Two newly discovered asteroids to pass by the Earth on the same day - today

Wednesday, September 08, 2010

As is often the case every few months, we've been surprised with the close approach of an asteroid that we knew nothing about until just a short while ago...except that this time it's two, not one. The two asteroids have the following dimensions and trajectories (the second and third on the chart):


Object
Name
Close
Approach
Date
Miss
Distance
(AU)
Miss
Distance
(LD)
Estimated
Diameter*
H
(mag)
Relative
Velocity
(km/s)
(2010 LY63) 2010-Sep-070.143956.0740 m - 1.6 km17.88.22
(2010 RX30) 2010-Sep-080.00170.610.0 m - 22 m27.110.00
(2010 RF12) 2010-Sep-080.00050.25.8 m - 13 m28.36.00
(2010 PR10) 2010-Sep-100.090535.2110 m - 250 m21.95.00
(2007 VG189) 2010-Sep-130.172567.1360 m - 810 m19.310.09

So both of them are passing by closer than the Moon (Moon = 384 000 km), which is a very close graze in astronomical terms.

And for all we know we have another two on their way to Earth right now, due to arrive in a week. Or a month, or two. It's impossible to tell until we get a probe out there capable of looking back on the Earth instead of having to detect asteroids that are located between us and the Sun's glare, but too small to detect when they are far away. The way they work is as follows: 1) spend years and years orbiting the Sun at a distance too far away for us to detect given their small size, 2) begin the process of moving closer and closer to the Earth, but as a result are now very close to the Sun from our perspective, thus still invisible, and then 3) now just a few days or hours away from closest approach, all of a sudden we are capable of spotting the asteroid. Announce the close approach, hurriedly try to observe it as it goes by. See, here's where the smaller one was back in mid-July:

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