Saturday, 22 May 2010

Rupes recta (Straight Fault)

These two show a bit of the moon on two different nights.  The long straight shadow is caused by a fault (or split)  in the surface of the Moon where one side has dropped relative to the other.  The top picture is only a quick sketch done on April 22, the second is a proper drawing done last night – May 21st.

Both 120mm refractor x200.
Rupes Recta A
The difference in the shadow cast by the fault is very different in the two pictures, although the difference in the Moon’s age (ie the time from the last New Moon) is 8.2 days and 7.8 days respectively.  The fault is around 67 miles long and between 300 and 900 feet high.  It is not a vertical drop!  and has a shallow slope – you could probably walk up it! Rupes Recta B

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