Minnesota Starwatch
SEPTEMBER 2023
In September the fall constellations move to front and center in the south. They include Aquarius and Pisces, which are famous but dim. On the bright side, this year Jupiter joins Saturn in the evening sky. Jupiter rises in the east-northeast by 11 p.m. On the 1st, if you want to identify these two planets, a fat waning moon helpfully positions itself midway between Jupiter, to its lower left, and Saturn, to its upper right. On the 26th, a waxing moon hangs below Saturn. Grab a star chart and look for faint, scraggly Aquarius, Saturn’s current constellation of residence. Also find the Great Square of Pegasus and the Circlet of Pisces, a rather dim ring of stars below and slightly west of the Great Square. And don’t forget the Summer Triangle. September is the best time to see these three bright stars, because they now appear high in the south at nightfall. If you have no binoculars, it still should be easy to find the Northern Cross stretching southwestward from Deneb, the star at the Triangle’s northeast corner. In the predawn sky, Venus appears below the Gemini twins— Castor and Pollux—and Procyon, in Canis Minor, the little dog. A waning moon hangs near Pollux on the 10th, and closer to Venus the next two mornings. Note how Venus, the brightest planet, compares to Sirius, the brightest star. Sirius shines to the right of Venus, and at nearly the same altitude, all month. The evening of the 28th, the third super moon in a row rises, becoming full at 4:57 a.m. the next morning. As the second full moon in a calendar month, it’s also a blue moon. Fall arrives with the autumnal equinox at 1:50 a.m. on the 23rd. At that moment the southbound sun officially crosses the equator, and Earth will be lighted from pole to pole.
AUGUST 2023
August serves up a smorgasbord of celestial delights, starting with a full “super” moon on August 1. As
it rises that evening, the moon will look bigger and brighter than usual, thanks to being less than a day from perigee, its closest approach to Earth in a lunar cycle. Saturn begins August very low in the east at nightfall. All month long it climbs higher as it drifts westward. On the 27th it reaches opposition, when Earth laps it in the orbital race and it appears opposite the sun in the sky. Mid-month will be a great time to view the ringed planet, with a small telescope if possible, because no moon will interfere. In the last few days of August, you may c
atch Jupiter rising in the east in the late evening. Don’t confuse it with Capella, the bright star low in the northeast on those nights. Also at month’s end, Venus rockets into the
eastern predawn sky. Our sister planet joins Sirius—the night sky’s brightest star—and all the iconic winter constellations.The night of August 30, we’re treated to a second super moon. It rises less than an hour before reaching perfect fullness and on the same day as perigee. As the second full moon in a calendar month, it will be dubbed a blue moon. The renowned Perseid meteor shower is expected to peak the night of August 12 to 13. This should be a good year for the shower because we’ll have five hours of moonless sky, starting around 10 p.m. August 12. The Perseids represent the fiery demise of dust particles left by Comet Swift-Tuttle, which last whipped around the sun in 1992 and won’t return until 2125. According to NASA, the nucleus of Swift-Tuttle is about 16 miles across, or about
twice the size of the rock believed to have wiped out the dinosaurs.
JULY 2023
In July Venus ends its long run as an evening star by plummeting into the sunset, a spectacular fall that begins its next trip between Earth and the sun. But it won’t be gone for long. Our brilliant sister planet will reappear in the morning sky in the last days of August. At nightfall the Summer Triangle of bright stars rides high in the east to southeast. Its brightest star is Vega, in Lyra, the lyre. The lyre, often associated with the mythical Greek musician Orpheus, is represented by a parallelogram of stars below Vega. The next brightest Triangle star is Altair, in Aquila, the eagle. The third Triangle star—Deneb—forms the tail of Cygnus, the swan, and the “head” of the Northern Cross. Grab your binoculars and explore these stars and the whole Triangle area. In the predawn sky, Saturn and Jupiter appear low in the southeast and east, respectively, on July 1. As the month goes by, both planets drift higher and westward. Low in the northeast is the brilliant star Capella, in Auriga, the charioteer. The evening of the 2nd, a super moon—a full moon that’s near the closest point to Earth in a lunar orbit—rises in the aptly named Teapot of Sagittarius. That night the moon follows a low trajectory across the night sky and sets in the west half an hour before sunrise on the 3rd, shortly before reaching perfect fullness. The waning moon visits Saturn on the 7th and Jupiter on the 11th and 12th. On the 14th and 15th, an old moon makes a pretty sight with Jupiter, Capella, and the Pleiades star cluster. The star below the Pleiades will be Aldebaran, the eye of Taurus, the bull. On July 6 Earth reaches aphelion, the farthest point from the sun in its orbit. At that moment our planet will be 94.5 million miles from its parent star.
