Minor planet 15 Eunomia reaches opposition on 13 December 2024, when it can be found shining at mag. +8.1 among the stars of Auriga.
At this brightness, it’s best viewed using a small or medium telescope.
Its monthly track has it starting just east of the Cheshire Cat asterism, a pattern that consists of a smiling mouth and two stars representing the eyes and, if you have a good imagination, a tail too.
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15 Eunomia initially passes between mag. +6.0 M36 and mag. +6.4 M38, heading along a track that takes it over the diffuse nebula IC 417 adjacent to mag. +5.1 Phi (φ) Aurigae.
It scrapes past the southern corner of the Cheshire Cat’s mouth around opposition, thereafter heading southwest along the stars of the cat’s tail.
This is good deep-sky territory too, with the Flaming Star Nebula IC 405 and open cluster NGC 1893 surrounded by more diffuse nebula in the form of IC 410, all in the area that Eunomia passes through mid-month.
The track ends just south of a point one-third of the way along the line from mag. +2.7 Hassaleh (Iota (ι) Aurigae) and Elnath (Beta (β) Tauri).
Eunomia has dimensions of 330 x 245 x 205km and is somewhere between the eighth- and 12th-largest asteroid in the main belt between Mars and Jupiter.
If you manage to spot asteroid 15 Eunomia, let us know by emailing contactus@skyatnightmagazine.com.
This guide appeared in the December 2024 issue of BBC Sky at Night Magazine.
