Orwell Astronomical Society (Ipswich)

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Motion of 3200 Phaethon, 16 December 2017

3200 Phaethon is an Apollo asteroid, with an orbit that brings it closer to the Sun than any other named asteroid, at a perihelion distance of only 21 million km (although numerous unnamed asteroids come closer). It is the parent body of the Geminids meteor shower, which occurs annually in mid-December.

At 23:00 UT on 16 December 2017, Phaethon passed a mere 10,312,040 km from Earth, moving at an apparent velocity of 38 arcsec per minute. It was visible in small telescopes, at brightest shining at magnitude 10.8. It will not make an approach closer to Earth until 2093, when it will pass at a distance of 2,964,000 km.

I captured the following video of the passage, from 21:03-21:56 UT. The slightly wiggly track is an artefact of the autoguider.

Nigel Evans