Get your Christmas started with a celestial achievement by tracking down the inner planet Mercury early in the morning.
Because of its tight orbit, Mercury never appears far from the sun. This makes it a challenging object to observe because it never appears in a fully dark sky, only close to the horizon during twilight.
The times when it is farthest from the sun are known as greatest elongations, and this week it reaches greatest western elongation, which means that it will be visible in the morning sky. The chart shows the view looking south-east from London at 07:00 GMT on 25 December, although the view all week is similar, with Mercury more or less holding its position for the remainder of the month before beginning its dive back into the sun’s glare in January.
To stand a chance of seeing this elusive little planet this week, skywatchers will need a clear horizon, as it will have reached only 17 degrees above the horizon when sunrise occurs.
Mercury will also be visible from the southern hemisphere. From Cape Town, South Africa, and Sydney, Australia, the best possibilities for a sighting occur between 04:30 and 05:15 local time on 25 December.
