Orion is setting as evening begins. Gemini is above it and sets not long after. Leo is on the meridian as darkness sets in. Hercules and Boötes are rising. By midnight, the great celestial birds Cygnus and Aquila are rising. Look for Pegasus and Capricornus rising just before the sun’s morning light takes the stars away.
Venus continues its reign of the evening sky. Mercury moves up between the Hyades and Pleiades below Venus around the middle of the month. The messenger planet quickly leaves them behind and passes Venus on the 21st. The waxing crescent moon provides the two planets company on the 23rd and 24th. Mercury is still heading eastward, attempting to go deeper into the night sky as Venus recedes sunward into the sun’s evening glow at month’s end. You’ll find Mercury near Tejat and Propus in Castor’s (one of the twins of Gemini) feet in the last few evenings of May.
As Comet C/2019 (Y4) Atlas has broken up into numerous small pieces, we should no longer expect a spectacle of it. Astronomers had hoped it would rise to naked eye brightness in May as it passes closest to Earth on the 23rd at 72 million miles (116 million km). For what it’s worth, the remnants will be moving in the area to the right of Venus and Mercury.
In our morning sky, see Jupiter and Saturn nearly standing still next to each other between Capricornus and Sagittarius while Mars moves eastward from Capricornus to Aquarius this month. A waning gibbous moon will pass by the two big planets on the 12th and the red planet on the 14th and 15th.
Look for Eta Aquariid meteors on the 4th and 5th. This is a better shower from the southern hemisphere, but it’s not bad for northern observers. In a good year, you could see up to 60 per hour south of the equator and about half that many in northern locations.
This month’s lunar circumstances: The moon crosses the equator northward on the 5th, is at perigee on the 6th, and is full on the 7th. The perigee at 223,500 miles (359,600 km) the day before full moon makes it another so-called supermoon. Northern lunistice is on the 11th. Last quarter is on the 14th. The moon is on the equator again, going south on the 18th. The same day, it’s at apogee 252,000 miles (405,600 km) distant. New moon is on the 22nd. Southern lunistice is on the 25th. And first quarter is on the 31st.
Notable conjunctions this month: the moon is 4.0° from Regulus on the 2nd. Mercury is at superior conjunction on the 4th. The moon passes 2.2° from Jupiter and 2.6° from Saturn on the 12th. Then it passes 2.6° from Mars on the 15th and 3.6° from Uranus on the 20th. Mercury and Venus are 0.9° apart on the 22nd. The moon is 3.7° rom Aldebaran on the 23rd, 3.6° from Venus on the 24th, and 2.7° from Mercury also on the 24th. The moon passes 4.5° from Pollux on the 26th and 4.1° from Regulus on the 29th.
Mercury is at perihelion on the 10th. It will be 28.5 million miles (45.9 million km) from the sun.