Comets and Asteroids
26 Proserpina.
Asteroid 26 Proserpina is one of the 1.1-1.9 million bodies within the asteroid belt larger than 1km across – and with a diameter of 94x90km, it’s at the upper end of the asteroid size spectrum. It was discovered in May 1853 by the German astronomer Robert Luther,
his second asteroid discovery. It orbits the Sun at an average distance of 397.4 million km, taking 1,581.2 days to complete each trip. After a number of discrepancies in the reported rotation period, it’s now known that 26 Proserpina spins once every 13.11 hours. This is a typical S-type asteroid, a name given to silicaceous asteroids that have a stony composition.
During March, 26 Proserpina is an 11thmagnitude object in Leo and requires a telescope to see. It dims from mag. +11.0 on 1 March to +11.6 by the end of the month, but ironically should be easier to spot when it is dimmer thanks to its proximity to mag. +3.5, Eta (d) Leonis. On 1 March, Proserpina is 1.2º to the northeast of mag. +6.2, 42 Leonis. The asteroid then tracks in a gentle west-northwest curve towards Eta Leonis, passing 30 arcseconds south of the star (as seen from the centre of the UK) at 21:00 UT on 24 March. As ever, the best way to identify whether you’ve actually seen 26 Proserpina is to photograph or sketch the stars in the suspected field of view. Compare similar results from subsequent nights and the asteroid should make itself known because of its movement.
The asteroid is named after the ancient goddess Proserpina, the daughter of Ceres and Jupiter in Roman mythology. Her Greek counterpart is the goddess Persephone, who also has an asteroid named after her, 49km 399 Persephone.