2010 TW54 is the first of 4 small asteroids to buzz the Earth in the past week. I should rephrase that last sentence and say it is the first of 4 small asteroids that we know buzzed the Earth last week. For every small one we see, many hundreds pass by unseen. Luckily they are all too small to do anything more than cause a nice fireball light show and drop a few meteorites. Back to TW54, it passed within 0.0011 AU (102,000 miles / 163,000 km / 0.42 lunar distances) of Earth on October 9. At that time it had brightened to 14th magnitude though it would not be discovered for another 2 days.
2010 TN55 got up to 16th magnitude during its close approach to Earth on October 11. At its closest, this 7 to 24 meter across asteroid passed 0.0022 AU from Earth (or 205,000 miles / 327,000 km / 0.85 lunar distances). Having been found by Spacewatch , this is the only one of the 4 recent close approachers not found by the Mount Lemmon Survey
2010 UE flew past the Earth on October 16 at a close distance of 0.00073 AU. That works out to only 68,000 miles or 109,000 km or 0.28 lunar distances. Like most close calls this object is very small (2 to 7 meters across) and would never have survived passage through Earth’s atmosphere to reach the ground as anything more than a bunch of small meteorites.
2010 UJ is a yet another small asteroid (size between 10 and 40 meters across). Residing on an orbit that is not too different from Earth’s, this asteroid may make a good target for future manned and/or unmanned spacecraft missions. That is unless it gets lost which is common for such a small object that can not be observed except when very close to Earth. UJ will pass within 0.04 AU of Earth on Nov. 1 when it will shine at a faint magnitude of 19.9.
2010 UK passed 0.0056 AU (520,000 miles / 830,000 km / 2.2 lunar distances) from Earth on October 16. UK is between 10 and 30 meters across.
Three new Jupiter-family comets were found including the first comet discovered by the PANSTARRS survey. The other 2 were found by Catalina/Mount Lemmon observers Andrea Boattini and Rik Hill. This is Andrea’s 4th comet discovery of the year and 15th overall. For Rik, this is also his 4th of the year and 23rd overall.
P/2010 T2 (PANSTARRS) is a faint comet at ~20th magnitude. Even at perihelion next summer at a distant 3.73 AU it will only brighten to magnitude 19.5. This comet is a short-period Jupiter-family comet with a period of 13.2 years.
P/2010 U1 (Boattini) is a few months past perihelion. Right now it is at its brightest which is still a very faint 19th magnitude. With perihelion at 4.88 AU, this comet only comes a little closer than the orbit of Jupiter. This comet does not travel as far from the Sun as Saturn and its motion is dominated by Jupiter. Hence this is another short-period Jupiter-family comet. It orbits the Sun once every 17.2 years.
P/2010 U2 (Hill) is also a short-period Jupiter-family comet with a period of 8.88 years. Perihelion occurs next month at a distance of 2.56 AU. Its current brightness of 18th magnitude is as bright as this comet will get.
