Essay On Lunar Sunrise

explanatory Essay
880 words
880 words

Lunar sunrise and sunset rays are a rare phenomenon which occurs when shafts of sunlight shine through gaps in crater walls and mountains to cast a spike of light across a dark crater floor. They happen infrequently and only during sunrise and sunset when there is a very low angle of sunlight. The rays can range from thin slivers of light to triangular patches of illumination. They differ from lunar rays where debris from impact craters is strewn across the face of the Moon.
A true lunar light ray has been defined as one which crosses 3 degrees of longitude while being less, on average, than ¼ degree in latitude width. They can occur at either sunrise or sunset. Because of the geometry involved they are usually short-lived and occur within only a 2 to 3 hour window of opportunity.
Although lunar light rays were first observed over 150 years ago, they have gained in popularity only recently after a report of them was published in an astronomy journal. Since then amateur astronomers have discovered several craters where sunrise or sunset rays have shone through a crumpled or broken crater wall and created these light shows which lasted only a few hours.
Lunar light rays can be detected by scanning along the lunar terminator, and if you’re lucky, you just might spot one. For those who prefer not to leave it to chance, the website “CalSKY” can calculate sunrise and sunset times along with the sun angle to determine which lunar craters will display light rays and when. After inputting your geographical coordinates, you need to enter the date, time and duration you wish to observe. CalSKY will then generate a list of craters exhibiting rays, including date and time of visibility together with a map showing the crater and observer r...

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...nning out, and extending to the western wall.
Vogel Ray
A sunrise ray crosses the floor of Vogel, starting as a thin triangle of light that progressively thickens.
Walter Ray

The Walter ray is a fairly dramatic shaft of light that crosses the floor of Walter at sunset. A spreading wedge of light is cast across the floor by a gap in the wall. A small crater near the gap looking like a tiny crown cast three pointed shadows across the floor towards the central peak.
A complete list of craters with lunar sunset and sunrise rays can be obtained from the website of the Robinson Lunar Observatory at
Although not of any scientific value, the rarity of these events, coupled with the short time frame they are visible, make these real challenges for the avid lunar observer. So if the sky is clear, go catch some rays!

In this essay, the author

  • Describes the ray as a moderately broad pie-shaped swath of light that illuminates babbage's crater floor.
  • Explains that the high plains of northern bonpland are crossed by a thin ray from the western rim of parry just short of 8 degrees south.
  • Explains that the ray extends across the plains to the west of burnham, rather than across its floor.
  • Describes how light shines through a crack in the western wall at sunrise, causing an illumination patch to cross the crater floor and eastern rim.
  • Explains that sunrise and sunset rays have jumped-started the surge in interest in recent years. the wall between these craters has a deep cleft.
  • Explains that the double ray is formed by a cleft in hypatia's eastern wall, which creates an arc shining across its floor.
  • Analyzes the light emanating through a broken segmented area of the western rim.
  • Describes how a very narrow shaft of light spreads out in width from slightly west of the central peak to the floor of crater.
  • Describes how a ray of light projects from the eastern wall to the central peak of the crater at sunset.
  • Explains that a very small triangle of light shines on the western crater rim just south of
  • Explains that a thin shaft of light crosses orontius' floor, along the north rim of the crater.
  • Describes how three shafts of illumination extend across the floor of ptolemaeus, which otherwise remains in darkness. these rays illuminate the gently undulating terrain of the cayley formation.
  • Explains that a short, very thin shaft of light originates north and west of crater c and extends to the western wall.
  • Analyzes how a sunrise ray crosses the floor of vogel, starting as thin triangle of light that gradually thickens.
  • Explains that lunar sunrise and sunset rays are a rare phenomenon that occurs when shafts of sunlight shine through gaps in crater walls and mountains.
  • Explains that the halley ray occurs at sunrise and sends a spike of light across the crater floor.
  • Explains that the walter ray is a dramatic shaft of light that crosses the floor of walter at sunset.
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