn’t sound too close, it will probably just fly right by, no problem for us. But wait a minute, before you get too comfortable, these estimates are based on a very short observation period and in fact, these numbers are just estimates, educated guesses at best.
2005 YU55 Orbit
Apophis was big news a few years ago when it was predicted to hit in 2029. Much more is known about Apophis than 2005 YU55 and now it is said that Apophis will miss in 2029. The size of Apophis is estimated to be about 270 meters across, about 885 feet. 2005 YU55 is estimated to be as large as 280 meters or 918 feet.
Certainly not big enough to be a planet killer. Worst-case scenario, using the given estimates of size, the most thing could do would be to wipe out an area around 900 square miles. It’s certainly enough to take out any city along with all of the suburbs. It would leave a crater about four times the size of the meteor crater in Arizona.
Meteor Crater, Arizona
The problem with 2005 YU55 is that so much is up in the air. The actual size estimate given by astronomers is between 120 and 280 meters, that’s more than a 100% difference between the upper and lower estimate. Even if the estimates on its orbit are correct, this thing has been left unattended in space for over three years. It will have been out of sight for over 4 years when it returns in April of next year. How would its orbit change if it were to have a collision with some small object during this time?
We will certainly learn more about this asteroid in April 2010 when it returns. Chances are nothing will happen at all. With any luck this will just pass us by like so many that have come before. Everyday on earth we take part in a cosmic lottery of sorts. Problem is, no one wants to collect the grand prize. Some day though, we will collect that prize. Let just hope it’s not in out lifetime.
Big rock heading toward Earth: Enjoy the view
- Phil Plait
The near-Earth asteroid 2005 YU55 YU55, on the list of potentially dangerous asteroids. (Arecibo Observatory/Michael Nolan)
On November 8, an asteroid 400 meters across will pass by the Earth, missing us by the very comfortable margin of about 320,000 kilometers (200,000 miles). Named 2005 YU55, it’s been known for some time that this pass will occur, and astronomers are jumping on the chance to observe it.
First off, it’s no danger to Earth right now. It’s what’s called a Potentially Hazardous Asteroid because its orbit intersects ours, but observations have shown it won’t be a danger to Earth for at least a century, and probably much more. There’s been some scare-mongering about it over the past few months, but as usual that’s all baloney. This rock will pass us safely, sailing on into the night.
But given that this is close in astronomical terms, astronomers will be observing it carefully. There are plans to use NASA’s Deep Space Network of radio telescopes, as well as the Arecibo ‘scope in Puerto Rico (which was used to make the image above back in April 2010). They’ll be able to see features on this rock as small as two meters across, which means we’ll actually get some interesting images of it, I hope. I’ll post those as soon as I see ‘em (which will be after November 8).
It’ll only get to a magnitude of about 11 — only 1/100th as bright as the faintest star you can see with your unaided eye — so you’ll need a decent-sized (12.5 cm at least) telescope to see it. 320,000 km is 3/4 of the way to the Moon, and this asteroid is small and very dark. Observing it will be tough, but you can get more info on how to do it at the Minor Planet site and on The Minor Planet Bulletin (PDF).
When I was a kid, asteroids were not much more than mysterious points of light, but now we have the technology to see them in detail from the ground, and even send space probes to get good, close looks at them! And, of course, the technology to spread those images and information as quickly as the speed of light around the globe. Sometimes that’s used to spread misinformation, but it also can be used to show people what a cool place we live in. I prefer the latter.