Asteroid 2005 YU55 is almost here!

Friday, October 28, 2011

At long last, we're finally going to have a close encounter with the quite large (400 metres in diameter) asteroid 2005 YU55. I mentioned it here and here before, but now we only have a week and a bit left to wait.'s article on the asteroid is quite exciting to read.

With an asteroid this large and a miss distance less than that from the Earth to the moon, this asteroid encounter is basically a flyby for free, but with all the available instruments from Earth turned on it instead of the resources of a single probe. Last year when it passed by at a distance a bit more than five times the Earth to the moon, it looked like this:

So what kind of resolution are we looking to end up with? Well:

"Goldstone will begin observations on Nov. 4 and Arecibo on Nov. 8. Goldstone hopes to get 2- meter resolution from the resulting shape model – which is quite remarkable and comparable, or better than, what would be expected from spacecraft flyby imaging," Yeomans told

Finally, how large is the surface area of this asteroid? As I often note with irritation, nobody seems to want to give the approximate surface area for asteroids, leaving us without an idea of what it would be like to stand on the surface. 2005 YU55 has a diameter of 400 metres, meaning that the surface area is around 500,000 m2, or half a square kilometre. That's a bit more than Vatican City. Or with a circumference of 1.2 km it would take about 20 minutes to 'walk' around back to the point where you started.

Observations begin Nov. 4 (radio observations), and continue a few days past Nov. 8!


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