Asteroid 20 Massalia at opposition
2013 Nov 1
Asteroid 20 Massalia will be well placed for observation, lying in the constellation Aries, well above the horizon for much of the night.
Regardless of your location on the Earth, Massalia will reach its highest point in the sky at around midnight local time.
This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition, the exact moment of which will be 01:09 UTC. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.
At around the same time that Massalia passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when Massalia lies opposite to the Sun in the night sky, the Solar System is lined up so that Massalia, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as Massalia.
On this occasion, Massalia will pass within 1.232 AU of us, reaching a peak brightness of magnitude 8.7. Nonetheless, even at its brightest, Massalia is a faint object beyond the reach of the naked eye or binoculars; a telescope of moderate aperture and a good star chart are needed.