This week the moon makes a close pass of Mars in the constellation Gemini, the twins, in a pleasing meeting of one moon, one planet and two stars.
The chart shows the view looking east-north-east from London at midnight as 23 October becomes 24 October. The moon will be 21.8 days old and will have 53.4% of its visible surface illuminated. This makes it a last quarter moon, slipping from the waning gibbous phase to waning crescent.
Mars will be a distinctive orange-red colour and will be around twice as bright as the star Pollux, which itself is a little brighter than its “twin” Castor. Careful inspection will also reveal a colour variation: Pollux is slightly more orange than the yellow-hued Castor.
Mars is about 160m kilometres from Earth, and brightening rapidly as Earth’s orbit carries us closer towards this near planetary neighbour. By the end of the year, the red planet will be shining brightly indeed, and it will make its closest pass to Earth for the next two years in January 2025.
This week’s conjunction is visible from the southern hemisphere, although only in the early hours of the morning and low in the south-eastern sky.
