MOONWATCH

August's top lunar feature to observe

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Flammarion Type: Walled plain Size: 75km Longitude/latitude: 3.7° W, 3.3° S Age: Older than 3.9 billion years Best time to see: First quarter (1-2, 31 August); six days after full Moon (16 August) Minimum equipment: 50mm telescope

Flammarion is an inconspicuous walled plain near the centre of the Moon's disc. On the Earth-facing side of the lunar surface, there are two great crater 'chains' containing three large craters. On the western side of 350km Mare Nectaris is the roughly north-south chain formed by 101km Theophilus, 98km Cyrillus and 100km Catharina. Further west, lying roughly on the Moon's central meridian at the same general latitude as the Theophilus chain, and running from south to north, are 98km Arzachel, 118km Alphonsus and 154km Ptolemaeus. Immediately north of Ptolemaeus is 41km Herschel. To the north and slightly west of Herschel, lies 75km-diameter Flammarion, appearing like a mini Ptolemaeus.