Kitt Peak Nightly Observing Program
Splendors of the Universe on YOUR Night!
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Hansteen and Billy
These two craters are nearly identical in size, but not in most other ways. Hansteen has terraced walls and a fractured floor, while Billy has a smooth, flooded floor. Though they are near the limb and somewhat foreshortened, they are a good pair to demonstrate contrasting crater features.
Tycho is a prominent crater on the Moon—but it doesn’t stand out because of its size. At 85 km in diameter it is one of thousands of craters on the Moon its size and larger. Tycho stands out because of its rays. Crater rays are formed by ejecta—dust and debris ejected from the surface during and impact event, that spreads upwards and outwards, and eventually settles back down on the surface to leave behind radial spikes around newly formed craters. Prominent and extensive rays suggest that a crater is fresher, or more recently formed. Tycho may be as young as 108 million years old. That may sound old, but craters on the Moon can remain for billions of years.
Also known as a twilight zone, a terminator is where the shadow of night and the light of day come to meet on a planetary body. At the edge of where the Sun’s light reaches, the terminator is constantly moving as the Moon rotates. When observing the Moon, many features are best observed when they are near the terminator, where shadows are long and plentiful. The shadows provide higher contrast between surface features.
Your Telescope Operator and Guide. Thank you for joining me this evening! See you soon!!
The web page for the program in which you just participated is at
Nightly Observing Program. Most of the above images were taken as
the Overnight Telescope Observing Program. For more information on this unique experience please visit Overnight Telescope Observing Program.
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