Starwatch: follow the moon to the Winter Hexagon

The moon will guide you to a fun asterism this week called the Winter Hexagon. Asterisms are patterns made by connecting stars, whereas constellations are the areas of the sky that contain the asterisms.

Not all asterisms belong to a single constellation, however. This week’s pattern joins seven stars from six different constellations. The chart shows the view from London, looking south at 22.00GMT on 25 January.

The almost full moon will be cruising through the middle of the grouping. More than 90% of the moon’s nearside will be illuminated, with just a tiny flattening visible from the unilluminated western hemisphere. To trace the Winter Hexagon, start with the familiar constellation of Orion, and move from Rigel to Aldebarran in Taurus. Then trace around the shape in an anticlockwise direction from Capella to Castor and Pollux to Procyon to Sirius, until you reach Rigel again.

Notice how much sky you have ranged across, putting even the large constellations of Orion, Gemini and Taurus into perspective. From Sydney, Australia, the same view is visible, but in the northern sky, and apparently upside down.