POSSIBLE ASTEROID IMPACT ON THE MOON?UPDATE SEPTEMBER 9 -
No reports of the asteroid have been received nor posted since the close earth-moon flyby; efforts to locate the asteroid just after its predicted close pass have been unsuccessful.
So, it has either moved rapidly into deep space beyond the reach of large telescopes, or it perhaps could have impacted the far side of the moon.
You read that headline right, although the chances are probably quite remote. We have a new close-approaching asteroid, 2016 RB1, that was just discovered and confirmed the past two days as approaching the earth very closely - an estimated 24,000 miles distant at closest pass.
All interest in this object has shifted, however, as possibly flying by so close that it might be perturbed graviationally to impact with the MOON tomorrow, September 8, at around sunrise in the northern hemisphere. Such an event would of course be extremely rare and would cause great interest and response to the possible consequences of such an impact.
2016 RB1 is an estimated 6-15 meters in diameter, but at its speed of approach would make quite a visible imact against the moon if such would happen.
From a message by orbital astrophysicist Bill Gray of Project Pluto as he posted on he Yahoo MPML forums:
"I see I'm not the only one checking encounter distance with the moon...
I keep hoping for an observable impact. It's quite long odds. The
moon has 1/4 our diameter, therefore 1/16 the "capture area"; we've
an observational bias toward things coming close to us, more so than
things coming toward the moon; and we have enough mass so that a
near-miss can be pulled down into an impact, more so than the moon
does. So far, I haven't seen a natural object come close enough
to the moon for me to even mention the fact.
....... H=27.9, making for a size of 6 to 15 meters (assuming
albedoes of 0.50 or 0.05).
It'll be nicely placed to be observed from Australia and New Zealand,
and not too bad from South Africa. (It would help to have a few more
observations soon, though. The ephemeris near perigee is a little
rough right now, with positional uncertainties of several degrees.)
Unfortunately, Northern Hemispherians don't get such a great view of
it; the object passes almost directly under the south pole. (Though
Hawaii and Japan will get a decent look at it on the way in, and
South America will see it until sunrise.)
Stay tuned for any further events....although we might hope for an observable impact, we will hope that it will be small and ineffective!