Every month just after the first quarter phase of the Moon, like it is tonight (Wednesday) is the best time to hunt down in a small telescope one of the most striking features on the lunar surface called the Straight Wall or Rupes Recta. As the name implies, this giant 120 km long lunar fault looks like a straight dark line through the eyepiece.
The view is so dramatic right now because the rising sun is casting a long deep shadow the entire length of this steep cosmic cliff. Current estimates are that the cliff is about a 400 meter sheer drop.
First described by 17th century astronomer Christian Huygens, the straight wall lies in the Mare Nubium and is impressive in any sized telescope you have.
You can have another chance to see the Straight Wall during last quarter Moon when the setting sun illuminates the face of the long cliff, making it appear as a bright, white straight line – equally as dramatic.
You want to know what kind of other cool features you can track down tonight on the Moon? Check out the Hitchhiker’s Guide to the Moon - a very detailed website dedicated to showing you exactly what you can see on the surface of the moon – generated for every day of the calendar.
Posted in Solar System, The Moon | 1 Comment »