For September, the new moon occurs on September 2nd. It lies just south of Venus in the dusk on September 5th. It is first quarter on September 11th. The waxing gibbous moon lies just west of Saturn in the SE twilight on September. This full moon, the Harvest Moon, on September 17th finds the moon moving through the earth’s outer penumbral shadow, with maximum slight fading at 10:44 p.m.. The autumnal equinox begins Fall this year on September 22nd at 8:44 a.m..
Mercury lies close to the old moon on September 1st in the dawn, and reaches greatest western elongation, only 18 degrees from Sun, on September 5th, and is lost in sun’s glare by mid month. Venus returned to the evening sky in August, and will dominate the western twilight through the end of 2024. It is a bright, round disk now, almost fully lit on the far side of the sun.
Mars is in Taurus in the dawn sky, moving into Gemini by month’s end. Jupiter is near Mars in Taurus, but farther away, moves much slower than Mars. But it is also much brighter, and will be coming back into the evening skies by November. But Saturn is at its best this month, reaching opposition on September 7th. But it is nearing its equinox in 2025, so its famed rings are almost closed.
To the northwest, we find the familiar Big Dipper getting lower each evening. Most know how to use the two pointers at the lower part of the bowl to find Polaris, our Pole Star, sitting about 30 degrees high all night in the northern sky for the Gulf Coast.
From the Dipper’s handle, we "arc" SE to bright orange Arcturus, the brightest star of Spring, and still well up in the western twilight. Just above Bootes, still almost overhead at twilight, is tiny Corona Borealis. We continue to wait for its "Blaze Star", T C Br, to erupt as a dwarf nova, which most astrophysicists predict would happen by this month. It last occurred in 1946, and became as bright as Polaris for several days, but has frustrated us so far. It will erupt just east of the eastern most star in the crown, epsilon Coronal Borealis, and should be making new everywhere when it blows at last. It seems to build up enough hydrogen to blown off the shell around the white dwarf every 80 years or so, but the white dwarf and its red giant companion are not destroyed and start repeating the mass transfer when things settle down after the blaze.
From Arcturus, we can spike south to Spica, the hot blue star in Virgo. Note that Spica is now low in the SW, and by September’s end, will be lost in the Sun’s glare due to our annual revolution of the Sun making it appear to move one degree per day eastward. To the Greeks, Spica and Virgo were associated with Persephone, the daughter of Ceres, goddess of the harvest. The beautiful young daughter falls for the gruff, dark god of the underworld, Pluto. He elopes with her, much to the disapproval of mother Ceres, and they marry in his underworld kingdom of Hades…a honeymoon in hell…really, he does love her as well, and the marriage itself works well. But it is the reaction of Ceres that creates alarm.
Very despondent over the loss of her young daughter to a fate as bad as death, Ceres abandons the crops, which wither. Soon famine sets in, and humanity appeals to Jupiter to save us all. Calling all together, Jupiter hears that Ceres wants the marriage annulled, Persephone loves them both, and Pluto wants his mother-in-law to stop meddling. Solomon style, Jupiter decides to split her up, not literally, but in terms of time. In the compromise, when you can see Spica rising in the east in March, it means to plant your peas. For the next six months, she visits upstairs with as very happy mama, and the crops will prosper. But now, as Spica heads west (to the kingdom of death, in most ancient legends) for six months of conjugal bliss with Pluto, it is time to get your corn in the crib. This simple story, told in some form for as long as Noah’s flood, was one of the ways our ancestors 7,000 years ago knew the solar calendar and when
to plant and harvest.
To the south, Antares marks the heart of Scorpius. It appears reddish (its Greek name means rival of Ares or Mars to the Romans) because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturn’s orbit! Near the tail of the Scorpion are two fine open clusters, faintly visible to the naked eye, and spectacular in binoculars. The clusters lie to the upper left of the bright double star that marks the stinger in the Scorpion’s tail. The brighter, M-7, is also known as Ptolemy’s Cluster, since he included it in his star catalog about 200 AD. M-6 will appear below it in the same wide binocular field.
East of the Scorpion’s tail is the teapot shape of Sagittarius, which marks the heart of our Milky Way galaxy. Looking like a cloud of steam coming out of the teapot’s spout is the fine Lagoon Nebula, M-8, easily visible with the naked eye. The center of the Milky Way lies about 25,000 light years beyond, but is hidden by gas and dust.
The brightest star of the northern hemisphere, Vega dominates the NE sky. Binoculars reveal the small star just to the NE of Vega, epsilon Lyrae, as a nice double - hence its nickname, "The Double Double". Between the two bottom stars; the Ring Nebula, "M-57", is a ring of gas and dust expelled by a dying red giant star while its core collapsed to a white dwarf. A similar fate is expected for our own sun in perhaps five billion more years. The tiny white dwarf, like the one in the T Corona Borealis nova system, has shrunk down to the size of Earth, by crushing its electron shells, so while the atomic nuclei are still intact, they are not normal atoms with chemical reactions.
To the northeast of Vega is Deneb, the brightest star of Cygnus the Swan. It was just NW of it that I discovered the brightest nova of my lifetime, Nova Cygni, on August 27, 1975. Here a shell of hydrogen around a white dwarf exploded suddenly, becoming a record (for a nova, at least) 20 million times brighter in a matter of hours. It went from not visible in any telescope to the sixth brightest star in the summer sky in less than a day, and I was looking at the right place and time to catch it still on the rise. But the total amount of expel gases was much less than in the Ring Nebula, and it faded below naked eye visibility in only two weeks. Typically several nova outbursts are found every year in our Galaxy, and they do often recur, for neither star in the close binary system are destroyed, and the mass transfer can resume soon.
At the other end of the "northern Cross" that makes up the body of Cygnus is Albireo, the finest and most colorful double star in the sky. To the south of Cygnus is Altair, the brightest star of Aquila the Eagle, the third member of the three bright stars that make the Summer Triangle so obvious in the NE these clear September evenings. South of Aquila is M-16, the Eagle Nebula. In its center is the famed "Pillars of Creation."
To the east, the Square of Pegasus rises. The long axis of the square points to the SE to Saturn in Aquarius. Jupiter will join the evening planet parade in November in Taurus. The fall constellations are returning to the eastern sky earlier each evening now.
