[meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter)
From: Bob Loeffler <bobl_at_meteoritecentral.com>
Date: Sat, 17 Jan 2009 17:32:45 -0700 Message-ID: <20090118003233.2C6271053C_at_mailwash5.pair.com> Hi all, Does anyone have coordinates (or better yet, a star chart image) of where this asteroid is located? Thanks, Bob -----Original Message----- From: meteorite-list-bounces at meteoritecentral.com [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of mexicodoug at aim.com Sent: Friday, January 16, 2009 3:58 PM To: Meteorite-list at meteoritecentral.com Subject: [meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter) Dear List, Drat's, I was completely rained out and will be again tonight, and then it head a little too "north" for me. Did anyone see this potential hammer asteroid inchworming from Ursa Major past Arcturus and towards Corona Borealis (actually it is thought to be a non-carbonaceous stony asteroid)? There is still plenty of time for the next two or three days to see it as it fades to Pluto brightness from its current status a being visible through big binoculars or amateur scopes. The actual closest approach is on January 17 at a couple minutes past 17:00 London time. There is no chance this asteroid will hit Earth anytime soon, but is a good illustration of what is being done to track potentially Earth-threatening objects. Both the Puerto Rico's Arecibo ( http://www.naic.edu/public/the_telescope.htm ) and the Mojave Goldstone dishes ( http://www.jpl.nasa.gov/images/dsn/goldstone/ ) Gigantic Radio telescopes, on the NASA/NSF/UStaxpayer payroll, are dedicating serious time to it to figure out its shape, and whatever else they can glean, which while an academic question in this century, could help with strategies to deflect it if necessary at a time in the far future...Typically I think up to ten asteroids monthly (all PHA's, potentially hazardous) are within range and under RADAR study at these installations. It is also a Grrrrreat time to do some spectroscopy on the relatively intense light detectable from Earth during this pass. Basically, taking spectra of the reflected light and analyzing which colors/wavelengths are strongest to get a handle on the composition. Can't wait to find out what new is learned. Hopefully Arecibo stays afloat...:-) Here are the scheduling pages to see the crunching going on for over a week of observations (as we speak errr...breathe) to see what is being done about this object that will pass 11.31 LDs (Lunar Distances) from Earth: http://echo.jpl.nasa.gov/asteroids/1998CS1/1998CS1_planning.html Regarding the distance and its associated dangers - Here is an illustration of ONE Lunar Distance: http://tinyurl.com/9vyyty This is a rather big one and events concerning asteroids this size and proximity happen at best a a few times a year in a fun year. A couple of clarifying comments, the info on this web page indicates the Japanese were the ones who discovered it first, at this place, http://www.kumakogen.jp/culture/astro/astro_e.html Well the Japanese data is two days after the Chinese data so I don't know what's the problem with the crediting of the discovery. Second it mentions that the asteroid measures 0.9 km in diameter plus/minus a FACTOR OF TWO. That puts it between 0.5 and 1.8 km in diameter - so it is very likely to be over 1 km in diameter the catastrophic arbitrary threshold many talk about. Best wishes and Great Health, Doug -----Original Message- ---- From: mexicodoug at aim.com To: Meteorite-list at meteoritecentral.com Sent: Wed, 14 Jan 2009 5:10 pm Subject: Asteroid 136849 approaching (over 1 km in diameter) Dear Listees,? ? Thought I'd pass along to anyone interested in seeing a typical Hammer of God asteroid (no, it is not called Kali, but it really does have a devil of an orbital period: 666 days), in the form of Chinese discovered potentially threatening asteroid (136849) 1998 CS1 (That's CS1, not CSI :)). This asteroid is likely well over 1 kilometer in diameter and will be paying us a quite "close" visit on January 17 at about 5:00PM London time, when it will be about 4.35 million kilometers away (2.7 million miles) from Earth. That's about 11 Lunar Distances (11 times the distance from the Earth to the Moon).? ? For comparison, 4179 Toutatis, which made for a great deal of drama on 29 Sep 2004, is about twice the diameter of 136849 1998 CS1 and passed by Earth at 4 LD's. It was supposedly 10th magnitude, 5 times brighter, but was not as optimally placed to see for many of us.? ? Due to 136849's phase, it will actually be brightest tomorrow night (sometime between 10 PM and 12:30 AM) or whenever is just before Moonrise if you are in the northern hemisphere north of at least 15 degrees latitude or so. If you are South of that you need to put up with the fairly bright Moon but can try to look at it starti ng a couple of hours after Moonrise 'til dawn.? ? I think I'll give it a shot if conditions are ok, since it would be nice to see something this big, this close - about? the same level of difficulty as Toutatis was. For me timing critical as it will barely rise 15 degrees above the horizon when the Gibbous Moonriserises a little before midnight local time. But if you are a Hamburger (Germany) or Juneauean (Alaska), you can observe for at least two hours before Moonrise preferably in thermal knickers...? ? The predicted visual magnitude will be 12.25, well within the range of amateur telescopes. It will be moving against the starry background at about 40 arcseconds per minute which is a third more that the diameter of Jupiter, for comparison, and a very comfortable speed for observation. It's roughly between the Big Dipper of Ursa Major (the Plough) and Leo.? ? For statical thoughts, anything coming within 11.31 LD's of Earth is ROUGHLY about one half-millionth a 'chance' to hit Earth by just looking at cross sectional area, and Earth occupies about one three hundred and twenty millionth of the volume of the sphere centered on Earth with a radius of 11.31 LD. And to think a LD (Lunar Distance) makes it seem so familiar and close! In 2080, it will pass by at 9.4 LD's if all goes according to plan...after a few close ones with Venus, too...? ? BTW today, the=2 0STARDUST spacecraft just passed Earth a couple of hours ago at 0.023 LD's, I think!? ? Here's the orbit of 136849:? http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136849;orb=1? ? Here?re the discoverers:? http://ww? w.bao.ac.cn/bao/station/xl/index-e.html? ? Best wishes and Great Health,? Doug? ? ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-listReceived on Sat 17 Jan 2009 07:32:45 PM PST |
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