May 29, 2020

2009 UN3:A (Semi-) Bright Asteroid flyby.

This week, a brief cosmic interloper graces our skies. Tonight, 2009 UN3 will glide silently past Earth, at a distance of 0.03667 Astronomical Units, or about 3,400,000 miles. That equates to roughly 13 times the Earth-Moon distance. Not especially close, as Near Earth Asteroids go; 2009 UN3 isn’t considered a hazard on this pass, but has been classified as a Potentially Hazardous Asteroid, (PHA) or one that warrants watching. What is interesting about this particular asteroid is the fact that it is nearly a kilometer in size, and thus should appear moderately bright. At maximum approach, 2009 UN3 will be approximately +12 in apparent magnitude, bright enough for moderate (8” aperture or larger) scopes. Closest approach occurs at 4:48 Universal Time (UT) on the 9th, at which time the asteroid will be moving in a south to north direction through the constellation  Corvus into Virgo around Right Ascension 12h 23’ 26.0” and southern declination -08° 55’ 30”. Keep in mind, the coordinates mentioned are topocentric; with Near Earth Objects (NEOs), parallax as viewed from along the Earth’s surface comes into play.

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12.01.10: Asteroid 2010 AL30 to Make a Close Pass Wednesday.

An interloper to the Earth-Moon system is paying us a visit tomorrow. Asteroid 2010 AL30 is gliding past us at a distance of 78,000 miles, only a little over three times the distance of the geosynchronous satellites and about one –third the Earth-Moon distance, an approach worth noting. First detected by astronomers conducting the LINEAR Near Earth Object survey on Monday, January 11th, 2010 AL30 appears to be a 10-meter class object, and its one year solar orbit raises the possibility that it may be a spent man-made object currently in orbit about the Sun. This has occurred previous, with the recovery of J002E3 in 2002, which gave away its Earthly manufacture due to the presence of titanium oxide paint (a highly un-asteroid-like coating!) in its spectral signature. Interestingly, the final stage Apollo boosters that sent men to the Moon were about 18 meters long and about 7 meters in diameter. Some objections have been raised ABOUT this hypothesis, however, because 2010 AL30’s velocity is inconsistent with a man-made object. Goldstone radar intends to monitor AL30 during its pass Wednesday, January 13th 2010. Amateur astronomers with large apertures and/or CCD imaging capability should be able to pick up AL30 as a swift moving, 14th magnitude (think faint) star gliding through the constellations Orion, Taurus, and Pisces. Chalk up another miss in the Near Earth Object category!