Every year amateur astronomers and sky-watchers look forward to the Perseid meteor shower, which reaches its peak mid-August. For the past few years the sky has been lovely and dark for the shower, but this year a very bright Moon will be shining close to the part of the sky the meteors come from, which will greatly reduce the number we will see. However, the Moon itself will be a fascinating sight, so this month our Moon Tour doesn’t just have a single destination. Instead we’re going on a sightseeing cruise around the most striking features visible on the Moon after it rises around midnight on 12 August, the date of the peak.
Once the Moon is clear of the horizon you’ll see that the illuminated half is light in some places and dark in others. The light areas are the so-called lunar highlands. These are rugged, mountainous areas, dominated by jagged peaks and the deep valleys between them. They are made of very old lunar rock, and appear so bright to us here on Earth because they reflect a lot of sunlight. In contrast the dark areas are flat, low and reflect much less sunlight. These dark areas are the famous ‘seas’, or mare, and they are actually vast plains of ancient, frozen lava.