Here is a listing of celestial events you might want to look for during these spring nights in May. All times are listed as Eastern Daylight Time for the Northern Hemisphere.
Take note that we sometimes will use angular degrees to define the separation between two objects, such as (for example) the Moon and a bright planet. Keep in mind that the width of your clenched fist, held at arm’s length, measures roughly 10°.
May 12—Venus is a rather difficult sight as May begins, setting only 45 minutes after the Sun for viewers at mid-northern latitudes. However, the planet’s visibility improves considerably during the month. By May 31st, Venus’s altitude at sunset has increased from 8° to 14° and the bright world doesn’t set until about 1 hour 25 minutes after sundown. Soon after sunset this evening, an exceptionally thin (1 percent illuminated) lunar crescent might be glimpsed about 1° to the lower left of Venus.
May 13 – This evening, it’s Mercury’s turn to be visited by the Moon. It’s still an extremely slender (4 percent illuminated) crescent when it appears about 3° to the left of Mercury. They’re low in the west-northwest at dusk, setting before the sky is fully dark.
May 15--This evening, Mars can be found at nightfall, sitting about 1¾-degrees to the upper left of the waxing crescent Moon. Mars is in Gemini, fairly high in the west at dusk, 11° below Pollux and Castor. It passes 5° south (lower left) of Pollux on May 31st. In a telescope, the Red Planet is a featureless little dot. It now glows only 1/53 as bright as it did last October!
May 17--Today Mercury reaches “greatest elongation,” 22° east of the Sun, and is visible in a completely dark sky. This rocky little world is now only half as bright as was at the start of the month, and its tiny disk is only 35 percent lit. The planet fades much more rapidly in the following days, becoming too faint to observe by May 25th. It will arrive at inferior conjunction with the Sun on June 10th.
May 19 – First Quarter Moon at 3:12 p.m. In this phase, the Moon looks like a half-Moon in the sky. One-half of the Moon is illuminated by direct sunlight while the illuminated part is increasing, on its way to becoming a full Moon.
May 26 – May’s Flower Moon turns 100% full at 7:14 a.m. In this phase, the visible Moon is fully illuminated by direct sunlight. Though the Moon is only technically in this phase for a few seconds, it is considered “full” for the entire day of the event and appears full for three days.
Supermoon Alert! Because perigee (the closest the Moon comes in its orbit to Earth for the month) occurs the night before at 9:55 p.m., at a distance of 222,023 miles, we are calling this full Moon a “Supermoon,” the second and last for 2021 (April’s was the first). This will lead to an unusually large range of tides during the next few days.
There will also be a total lunar eclipse this morning, that will be best seen from the western half of the United States just before sunrise.
Lunar eclipses are known for turning the Moon a reddish color, which some refer to as a “Blood Moon.” The reddish color will be visible everywhere where the total phase will be visible (where the Moon is above the horizon during the total phase of the eclipse). That means the Western US will get a good sight of it. In the Eastern half of the country, unfortunately, the Moon will set prior to totality, so we miss out.
May 29—Mercury Retrograde begins (ends June 21). The term retrograde comes from the Latin word retrogradus, which literally means, “backward step.”
May 31 –Set your alarms! Early risers will enjoy seeing the waning gibbous Moon just 5½° to the lower left of Saturn during the predawn hours.
Our schedule is adapted from “Skylog,” a regular feature appearing in Natural History magazine, written by Mr. Rao since 1995.
This post was re-used from the farmers almanac. See full post HERE.