The Sky This Week
U.S. Naval Observatory's Weekly Blog

In the Merry Month of May

by Geoff Chester, USNO Public Affairs
03 May 2022
The Moon, Mercury, and the Pleiades, imaged 2022 May 2 from Alexandria, Virginia Supernova SN 2022hrs in NGC 4647, imaged 2022 April 30 at Shoestring Observatory, Alexandria, Virginia

The Moon waxes through her crescent phases in the evening sky this week, passing through the last of winter’s stars before moving into the constellations of spring.  First Quarter occurs on the 8th at 8:21 pm Eastern Daylight Time.  Luna will pass just over two degrees below the star Pollux in Gemini on the evening of the 6th.  On the following night use binoculars to see the Praesepe or “Beehive” star cluster just over three degrees south of the Moon’s fattening crescent.  On the 9th she lies about midway between Regulus, the brightest star in Leo, the Lion, and Algieba, the golden double star that marks the back of Leo’s “mane”.

For those of you who like to keep track of astronomical oddities, we have just passed another of the so-called “cross quarter” days in traditional seasonal calendars.  May 1st was May Day, which lies roughly halfway between the vernal equinox and the summer solstice.  It was considered to be the beginning of summer in the time of the Roman Republic and was celebrated as “Floralia”, after Flora, the goddess of flowers.  Theater performances and sporting events were observed over several days, and those who indulged in the fruit of Bacchus pelted each other with flowers and various types of produce.  Another festival, “Maiouma”, began to take root in the 2nd Century CE, which involved much more lascivious behavior that lasted for a month.  Over time these celebrations were adopted into Germanic and Celtic traditions, and many European countries still celebrate the day with May Queens, dancing around the May Pole, and general merrymaking.

As the nights of May pass, the time for dark-sky observing rapidly wanes.  Astronomical twilight ends at around 10:00 pm local time and begins at around 4:30 am here in the Washington area, and the darkness is even shorter as you move farther north in latitude.  This is also the time of year when we have a view away from the plane of the Milky Way out into intergalactic space, and the paucity of stars is more than compensated by the thousands of external galaxies that are within the grasp of large amateur telescopes.  I must admit that this is one part of the sky that I have never fully explored from a dark sky site, but there have been a few precious nights that I have had a chance to spend a few hours at the eyepiece which have revealed hundreds of these distant star-filled smudges to my gaze.  There is something very special in seeing half a dozen galaxies in the same field of view, then realizing that each of them is a collection of hundreds of billions of stars at distances that are almost impossible to comprehend.  However, even from the middle of the city it is possible to see some of these “island universes” thanks to modern digital imaging.  A case in point arose this past week, when I received word that a bright supernova had occurred in a galaxy that I had looked at many times in the past.  While I couldn’t see it visually from my light-polluted yard, I could still capture its image with my trusty 4-inch refractor from my driveway.  The supernova occurred about 63 million years ago in a galaxy known as NGC4647, and its light exceeded the brightness of all of the galaxy’s other stars combined.  It represented the cataclysmic destruction of a star that occurred shortly after the extinction of dinosaurs here on Earth.  

The early evening sky finally has a planet to look at, but it’s the most notoriously difficult one to see.  Mercury never strays far from the Sun and its attendant glare, but you have a chance to spot him in the northwestern sky this week.  Look for the fleet planet about 10 degrees above the horizon about half an hour after sunset.  Binoculars should help you find him in the deepening twilight.

The rest of the bright planets are strung like beads along the ecliptic in the southeastern early morning sky.  The two brightest, Venus and Jupiter, are parting ways after their close encounter over the past weekend.  To the west of Jupiter you should see the ruddy glow of Mars, which will have his own close encounter with Jupiter by the month’s end.  Saturn rounds out the group, some twenty degrees west of Mars.
 
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