Starwatch: Mercury offers rare viewing chance for early risers

Elusive planet will make a pre-dawn appearance as it seems to stray from the sun

We start December with one of the best chances to see Mercury this year, at least for the northern hemisphere. The elusive inner planet never strays far from the sun but this week it reaches the configuration known as the greatest western elongation.

This means that from our vantage point on Earth, the planet appears as far away as possible from the sun. It will appear in the pre-dawn twilight sky. For observers at mid-northern latitudes, the geometry is favourable, and so the best views are possible 30 to 60 minutes before sunrise.