Fra Mauro

Fra Mauro is a quintessential example of a walled plain. Measuring 96km in diameter and 800m in depth, its ancient form can be located east of 300km Mare Cognitum, the sea that has become known’.

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Type: Crater

Size: 96km

Longitude/Latitude: 17° W, 6.1°S Age: Older than 3.9 billion years

Best time to see: One day after first quarter 1 March) or last quarter (13-14 February)

Minimum equipment: 50mm refractor

It is not the clearest of lunar craters, its ringed plain defined by a gently raised rim to the west, appearing broken in form to the east. It forms a characteristic trio with 60km Bonpland and 48km Parry to the south. This pair are ancient too, but presumably younger than Fra Mauro as their rims appear to bulge into Fra Mauro's boundary, inverting the curve of the walled plain's rim. This suggests they were formed after Fra Mauro and overlay its edge.