Following the Moon for Amazing May Astronomy

Moon and Venus

The May moon meets Venus and Mercury at dusk on their way to the solar eclipse and more.

Wonder where all the action of the solar system is hiding? While the twilight sky appears to be devoid of planets (except for Mars), that will change tonight. The catchphrase for astronomy in May 2021 is “Follow the moon” as it makes several spectacular planetary passes and then starts the first solar eclipse season of the year.

First off, the slender, growing crescent moon covers the bright planet Venus tonight, May 12th. Although this happens over the South Pacific and most of us will miss the actual event, the two will nestle very close together on the evening of May 12th, making a very photogenic couple. Ashen light or earth shine on the dark branch of the moon (caused by sunlight reflecting off the earth) gives the scene an overall 3-D appearance.

The sky view at dusk on May 12, looking west. Photo credit: Stellarium.

Venus, with a magnitude of -3.9, will actually be a great guide on the night of May 12th to discover the ethereal, slender crescent moon. Sure, Venus is tiny, 10 inches in diameter, and 98% illuminated, compared to the Moon’s apparent diameter of 29.5 inches and 1.2% illumination. But Venus is inherently brighter and bright enough that you can see it around the largest solar stretch during the day … if you know exactly where in the sky to look for it. Your next chance to try this out in 2021 is on October 29th, when Venus sits 47 degrees east of the Sun and dominates the twilight sky.

The footprint for the occultation of Venus by the moon on May 12th. Credit: Occult 4.1.

Do you see this zero magnitude star over the Venus-Moon couple tonight? This is the innermost planet, Mercury. In fact, Mercury is well on its way to one of its best appearances for observers in the northern hemisphere this month in 2021, reaching 22 degrees east of the Sun on May 17th. After that, Mercury loses altitude night after night as Venus gains importance until the two switches flip on the night of May 29, when the two planets sit in the same telescopic field of view, only 24 ‘apart, less than the diameter of one Full moon.

Follow this moon as it grows and pass 1.5 degrees from +1.6 magnitude Mars on the evening of May 16.

Today’s first sighting of the slender crescent also marks the end of the fasting month of Ramadan for Muslims worldwide and the beginning of the celebration of Eid al-Fitr. The Muslim calendar is based entirely on the lunar cycle, which means that months like Ramadan are 11 days ahead of the solar-based Gregorian calendar. Other hybrid systems – like the Hebrew or Chinese calendars – are based on both solar and lunar cycles and therefore need to add an additional or “embolic” month every 2-3 years to stay in sync.

The moon passed its most distant climax on May 11, 2021 at a distance of 406,511 kilometers (its “furthest point from Earth”). This also prepares us for two interesting astronomical events in the coming weeks:

The first is the total lunar eclipse on May 26th. This will favor the Pacific region with a maximum total duration of 14 minutes and 30 seconds. This also falls near the closest perigee (the “closest point” for the moon to earth) for 2021, just 10 hours earlier, at a distance of 357,309 kilometers. No doubt the ‘Super Blood Moon’ meme is set to sweep the internet once again.

Visibility prospects for the total lunar eclipse on May 26th. NASA / GSFC / F. Espenak.

Then, two weeks later, the moon will be near its peak again and too small to cover the sun during the annular solar eclipse on June 10th. The annulus for this eclipse will extend through northeast Canada northeast across Hudson Bay, although much of northeast North America will experience a fine, ascending partial eclipse at dawn.

The annular solar eclipse of June 10th. NASA / GSFC / AT Sinclair

Can’t you wait until June If you live on the US east coast, another fascinating space event may soar in the sky tonight: watch out for NASA Wallops’ launch of a suborbital Black Brant XII rocket in Virginia with the KiNET-X experiment. The energy and momentum transport experiment on a KiNET scale releases chemical tracers for barium vapors about 10 minutes after starting in order to map and understand the energy transfer in the upper atmosphere. These type of launches are always difficult to get from the pad as the sky is clear not only at the Wallops launch site, but also at the Bermuda tracking station down below to watch the experiment. A similar mission from Wallops took weeks to launch a few years ago. Another, called AZURE, was launched from the Andoya Space Center in the High Scandinavian Arctic in 2019 with similarly eerie results. KiNET-X has a 40 minute startup window tonight starting at 8:06 p.m. EDT / 00:06 UT.

View the prospects for today’s KiNET-X launch. Photo credit: NASA / GSFC

We’ll be tweeting as @Astroguyz about these heavenly heavenly events, launches, and more. Here on Universe Today you can find detailed guides on each solar eclipse in the coming weeks.

-Lead photo credit: The moon meets Venus in 2016. Photo credit and copyright: Sharin Ahmad.

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