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]
References
- ↑ Rice, Tony. "X marks the moon on Thursday night". WRAL.
- 1 2 Harrington, Philip S. (2010). Cosmic challenge : the ultimate observing list for amateurs. Cambridge: Cambridge University Press. p. 1999. ISBN 978-0-521-89936-9.
- ↑ Chapman, David M.F. "The Lunar X Files: a fleeting vision near the crater Werner" (PDF). Willingboro Astronomical Society.
External links
- 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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