Comets and Asteroids

Minor planet Juno.

Minor planet Juno reaches opposition on 2 July. In June, you can find it passing close to the tail of Aquila, the Eagle, incidentally the same general area we cover in our DeepSky Tour on page 62.

This was the third minor planet discovered after Ceres (now a dwarf planet) and Pallas. It was discovered by German astronomer Karl Ludwig Harding in September 1804 and is now known to be the 11th-largest of this class of body. It is also a main belt asteroid, with an orbital period of 4.36 years. At perihelion it comes within 2.0 AU (299 million km) of the Sun, moving out to 3.3 AU (494 million km) at aphelion.

At 01:00 BST (00:00 UT) on 1 June, Juno can be found roughly mid-way between mag. +3.4 Lambda (h) and mag. +4.0 12 Aquilae. From this location, it slowly moves to the west, passing across the border from Aquila and into Scutum on 10 June. Its westward track has it passing just less than 2º north of the wonderful Wild Duck Cluster, M11, on 18-21 June. At this time it’ll also be about 0.33º north of 9th-magnitude open cluster NGC 6704, and this is a possible photographic opportunity.

On the night of 24 June and into the morning of 25 June, Juno passes 8 arcminutes south of mag. +4.2 Beta (`) Scuti and ends the month 1º south of the mag. +9.2 open cluster Trumpler 35 (Collinder 388).

Juno brightens from mag. +10.2 on the 1st to +9.8 by the 30th. The best way to see it is either through large binoculars or through a small scope. The best way to identify it is to sketch or image the area of sky you believe it to be in, then, repeat the process another night and compare your results. If one of the ‘stars’ appears to move, this is likely to be Juno.