Pallas in 2009

Pallas was at opposition on 4 December 2008 when it reached magnitude 8.0 and was in the constellation Columba. The opposition late in 2008 results in there being no opposition during 2009, but the asteroid has a magnitude 9.5 or brighter throughout the year.

During the opposition period, the highly inclined orbit of Pallas resulted in a path in the form of an elongated retrograde loop which started in Lepus. After moving into Columba, the asteroid moved westward into Caelum in mid December 2008. On January 11, as it turns to move northwards, Pallas crosses into Eridanus. 10 days later Pallas reaches a stationary point in its orbit when the retrograde, westerly, component of its motion is reversed. Combined with its strong northerly movement this will take the asteroid back into Lepus on February 16. The form of the retrograde loop is illustrated in the chart for the period.

For the rest of 2009 the easterly movement of Pallas through the stars is much more conventional. It crosses into Orion on March 16, passing between Rigel, β Orion magnitude 0.3 and κ magnitude 2.1. By this date, Pallas will be setting about an hour after midnight, so will be essentially an evening object.

Over the next few weeks Pallas crosses a corners of Monoeceros and Orion before re-entering Monoceros on April 17 and then into Canis Minor on May 12. While in Canis Minor, the asteroid passes less than 1.5° from Procyon, magnitude 0.4, on May 28. By then it will set about 9.30 pm, so will be at its best for observation once the sky darkens following sunset.

On June 11 Pallas moves on into Hydra, where it will follow an easterly track close to the constellation's border with Leo. It will be 7° from Regulus, α Leo,on August 6, but by then will be getting low to the west by the time the sky darkens following sunset.

Pallas it at conjunction with the Sun on September 13, and will be too close to it for observing for most of the rest of the year. By December 31 it will be about 14° above the eastern horizon in the morning about 50 minutes before sunrise.

Pallas has a diameter of about 532 km virtually the same as Vesta. The orbital period is 4.62 years and the distance of the asteroid from the Sun ranges from 2.14 AU to 3.41 AU.   At its closest possible approach, Pallas is 1.23 AU from the Earth. The asteroid's orbit is highly inclined at 34.8° to the ecliptic with an eccentricity 0.23. The effect of the high inclination was evident in 2009 when at opposition Pallas had a declination nearly 33° south, 55° south of the ecliptic.

As its number implies, Pallas was the second Minor Planet or Asteroid to be discovered.  The discoverer was H W Olbers in 1802 at Bremen.