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Posts Tagged ‘Earthshine’

10/27/2022 – Ephemeris – Trying to spot the young Moon tonight

October 27, 2022 Comments off

This is Bob Moler with Ephemeris for Thursday, October 27th. Today the Sun will be up for 10 hours and 24 minutes, setting at 6:38, and it will rise tomorrow at 8:15. The Moon, 2 days past new, will set at 7:55 this evening.

The Moon is again making its appearance in the evening sky as a thin crescent. The crescent appearance is because the moon is mostly between the Earth and the Sun. So we are seeing mostly its night side, with just a sliver of it being sunlit. But the Moon has the Earth in its sky, which is quite big and bright, much brighter than the Moon in our skies. And when the Moon’s phase is thin, the Earth, having the opposite phase, will be a nearly full gibbous orb. The Earth illuminates the Moon’s night side with earthlight. We call it earthshine, when the whole Moon appears faintly inside the crescent. It’s also known more poetically as the “Old moon in the new moon’s arms.” If you’re not sure, because the effect is faint, check it out in binoculars. The effect should last another night.

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

Earthshine by Bob Moler

An old picture of mine overexposing the crescent Moon to bring out earthshine. The moon was a wider crescent than it will appear to be tonight.

06/07/2016 – Ephemeris – The Moon reappears in the evening sky

June 7, 2016 Comments off

Ephemeris for Tuesday, June 7th.  Today the Sun will be up for 15 hours and 28 minutes, setting at 9:26, and it will rise tomorrow at 5:57.  The Moon, 3 days past new, will set at 11:41 this evening.

The  Moon tonight is a thin crescent with the night side faintly illuminated by the Earth.  The effect is called earthshine.   The small dark sea of Crises, or Mare Crisium, near the right edge of the moon will be cut in half by the moon’s terminator, its sunrise line.  Venus, which passed behind the Sun yesterday, though now an official evening planet probably won’t become easily visible till near the end of summer.  The evening sky now through mid July is a time where it seems that twilight never ends.  However for almost the next two weeks, we have the bright planets Jupiter, Mars and Saturn plus the Moon to help us forget the seemingly forever twilight blues.  After that we’ll have just the planets. Not a bad deal.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Moon showing earthshine

The Moon showing earthshine at 10:30 p.m. June 7, 2016. Created using Virtual Moon Atlas.

Note:  The image, from Virtual Moon Atlas, has been rotated to show the approximate appearance in the sky of the Moon low in the southwest.  I didn’t attempt to add the sky brightness and color.

05/19/2015 – Ephemeris – The crescent Moon reappears in the west

May 19, 2015 Comments off

Ephemeris for Tuesday, May 19th.  Today the Sun will be up for 14 hours and 57 minutes, setting at 9:08.   The Moon, 1 day past new, will set at 10:42 this evening, and tomorrow the Sun will rise at 6:09.

The Moon is again making its appearance in the evening sky as a thin crescent.  The crescent appearance is because the moon is mostly between the Earth and the Sun. , so we are looking at just a sliver of it is sunlit, and most is unlit by the sun.  But the Moon has the Earth in its sky, which is quite bright, and when the moon’s phase is thin, the Earth illuminates its night side with Earth light.  We call it Earthshine, when the whole Moon appears faintly inside the crescent.  It’s also known more poetically as the “Old moon in the new moon’s arms.”  The planets Venus and Mercury also exhibit crescent phases because they can be positioned between the Earth and the Sun, as Mercury is now and Venus will be next month.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Planetary grouping

Close grouping of, from right to left, Venus, Jupiter, Venus and the overexposed crescent Moon showing Earthshine on June 15, 1991. Credit: Bob Moler.

03/07/11 – Ephemeris – Earthshine

March 7, 2011 Comments off

Monday, March 7th.  The sun will rise at 7:09.  It’ll be up for 11 hours and 28 minutes, setting at 6:37.   The moon, 3 days past new, will set at 9:49 this evening.

The moon tonight will appear as a thin sliver, with not much visible on the thin illuminated portion.  However if as you look at the moon tonight you have the funny feeling that the whole moon is visible, you are right.  It’s easily confirmed with a pair of binoculars or a small telescope.  What is illuminating the dark part of the moon is earthshine.  The earth is big and bright in the moon’s sky, and nearly full from its vantage point.  The effect used to be called by the term “Old moon in the new moon’s arms”.  The effect was first explained by Leonardo DaVinci some 500 years ago.  The effect will disappear in a few days as the moon gets brighter and the earth less so in the moon’s sky.  Earthshine will appear again when the moon appears as a waning crescent in the morning.

* Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Update:

Earthshine is notoriously hard to photograph.  Here’s one of mine from 1991.  Part of a planetary conjunction picture with a short focal length telephoto lens.  I’ve cropped out the planets.  The sunlit side of the moon is vastly overexposed causing the blooming in the photograph.

Earthshine by Bob Moler

Earthshine on the crescent moon