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By the Light of the Flower(y) Moon

by Geoff Chester, USNO Public Affairs | 02 May 2023

by Geoff Chester, USNO Public Affairs | 02 May 2023

The Full Flower Moon rising, 2020 May 7, imaged from Alexandria, Virginia
with a Canon EOS Rebel SL2 DSLR. HDR composite of 5 frames.

The Moon dives toward the southern reaches of the ecliptic this week, joining the rising constellations of the summer sky.  Full Moon occurs on the 5th at 1:34 pm Eastern Daylight Time.  May’s Full Moon is popularly known as the Flower Moon, due to the blankets of wildflowers that bloom in Northern Hemisphere woods and fields.  Other names include the Grass Moon, Egg Moon, and Planting Moon.  On the evening of the 3rd, look for the Moon just two degrees north of the bright star Spica in the constellation of Virgo.  On the 6th Luna rises just before the ruddy star Antares, the “heart” of Scorpius, the Scorpion.

The Flower Moon will wash out the view of many of the springtime constellations, but in early May you can still see the familiar figure of Orion, the Hunter, dipping toward the western horizon as evening twilight deepens.  Besides his famous “Belt Stars”, Orion’s most distinguishing feature is the red-tinted star Betelgeuse, which marks one of the Hunter’s “shoulders”.  In ancient Greek mythology, Orion was a half-mortal, the son of Neptune and the Gorgon Euryale, and developed great prowess as a hunter.  However, he was also brash and boastful, and when he told the Earth Goddess Gaia that he would slay every animal on the planet, she decided to put Orion in his place.  

For this task she sent a lowly scorpion, which crept up on the Hunter and stung him in the foot.  The scorpion’s venom came close to killing Orion, but at the last minute he was saved by an antidote provided by the healer Ophiuchus, who was also known as Asclepius in other variations of the myth.

Zeus placed Orion, the scorpion, and Ophiuchus in the sky, but arranged it so that Scorpius and Orion are never in the sky together.  Ophiuchus stands above Scorpius to be ready with another antidote should the scorpion strike again.

Just as the constellation of Orion has a red-hued first-magnitude star, so does Scorpius.  Antares marks the heart of Scorpius, and from our temperate latitudes rises in the southeast as Betelgeuse sets in the west.  Scorpius will dominate the southern horizon as one of summer’s signature constellations; during May you can see it well after midnight.

These two red stars are members of a group known as “red supergiant” stars, which are very massive stars close to the end of their evolutionary tracks.  They are fusing hydrogen and helium in concentric shells, building up iron in their cores.  Their surfaces are relatively cool, but their girths are enormous.  Place one in the Sun’s position in our solar system and Earth’s orbit would be inside its outer layers.  Such stars spend a very short time in this stage; as iron accumulates in the core the star becomes unstable, collapsing on itself in a supernova explosion.

There are a few bright stars to see while the Flower Moon brightens the sky.  The most prominent of these is Arcturus, which dominates the eastern sky during the evening hours.  Arcturus is another reddish hued giant star and represents the fate of our Sun some three billion years from now.  It has exhausted the hydrogen in its core and now fuses hydrogen in a shell that is slowly expanding.  This process increases its size and luminosity.  When the Sun reaches this stage of its evolution, Earth will become a barren, lifeless cinder.

The bright glow of Venus continues to be the focus of attention in the evening sky.  She pops into view immediately after sunset, and if you know where to locate her relative to your horizon you can glimpse her before the Sun quits the sky.  Venus moves into the constellation of Gemini this week, and will reach the northernmost declination of the current evening apparition next week.

Mars continues to trek eastward through the stars of Gemini.  This week you will find him below the constellation’s bright stars, Castor and Pollux.  The three objects are similar in brightness, but Mars is still easily identified by his ruddy tint.

The yellow glow of Saturn gradually creeps higher in the southeastern pre-dawn sky.  The ringed planet will spend the rest of the year among the faint stars of Aquarius and will reach opposition in late August.


Commander, Naval Meteorology and Oceanography Command | 1100 Balch Blvd. | Stennis Space Center, Mississippi 39529

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