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Ephemeris: 07/27/2023 – See the Moon’s Bay of Rainbows at sunrise
This is Bob Moler with Ephemeris for Thursday, July 27th. Today the Sun will be up for 14 hours and 51 minutes, setting at 9:14, and it will rise tomorrow at 6:24. The Moon, 2 days past first quarter, will set at 1:38 tomorrow morning.
The moon tonight is a waxing gibbous phase, so it’s more than half illuminated by the Sun. The line between light and dark on the left side of the Moon is called the terminator, which before full is the sunrise line. It is where we can see the greatest detail because the Sun is low in the Moon’s sky there, and creates the longest shadows. Compare it to the right side of the Moon which is seen at nearly solar noon where no shadows are seen, so it has a very bland appearance. One of the cool features of the gibbous moon tonight is Sinus Iridium, the Bay of Rainbows, which is on the upper left part of the terminator. Part of the mountain range that partially rings it is seen in sunlight, while that floor of the bay is still in shadow.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
05/30/2023 – Ephemeris – The Terminator… No, not Arnold Swartzenegger
This is Ephemeris for Tuesday, May 30th. Today the Sun will be up for 15 hours and 17 minutes, setting at 9:19, and it will rise tomorrow at 6:01. The Moon, 3 days past first quarter, will set at 3:59 tomorrow morning.
The Moon tonight is getting to be a fatter and fatter gibbous phase, until Saturday, when it will be full. The Moon will be blindingly bright in telescopes of low magnification. As always the case with the Moon, the most detail is seen near the terminator. The terminator, in the case of the waxing moon, is the sunrise line. After full moon, the terminator becomes the sunset line. This is where the shadows are longest, showing the detail of the craters. Farther from the terminator, where the Sun is higher in the Moon’s sky, shadows are short or nonexistent. Giving the surface a flat appearance. Even lacking wind and water, there is still erosion on the Moon, coming from meteoroid and asteroid impacts and their ejecta. And the breakdown of rocks due to the extreme day-night temperature swings.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
02/06/2014 – Ephemeris – The moon tonight and libration
Ephemeris for Thursday, February 6th. The sun will rise at 7:55. It’ll be up for 10 hours and 3 minutes, setting at 5:58. The Moon, at first quarter today, will set at 2:11 tomorrow morning.
The Moon, being at first quarter today, has the terminator or sunrise line cut the Moon in half tonight. In binoculars and telescopes the best detail is seen near the terminator where the shadows are longest. The farther one wanders with a telescope the flatter the terrain appears. There’s another effect that can be seen. It’s called libration where the Moon appears to slowly wobble during the month. This is mostly caused by the Moon’s very steady rotation countered by the fact that the Moon’s orbit is elliptical and gets ahead or behind the rotation. At the upper right of the Moon is the small Sea of Crises. That has rotated forward a bit revealing yet another sea at the edge of the Moon, Mare Marginis, the Margin or Border Sea.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon highlighting the Ephemeris topics at 9 p.m. on February 6, 2014. Created using Virtual Moon Atlas.
The Moon highlighting the Ephemeris topics at 9 p.m. on February 6, 2014. Created using Virtual Moon Atlas.
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