2021, June 13: Moon Passes Mars

June 13, 2021:  After sunset, look for the thin crescent moon near Mars.  The lunar sliver is also to the upper left of the star Pollux.

2021, June 13: The crescent moon is above Mars.
Chart Caption – 2021, June 13: The crescent moon is above Mars.

by Jeffrey L. Hunt

Two evenings after the crescent moon appeared with Venus, the lunar slice appears 2.9° above Mars and over 10° to the upper left of Pollux.

Step outside about 45 minutes after sunset and look to the west-northwest for the crescent. Follow the pair until they set over 2.5 hours after sunset and 15 minutes after the end of evening twilight.

The planet and the moon appear in the same binocular field.  Notice the gentle illumination on the moon’s night portion.  This is earthshine, from sunlight reflected from Earth’s oceans, land, and clouds. This evening from the moon, Earth is a bright gibbous phase. The same occurs when a bright moon illuminates the terrestrial landscape.

If the observations are made early in the evening, brilliant Venus is about 20° to the lower right of the lunar crescent.  The planet is easily observed through the delicate, colorful hues of early evening.

Moon and Venus, 2020
The crescent moon appears near Venus as the brilliant planet approaches the star Elnath.

Photograph the moon and capture earthshine with a tripod-mounted camera.  Exposures can range up to a few seconds.  On the photo above the moon was photographed with a 140mm lens at f/5.6.  The exposure was 4 seconds with an ISO set at 100.  The waning crescent moon was 14% illuminated, similar to the phase this evening.

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