Skywatch for the week of September 20, 2021
Mon Sep 20, 2021 FULL MOON OF SEPTEMBER
The moon is full tonight. You’ll find it rising out of the east as sunset gives way to twilight. September’s full moon is the Barley Moon of medieval England, or the Singing Moon in Scotland and Ireland. The Chinese call this the Chrysanthemum Moon, while in the Americas it is the Corn Moon. The Cherokee call it the Black Butterfly Moon or the Nut Moon. Similarly it is the Little Chestnut Moon of the Creek and the Seminole people. It is the Drying Grass Moon of the Arapaho and the Cheyenne people, and the Choctaw Indian’s Courting Moon. While the Comanche say it is the Paper Man Moon, the Mohawk call September’s Full Moon the Time of Poverty. To the Omaha Indians it is the Moon When the Deer Paw the Earth while the Sioux say it is the Moon When Calves Grow Hair.
This is also the Harvest Moon, the full moon which occurs nearest the autumnal equinox, the beginning of fall, which will be on September 22nd. The light of this full moon proved helpful to farmers who brought in their harvest of crops after sunset.
Tue Sep 21, 2021 HG WELLS, GUSTAV HOLST
Herbert George Wells was born on September 21st, 1866. Besides “The Invisible Man,” and “The Time Machine,” he wrote “The War of the Worlds,” which was published at the end of the 19th century, at a time when there was a really big “Mars mania” sweeping the planet. The American astronomer Percival Lowell had recently announced his discovery of canals on Mars (Lowell was mistaken by the way; his telescope allowed him to see natural features on Mars like the Mariner Valley, but didn’t give him enough resolution to see them as anything but vague lines which he interpreted to be canals.) But at the time it was thought that life must exist on the red planet.
Wells shares his birthday with the composer Gustav Holst, born on September 21st, 1874. He was a musician, not an astronomer, but in 1915 he wrote a piece of music that you often hear on this radio station, and also quite a bit in planetariums. It's called, "The Planets", and in it Holst wrote music to describe each of the seven known planets.
Wed Sep 22, 2021 FIRST DAY OF AUTUMN
It’s September 22nd, and at 3:21 pm, eastern daylight time - that’s this afternoon – Autumn begins. This is the autumnal or fall equinox, a point in time when, if you’re at the earth’s equator, the sun can be seen at the zenith, the top of the sky, at noon. Today, everyone around most of the world enjoys days and nights of pretty much equal length, hence the term “equinox,” which means “equal night”. From now until after the beginning of winter the sun will rise to the south of east and set to the south of west, and its noontime altitude will continue to decrease as well, as we view it from earth’s northern hemisphere.
Our planet’s rotational axis is tipped 23 and a half degrees from straight up and down, as it orbits the sun. That axis does not flip back and forth – it acts more like a gyroscope, making the sun’s path across our sky lower and lower each day as we move toward winter. Now, south of the equator, spring begins: the seasons are reversed for earth’s southern hemisphere.
Thu Sep 23, 2021 NEPTUNE’S DISCOVERY
Neptune was discovered by Johanne Galle on September 23rd, 1846. Working at the Berlin Observatory, Galle used the observatory’s nine inch refracting telescope to search for a possible eighth planet. Galle had been asked to search a particular spot in the sky by a French mathematician, Urbain Leverrier, where he’d calculated it to be.
Through the eyepiece, Galle saw a tiny, faint blue dot – was it just another star? Galle and his assistant Heinrich d’Arrest opened up their book of star maps, something called, the Berliner Akademischen Sternkarte, (I think I said that right,) and found that his star was “not on the map!” The next night they found that the tiny dot had moved against the background of fixed stars - it was a wanderer, a planet. Neptune is still in our sky, over in the constellation Aquarius in the southeast after sunset tonight, and yes, even though our planet just passed it and it’s less than 2.7 billion miles away, you’ll still need a pretty good-sized telescope to see it.
Fri Sep 24, 2021 DELPHINUS AND ARION
Near the top of the sky this evening are three bright stars spread out across the zenith. These three stars – Vega, Altair and Deneb, form the Summer Triangle. The brightest star is Vega; it marks the constellation of Lyra the Harp. In Greek mythology, the harp belonged to many people, including the musician Arion, who was rescued by the dolphin Delphinus. Arion had been thrown overboard by some greedy pirates who wanted all the gold he had earned at a concert. Before they tossed him into the ocean, they let him sing one last song, which was overheard by the dolphin.
When Arion fell into the sea, Delphinus saved him, and carried him to shore; in fact he got back before the pirates. When they got off the boat, the pirates were arrested and voted off the island. To find the harp and the dolphin, you’ll need a very dark, clear sky. Lyra is a scattering of stars near Vega, and Delphinus is a small, faint cluster of stars on the opposite side of the Summer Triangle.