According to the latest calculation with JPL's Horizons ephemeris machine it will be Monday, June 27, at precisely 17:00 UTC ± a few minutes when asteroid 2011 MD - with a diameter of a dozen meters or two, i.e. roughly house-sized - will pass closest to Earth: It will then be only 0.0001247 AU = 18,665 km from the planet's center or about 12,280 km from its surface. As the all-time list of closest approaches shows, this is by no means a record: at least three asteroids that got provisional numbers came even closer - and another one was discovered and then hit us (2008 TC3 of course). Our newest visitor will reach its closest Earth approach point in extreme southern latitudes (in fact over the southern Atlantic Ocean).
The incoming trajectory leg - some helpful animations from different points of view! - passes several thousand kilometers outside the geosynchronous ring of satellites and the outgoing leg passes well inside the ring. One would expect an object of this size - 5 to 20 meters, depending on the albedo - to come this close to Earth about every 6 years on average: a little video shows it moving in the sky this morning. There had been initial speculation that 2011 MD might be old space junk, but this seems practically excluded today. Some coverage here, here (earlier), here and here - and we have already an early contender for the most stupid headline: 5 to 20 meters diameter = "giant asteroid" ... :-)
In other planetary system news we have new data about and a fuzzy pic of centaur Echeclus in outburst, new Afrho data - what that means - from Elenin and an info page about PANSTARRS; there is still some confusion regarding its orbit. • A big bolide in TX & OK on June 20, and yours truly gets quoted re. the Draconids 2011 outlook. • An occultation of a star by Pluto was observed with SOFIA - central flash included - and from the ground, and there will be another one shortly. • A great amateur pic of Mercury showing e.g. the Caloris basin and a montage of Saturn's motion near Porrima.
From the total lunar eclipse 10 days ago report of successful observations with the LRO's DIVINER instrument, another gallery of amateur pictures (more, more and more collections; much more), a German review of what happened, a timelapse video and more selected reports and pictures from the Philippines (more), Nepal (more), India (more and more reports and more, more, more and more pictures), South Africa (a precise lightcurve!), Namibia, Greece (with thunderstorm; alt.; more, Hungary, Ireland, Spain, Austria (unusual timelapse movie; more, more, more, more, more, more, more, more, more, more, more, more and more pics & stories) and Germany (Donauwörth, Garching, Munich, Ulm and Stuttgart), plus a serious and a funny and another weird story on the TLE.
Elsewhere in the Universe a lightbridge in AR 1236 on the Sun where spots were published 400 years ago, a flare & CME on June 20 (video; it was again w/o Earth effects), how Chandra coped with the June 7 flare and yet another (alt.) and another space wx scare story. • The SN 2011dh in M 51 - now at ~12.3 mag. - on June 23 vs. 4 blinking and paired, a June 20 drawing, confusion about the progenitor and how to locate it. • NLCs from Stockholm on June 18 and sky color FX from a Chilean volcano. • An amateur imaging spysats (more). • And another attempt to end leap seconds.