Images from the NTU telescope

These three adjacent craters on the surface of the Moon are probably the most interesting craters and well visible during half moon. The image was taken on May 21, 2010 with the Meade ETX-125 at NTU.

The craters are called Ptolemaeus (lower), Alphonsus (centre), and Arzachel (upper). Arzachel is the youngest of the three, 97 km in diameter and 1 km deep. The right image has increased brightness and contrast to highlight three interesting darker areas in Alphonsus, pointed out by arrows. Before the Apollo missions, the patches were initially linked to volcanic activity. Now they are thought to be normal craters where the creating meteorites have thrown up darker material below ground level.

Alphonsus has also been linked to transient lunar phenomena that are changes of brightness or colour of certain regions on the Moon. Scientists have observed Radon gas being emitted from this crater that could cause these effects.

Return to the image gallery.