"Walking on the Moon" with the VLT

A small area of the lunar surface, on the rim of the 56-km crater Taruntius . This formation is located some 6° North of the lunar equator and near the intersection of Mare Tranquillitatis and Mare Foecunditatis in the Eastern hemisphere. It is late in the lunar "day" and the Sun is low above the western horizon. The long shadows greatly enhance the visibility of shallow surface formations. The largest crater in the field (at the top) is named Cameron and measures about 10 km across [1]. This photo (in near-infrared light at wavelength 2.3 µm) was obtained in the morning of April 30, 2002, with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory. The on-line AO image corrections were achieved by guiding on an illuminated lunar peak, just outside the field shown. This image is "raw", i.e. it has only been subjected to "background subtraction" and cosmetic removal of a few "bad" pixels. Some of the slopes in direct sunlight are overexposed. With angular resolution of about 0.07 arcsec - corresponding to 130 metres at the distance of the Moon - it is undoubtedly one of the sharpest images of the lunar surface ever obtained with a ground-based telescope . In this reproduction, the North direction is about 10° to the left of the top, with West to the left. The size of the field is about 25 x 25 arcsec 2 ; when taking into account the viewing angle, this corresponds to approximately 60 x 45 km 2. The pixel size is that recorded by NACO, 0.027 arcsec, or approx. 50 metres on the Moon.