The University of Minnesota offers public viewings of the night sky at its Duluth and Twin Cities campuses. For more information, see:
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics: www.astro.umn.edu/outreach/pubnight
Check out astronomy programs, free telescope events, and planetarium shows at the University of Minnesota's Bell Museum:
www.bellmuseum.umn.edu/astronomy
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu
6/22/23 Contact: Deane Morrison, University Relations, (612) 721-6003, morri029@umn.edu.
JUNE 2023
As June opens, Venus forms a line with the Gemini twins. Nearby, Mars is poised to drift through the subdued but lovely Beehive star cluster in Cancer, the crab. At nightfall June 1 and 2, look for brilliant Venus above the western horizon. To the right of Venus, Pollux—the brighter Gemini twin—and Castor complete an almost perfectly straight line. Above and left of Venus, Mars still ornaments the evening sky. On June 1, 2, and 3, grab your binoculars and watch Mars sail through the Beehive cluster. The Beehive is also known as Praesepe, Latin for “manger.” As Mars leaves the Beehive, it passes between two somewhat bright stars that frame the manger. These are the northern and southern asses—Asellus Borealis and Asellus Australis, respectively—which feed at the manger. Looking upward and leftward again, the bright spring star Regulus, the heart of Leo, the lion, is closing in on the two planets. Watch this space between Tuesday and Friday, the 20th and 23rd, as a young waxing moon sweeps past Venus, Mars, and finally Regulus. June’s full moon rises big and round the evening of the 3rd. It crosses the night sky next to Antares, the gigantic red heart of the summer constellation Scorpius. In the predawn sky, Saturn is well up in the southeast and Jupiter spends the month climbing up from the eastern horizon. If you’re out early enough on the 14th, don’t miss the pretty pairing of a waning crescent moon and Jupiter. Summer arrives with the solstice at 9:58 a.m. on the 21st, when the sun reaches a point over the Tropic of Cancer. At that moment an observer in space would see sunlight stretching from the Antarctic Circle up to the North Pole and over to the Arctic Circle on the dark side of the planet.
The University of Minnesota offers public viewings of the night sky at its Duluth and Twin Cities campuses. For more information, see:
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics: www.astro.umn.edu/outreach/pubnight
Check out astronomy programs, free telescope events, and planetarium shows at the University of Minnesota's Bell Museum:
www.bellmuseum.umn.edu/astronomy
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu
5/18/23 Contact: Deane Morrison, University Relations, 612) 721-6003, morri029@umn.edu.
MAY 2023
During May, brilliant Venus holds its own above the western horizon as the last of the bright winter stars stream past it.
Our sister planet begins the month by gliding between Betelgeuse, in Orion, and Capella, in Auriga, the charioteer. Betelgeuse, to the lower left of Venus, is outshone by both the planet and high, brilliant Capella. As those stars drop away, Venus passes through Gemini, all the while following a course toward Mars, which appears to be fleeing its approach.
Mars starts the month below Pollux, the brighter of the Gemini twins. As Gemini sinks, Pollux glides past the red planet.
The assemblage is enhanced between Monday and Wednesday, the 22nd and 24th, when a waxing moon joins the stars and planets. The bright star passing to the lower left of Venus those nights is Procyon, in Canis Minor, the little dog. The moon appears next to Pollux on the 23rd and above Mars on the 24th.
The moon begins the month below the triangular hindquarters of Leo, the lion. Leo’s head—the backward question mark of stars known as the Sickle—now dips a bit as the constellation begins its inevitable descent into the sunset. On the 3rd, the moon shines just above Spica, the only bright star in Virgo, the maiden. Above them, radiant Arcturus anchors the kite-shaped constellation Bootes, the herdsman.
May’s full moon arrives at 12:34 p.m. on Friday, the 5th. The moon sets in the west shortly before sunrise that day, so your best bet may be to enjoy the moonrise on the evening of the 4th or 5th. Also in the predawn hour, a waning moon visits Saturn in the southeastern sky on Saturday, the 13th. On Wednesday, the 17th, a thin lunar crescent visits Jupiter very low in the east, in the midst of the sun’s foreglow.
The University of Minnesota offers public viewings of the night sky at its Duluth and Twin Cities campuses. For more information, see:
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics: www.astro.umn.edu/outreach/pubnight
Check out astronomy programs, free telescope events, and planetarium shows at the University of Minnesota's Bell Museum:
www.bellmuseum.umn.edu/astronomy
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu
4/22/23 Contact: Deane Morrison, University Relations, 612) 721-6003, morri029@umn.edu.
MARCH 2023
March always brings passages—winter to spring, ice to slush, sun to the Northern Hemisphere. This year, the month begins with an uncommon passage as the two brightest planets sweep by each other above the southwest horizon.
