Lunar X

Lunar X formation taken January 30, 2012, the formation is off the center towards the right

The Lunar X (also known as the Werner X) is a clair-obscur effect in which light and shadow creates the appearance of a letter 'X' on the rim of the Blanchinus, La Caille and Purbach craters.[1]

The X is visible only for a few hours before the first quarter,[2][3] slightly below the lunar terminator. Near to the X, the Lunar V is also visible, formed by Ukert crater and several other small craters.[2]

Half waxing moon with inset closeup of Lunar X, used by a 60mm refractor telescope

References

  1. ↑ Rice, Tony. "X marks the moon on Thursday night". WRAL.
  2. 1 2 Harrington, Philip S. (2010). Cosmic challenge : the ultimate observing list for amateurs. Cambridge: Cambridge University Press. p. 1999. ISBN 0-521-89936-2.
  3. ↑ Chapman, David M.F. "The Lunar X Files: a fleeting vision near the crater Werner" (PDF). Willingboro Astronomical Society.
  • LPOD articles:
    • Wood, Chuck (August 29, 2004). "X Marks the Spot". Lunar Photo of the Day.
    • Wood, Chuck (December 12, 2013). "X Marks the Spot". Lunar Photo of the Day.
    • Wood, Chuck (March 9, 2014). "Xquisite". Lunar Photo of the Day.
  • APOD articles:
    • Nemiroff, R.; Bonnell, J. (eds.). "Lunar X". Astronomy Picture of the Day. NASA.
    • Nemiroff, Robert; Bonnell, Jerry (December 10, 2016). "The Lunar X". Astronomy Photo of the Day (APOD). - also includes the Lunar V


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