Saturday, October 16, 2010
While on the 12th of October we had an interesting close approach (50,000 km or so) with a small asteroid called 2010 TD54 with a diameter of just 10 metres or so, it turns out that a day before that another asteroid flew by the Earth at a distance of some 350,000 km (90% the distance from here to the Moon), we just didn't know about it until two days after it flew by. This is a common occurrence with asteroids of that size that come at us from the direction of the Sun, as its glare makes it hard to find and then as soon as it passes by, voilà it's away from the Sun and is being lit up very well from behind.
Asteroid 2010 TN55 is also fairly small, somewhat larger but only about 16 metres in diameter. In terms of mass though it would be about four times the other one. Its orbit is here, an interesting elliptical one that carries it in almost as close as Mercury, but then out nearly as far as Jupiter at aphelion.