Asteroid Type Mag MOID a e i H Discoverer MPEC 2010 UK Aten 16 0.002 0.87 0.21 4.9 26.8 Mount Lemmon 2010-U17 2010 UJ Aten 20 0.003 0.94 0.09 0.4 26.2 Mount Lemmon 2010-U16 2010 UH Apollo 20 0.003 1.36 0.31 0.7 27.1 Mount Lemmon 2010-U15 2010 UG Apollo 20 0.038 1.51 0.34 8.0 25.4 Mount Lemmon 2010-U14 2010 UE Apollo 19 0.0003 2.63 0.71 3.1 29.6 Mount Lemmon 2010-U12 2010 UD Apollo 15 0.014 1.10 0.26 26.3 21.3 Mount Lemmon 2010-U11 2010 UC Aten 17 0.007 0.94 0.07 4.7 27.4 Catalina 2010-U10 2010 UB Apollo 19 0.010 2.06 0.52 3.4 24.3 LINEAR 2010-U08 2010 UN167 Apollo 21 0.009 1.70 0.59 5.4 27.1 Mount Lemmon 2010-U06 2010 TM167 Apollo 21 0.085 1.16 0.48 5.1 20.9 Mount Lemmon 2010-U05 2010 TL167 Aten 21 0.114 0.97 0.64 12.5 22.4 Mount Lemmon 2010-U04 2010 TK167 Apollo 19 0.065 3.20 0.69 18.6 22.8 LINEAR 2010-U03 2010 TJ167 Amor 20 0.259 2.22 0.44 4.7 21.1 Mount Lemmon 2010-U02 2010 TS149 Apollo 20 0.027 1.50 0.39 3.4 19.8 Mount Lemmon 2010-118 2010 TS55 Amor 21 0.145 1.15 0.46 6.0 24.2 Mount Lemmon 2010-T117 2010 TR55 Amor 18 0.234 2.61 0.53 21.8 18.7 Catalina 2010-T116 2010 TP55 Apollo 21 0.002 2.06 0.62 3.1 20.4 PANSTARRS 2010-T115 2010 TO55 Apollo 17 0.006 1.68 0.41 4.8 26.5 Catalina 2010-T113 2010 TN55 Apollo 20 0.002 2.15 0.77 0.4 27.1 Spacewatch 2010-T112 2010 TL55 Apollo 21 0.120 2.45 0.64 29.6 19.0 Spacewatch 2010-T111 2010 TK55 Apollo 19 0.058 1.06 0.07 24.0 23.8 LINEAR 2010-T110 2010 TF55 Amor 20 0.118 2.63 0.58 12.9 24.0 Mount Lemmon 2010-T106 2010 TE55 Aten 18 0.002 0.93 0.13 1.9 28.1 Mount Lemmon 2010-T105 2010 TD55 Apollo 19 0.073 1.46 0.36 23.3 23.3 LINEAR 2010-T104 2010 TC55 Amor 18 0.121 2.78 0.61 19.7 19.9 Maticic&Zakrajsek010-T103 2010 TA55 Amor 21 0.194 1.52 0.25 15.5 21.9 PANSTARRS 2010-T102 2010 TZ54 Amor 20 0.304 2.29 0.45 9.5 19.0 Spacewatch 2010-T101 2010 TY54 Amor 19 0.218 2.40 0.50 8.7 21.3 Mount Lemmon 2010-T100 2010 TX54 Apollo 19 0.107 1.45 0.34 27.1 20.9 Catalina 2010-T89 2010 TW54 Apollo 18 0.0013 1.05 0.24 2.7 27.6 Mount Lemmon 2010-T88 2010 TV54 Apollo 20 0.007 1.93 0.62 6.2 25.5 Mount Lemmon 2010-T87 2010 TU54 Amor 21 0.263 1.57 0.33 27.4 21.3 PANSTARRS 2010-T86 2010 TS54 Amor 21 0.130 1.46 0.23 15.3 24.5 Mount Lemmon 2010-T85 2010 TR54 Amor 20 0.072 1.70 0.37 4.4 24.5 Mount Lemmon 2010-T84 2010 RS180 Amor 19 0.110 1.88 0.41 2.9 20.5 La Sagra 2010-T109 Comet Type T q a e i Mag Period MPEC P/2010 U2 (Hill) JFC 2010 11 09 2.55 4.29 0.40 16.9 18 8.88 yrs 2010-U19 P/2010 U1 (Boattini) JFC 2010 05 15 4.88 6.66 0.27 8.2 19 17.2 yrs 2010-U18 P/2010 T2 (PANSTARRS) JFC 2011 07 29 3.73 5.59 0.33 8.1 21 13.2 yrs 2010-U07 Type Aten - Earth crossing with semi-major axis (avg distance from Sun) < 1 AU Apollo - Earth crossing with semi-major axis (avg distance from Sun) > 1 AU Amor - non-Earth crossing with perihelion distance < 1.3 AU JFC - Jupiter family comet HFC - Halley family comet LPC - Long-period comet MBC - Main belt comet ECC - Suspected extinct or dormant (or just unrecognized) comet T - Date of Perihelion MOID - Minimum Orbit Intercept Distance, minimum distance between asteroid and Earth's orbit a - semi-major axis, average distance from Sun in AU (1 AU = 93 million miles) e - eccentricity i - inclination H - absolute magnitude Mag - magnitude at discovery Discoverer - survey or person who discovered the object MPEC - Minor Planet Electronic Circular, the discovery announcement
The Transient Sky - Comets, Asteroids, Meteors 