On Wednesday, the 1st, Jupiter passes within a moon width of brilliant Venus. The gap between them quickly widens as Jupiter falls into the sun’s afterglow. On Wednesday, the 22nd, a thin crescent moon appears above Jupiter about 40 minutes after sunset. The next night, the moon hangs below Venus.
East of the planetary pair, Mars rides high at nightfall as the bright winter stars stream past it. In mid-month Mars glides between Betelgeuse, the giant red star at Orion’s right shoulder, and brilliant Capella, in Auriga, the charioteer. At month’s end the red planet will be heading into Gemini. Enjoy this feast of stars and Mars now, before the winter constellations also slip into the sunset.
March’s full moon arrives at 6:40 a.m. on Tuesday, the 7th, after crossing the night sky below the spring constellation Leo, the lion. The moon sets in the west shortly after reaching fullness, so plan accordingly.
Spring begins with the vernal equinox at 4:24 p.m. Monday, the 20th. At that moment the sun crosses the equator heading north, and Earth will be lighted from pole to pole. From then until the September equinox, the day length increases as we travel north. Also, the day length increases most rapidly near the spring equinox because the sun is then moving most rapidly northward.
If you’re out at the end of evening twilight between the 10th and the 22nd, look for a faint, broad cone of light extending up from the western horizon along the sun’s path. This is the elusive zodiacal light, the result of sunlight reflecting off dust in the plane of the solar system. Recent evidence has suggested a Martian origin for the dust.
FEBRUARY 2023
In February Venus climbs above the sunset horizon and settles into its latest reign as an “evening star.” But the sun is also climbing, so we have to go out later each night to see our sister planet against a dark sky.
As Venus surges, Jupiter drops toward it, thanks to Earth leaving the giant planet behind in the orbital race. Look for Jupiter in the southwest and watch the two brightest planets draw closer each night. The pair ends the month poised to pass each other on March 1.
While Earth regularly leaves Jupiter in the dust, it can’t do that to Venus because it’s closer to the sun and speedier than Earth. Thus, Venus climbs and falls due to its own movement. When it’s an evening star it’s chasing us, but when it appears in the morning sky we’re “eating its dust.”
Mars is now high in the south at nightfall. The red planet is fading but still easy to find; look east of the Pleiades star cluster and above Aldebaran, the eye of Taurus, the bull. Also, take this chance to compare Venus, the brightest planet, to Sirius, the brightest star in the night sky. Sirius is the lowest of the bright winter stars now assembled in the southeast and shines to the lower left of Orion’s hourglass figure. Try in mid-month, when Venus will be higher at nightfall and no moon will interfere.
February’s full moon arrives on the 5th. During the moon’s next cycle it visits Jupiter and Venus on the 21st and 22nd and Mars on the 27th.
On Groundhog Day we celebrate an ancient astronomically based Celtic holiday called Imbolc, or lamb’s milk. It marked the start of the lambing season and was one of four cross-quarter days falling midway between a solstice and an equinox. How the groundhog became linked to this day isn’t clear. As for why seeing its shadow, or not, was important, one theory suggests that if the day was cloudy and shadowless, it portended rain and softening farm fields. But a clear and cold day signaled a more stubborn winter.
JANUARY 2023
The new year opens with Venus climbing out of the sun’s afterglow. On Sunday, January 22, Saturn drops past Venus as Earth’s orbital motion sends the ringed planet tumbling into the sunset. Look for the pair of planets very low in the southwest just as the sky darkens.
If you catch Venus and Saturn, also turn your eyes to Jupiter, the beacon high in the southwest, and high-flying, reddish Mars, the second-brightest object in the knot of winter constellations in the east. With the right timing, you can simultaneously view Venus—the brightest planet—and Sirius, the brightest star (after the sun) and the last of the iconic winter stars to clear the eastern horizon.
January’s full moon arrives on Friday, the 6th. It rises before sunset and becomes full at 5:08 p.m. After nightfall it shines to the right of the Gemini twins Pollux (the brighter) and Castor. Between about 9 p.m. and midnight on Friday the 30th, you’ll have plenty of time to watch a waxing moon of the next cycle glide close below Mars.
In the predawn sky, the Northern Cross lies on its side below brilliant Vega, the jewel of Lyra, the lyre. On the 18th, a thin waning moon rises close to Antares, the heart of Scorpius.
Earth reaches perihelion, the closest point to the sun in its orbit, at 10:17 a.m. on the 4th, when our planet reaches its top speed. Changes in Earth’s speed go largely unnoticed, but they show up in the length of the seasons. Because Earth goes so fast in the middle of its journey from the September to the March equinox, the combined fall-winter season is about seven days shorter for us than for our friends in the Southern Hemisphere.