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Beware of the Demon Star!

by Geoff Chester, USNO Public Affairs | 15 November 2022

by Geoff Chester, USNO Public Affairs | 15 November 2022

Jupiter, 2022 November 15, 00:37, imaged from Alexandria, Virginia

The Moon wanes in the morning skies this week as she courses her way through the rising stars of the spring constellations.  New Moon occurs on the 2erd at 5:57 pm Eastern Standard Time.  If you’re up before the Sun this week look for Luna near the bright star Regulus in the constellation of Leo, the Lion on the mornings of the 16th and 17th.  On the morning of the 21st you will find her slender crescent just to the northeast of the star Spica in the constellation of Virgo.

With the Moon retreating into the morning sky it’s time for the November observing campaign for the Globe at Night citizen science program.  The crisp nights of autumn are well-suited for counting the stars in a particular region of the sky since the haze and humidity of the warmer months isn’t present.  I have found that I can see stars that are half a magnitude fainter in the colder months from my suburban yard than I can see during the summer months.  The featured constellation for November is Pegasus, the Winged Horse, which crosses the meridian between 8:00 and 9:00 pm local time.  Most of us in urban and close-in suburbs should have no trouble identifying the constellation’s main stars, which form a distinctive square asterism.  As you move to darker locations you should be able to see fainter stars filling the square’s interior.  Under ideal circumstances from rural sites it’s possible to glimpse up to a dozen faint stars within the asterism.  Whatever you see, report your observations via the Globe at Night Web App.

One of the more distinctive constellations of autumn, Perseus, the Hero, can be seen climbing in the eastern sky during the mid-evening hours.  Perseus trails the distinctive “W”-shaped constellation of Cassiopeia, and to my eyes resembles a wishbone.  Its brightest star, Mirfak, is one of the brighter stars of the autumnal sky.  The constellation’s second-brightest star isn’t always the holder of that distinction.  Algol is a variable star whose apparent brightness fades by over a full magnitude every 2.86 days.  It remains at this minimum for about 10 hours, then brightens back to its “normal” second-magnitude appearance.  This behavior may have first been documented in ancient Egypt some 3200 years ago, and it received its name from Persian astronomers in the 10th Century who dubbed it “Ra’s al-Ghul”, the “Head of the Demon”.  In Greek mythology it represented the eye of the gorgon Medusa, whose severed head was carried by Perseus to his daring rescue of Andromeda from Cetus, the Sea Monster.  This week Algol reaches minima in brightness on the 19th at 10:25 pm and the 22nd at 7:14 pm EST.  

The Leonid meteor shower is currently under way, appearing to radiate from the “head” of Leo, the Lion, which rises in the late evening.  This shower is usually not one to excite people enough to get up in the wee morning hours, but this year just may hold a surprise.  The shower results from dusty debris sputtered off the periodic comet 55P/Tempel Tuttle, which orbits the Sun once every 33 years.  The Leonids thus tend to have bursts of great activity in 33-year intervals.  The display of 1833 was the most intense meteor display on record, with “shooting stars” falling from the sky like rain drops.  Similar displays occurred in 1866, 1966, and 1999.  In 2001 Earth encountered a previously unknown stream of comet debris, and I counted over 400 meteors in 30 minutes from a park in suburban Virginia.  This year there is a possibility of another outburst from another newly-charted comet streamer.  Your best time to look for this potential activity between 12:30 and 1:30 am EST on the 19th here in the Washington area.  Face toward the east to see if the predictions bear fruit.
Saturn is now best seen in the early evening hours.  The ringed planet is at his highest in the south at around 6:00 pm local time.  His southerly declination means that you will have about two hours to have a good look at him through the telescope before he sinks into denser layers of our atmosphere.

Jupiter appears just after sunset high in the southeastern sky.  As evening twilight ends Old Jove climbs to his highest point in the sky, well above the southern horizon, just after 8:00 pm.  This put him well above the turbulence of Earth’s atmosphere for several hours of prime observing time.  Any telescope will show the four bright moons first documented by Galileo in 1610.  Their configurations change from night to night, and if two of them happen to be passing each other you can watch the changes in their positions over a matter of minutes.  Telescopes of six inches or larger aperture will show lots of detail over his alternating dark belts and bright zones in his turbulent atmosphere.
Ruddy Mars climbs steadily into the evening sky from the northeastern horizon.  By 10:00 pm he begins to steal some of Jupiter’s thunder thanks to his surrounding luminaries of the Great Winter Circle.  The red planet will reach opposition in a few more weeks, and he will enjoy a prominent place in the sky for the rest of the year.


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

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