Vesta the brightest asteroid reaches opposition this year in Taurus on December 9th. The asteroid is easy to locate as it is currently positioned close to Jupiter and first magnitude orange/red star Aldebaran, the brightest star in the constellation. This month Jupiter also reaches opposition and at magnitude -2.8, the giant planet dazzles and dominates the night sky.

Vesta can on occasions reach 5th magnitude and therefore naked eye visibility, but this time it does not attain such brightness. On December 9th, the asteroid peaks at magnitude 6.4 and although just below naked eye visibility, it is still a very easy binocular / small telescope target, even from relatively light polluted areas. Since Vesta travels quickly against the "fixed" background stars, its movement can be tracked even on a nightly basis.

Discovery

Vesta was the fourth asteroid to be discovered on the 29th March 1807 by the German astronomer Heinrich Wilhelm Olbers. Along with the other asteroids known at the time (Ceres, Pallas and Juno), Vesta was initially classified as a planet in its own right and subsequently was given its own planetary symbol. With further discoveries, all in the region between Mars and Jupiter, the general term asteroids was coined to describe them. Much later in 2006, the International Astronomical Union (IAU) defined a new classification of dwarf planet of which the largest asteroid Ceres is now a member.

Magnitude

Despite being only the third largest body in the main asteroid belt with a diameter of 530km (330 miles), Vesta is the brightest asteroid. It appears brighter than even the much larger dwarf planet Ceres and the slightly larger asteroid Pallas. This is because its approaches closer to the Earth than the other two and also has a much higher reflective surface. At favourable oppositions, the maximum visual magnitude of Vesta is 5.1 and therefore easily within naked eye visibility, especially from a dark site.

At opposition this year, Vesta will peak at magnitude 6.4.

Location

The beautiful zodiac constellation of Taurus is where to find Vesta in December. The famous constellation represents the head and shoulders of a bull, depicted as charging at neighbouring Orion. Aldebaran denotes the magnificent red eye of the bull with Vesta located only a few degrees to the east. Surrounding Aldebaran is the famous Hyades open cluster and located about 20 degrees to the northwest of Vesta is the most famous open cluster in the sky, The Pleiades (M45). Unmistakable Jupiter is a few degrees north and west of Vesta.

Ceres, Vesta and Jupiter during late November and December 2012 - pdf format

Detailed chart showing Vesta during late November and December 2012 - pdf format

Vesta Data Table