Skywatch for the week of September 18, 2023
Mon Sep 18, 2023 HYPERION
On September 19, 1848, father and son astronomers William and George Bond discovered Saturn’s moon, Hyperion. To them it was just a little point of light that changed position as it orbited the ringed planet. But thanks to the Cassini spacecraft, we see it as another world. Hyperion is over 200 miles in diameter; and ordinarily such a large object should be round, but Hyperion looks pretty beat-up, covered with craters, and very irregular in shape, looking like an old meatball. Its composition is mostly water ice, with some rock and dust added for texture. Hyperion tumbles erratically as it orbits Saturn, probably owing to its irregular shape and the gravitational influence of Saturn’s biggest moon Titan. This evening you can find Saturn in the southern sky in the constellation Aquarius, but Hyperion is a little too small to see without a good telescope.
Tue Sep 19, 2023 NAME THAT CONSTELLATION - SEPTEMBER
Can you identify the twenty-ninth largest constellation? It is bordered on the north by Serpens Caput and Virgo; on the east by Scorpius and Ophiuchus; on the south by Hydra and Lupus; and on the west by Virgo again. This constellation was invented by the Romans about 21 hundred years ago when they formed it from the claws of Scorpius, and they often portrayed it as being held by Virgo, who represented Astraea, goddess of Justice. This constellation has no bright stars or notable deep sky objects like galaxies or nebulas, but tonight the waxing crescent moon appears near its brightest star, Zubenelgenubi. Can you name this star figure, the seventh constellation of the zodiac, and the only zodiacal figure that is not a person or an animal? The answer is Libra the Scales, now visible in the southwest sky after sunset.
Wed Sep 20, 2023 PLANETARIUM OPEN HOUSE
On Saturday, September 23rd there will be a free open house at the Hallstrom Planetarium on the Fort Pierce campus of Indian River State College in Fort Pierce. At 6 pm I will be giving a talk about the current night sky in the planetarium theater, and I’ll also play a few trailers from our upcoming shows, including one on black holes, another on the earth’s oceans, and even one where we show you the constellations as seen from below the equator. We’ll also provide telescopic views of the moon and the planet Saturn, weather permitting, courtesy of the Treasure Coast Astronomical Society and our student club, Hallstrom Astronomy Society. Oh, and now we have a gift shop too! I’ll see you at the Planetarium at 6 pm on Saturday. No tickets are needed, the talk and the telescope viewing are free.
Thu Sep 21, 2023 HG WELLS, GUSTAV HOLST
A musician and a science fiction writer were both born on September 21st: H. G. Wells in 1866; and Gustav Holst in 1874. Wells wrote, “The Invisible Man,”, “The Time Machine,” and “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 astronomer Percival Lowell had recently announced his discovery of canals on Mars (Observing Mars through a telescope, Lowell mistook natural linear features like the Mariner Valley for canals, which suggested to him that life must exist on the red planet. In 1915 Gustav Holst 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, including Mars.
Fri Sep 22, 2023 FIRST DAY OF AUTUMN, PLANETARIUM OPEN HOUSE
After midnight tonight, Autumn will begin. At 2:50 AM, eastern daylight time on September 23rd, we will be at the autumnal 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”. As Fall begins here, Spring will begin in earth’s southern hemisphere. We will be observing the seasonal change here at Indian River State College by holding a free open house in the Hallstrom Planetarium theater. Come on by anytime between 6 pm and 9 pm this Saturday – that’s tomorrow - and catch a live star talk, or, weather permitting, look at the moon and the planet Saturn through telescopes provided by members of the Treasure Coast Astronomical Society.