Skywatch for the week of November 16, 2020
Mon Nov 16, 2020 WILLIAM HERSCHEL BORN
William Herschel was born on November 15th, 1738. Herschel was a church organist in Bath, England. He also had a great interest in astronomy, and in telescopes. But most musicians don’t make much money. And telescopes were expensive. So he built his own. It was with just such a telescope that in March of 1781, William Herschel saw what he first thought to be a comet far out in space. After its orbit was checked, it was clear that the object was a planet. Herschel named it George, after the King of England. Many astronomers suggested the planet simply be called, Herschel. Eventually Uranus, who in mythology was the father of Saturn, was chosen. Herschel also found four moons: Oberon and Titania, which orbit Uranus, and Mimas and Enceladus, which orbit Saturn. And Herschel mapped the stars of the Milky Way, concluding from their distribution that the galaxy in which we live was shaped like a giant disc.
Tue Nov 17, 2020 HARLOW SHAPLEY Harlow Shapley born 11/2/1885
Over in the southwest this evening there is a concentration of globular star clusters. No, you can’t see them with the unaided eye, but with a telescope you could find them – and each cluster you see contains thousands and thousands of stars packed in tight by gravity. Globular star clusters are all around us, but about half of them are gathered into one small spot in the sky, near the constellation Sagittarius. An astronomer named Harlow Shapley, born on November 2nd, in 1885, realized the significance of this clustering of clusters. In 1920 he suggested that because the globular clusters seemed to be centered around Sagittarius, that it was probable that that marked the center of the Milky Way galaxy. He was right – our solar system is part of the Milky Way, but we’re not in the middle of it, we’re a little over halfway out toward its edge.
Wed Nov 18, 2020 CROSSING THE ASTEROID BELT
There are many asteroid belts in the solar system - they range from inside the orbit of Venus all the way out to Neptune; but most of the asteroids can be found between Mars and Jupiter. Perhaps they are leftover remnants from the solar system’s formation. Possibly they are the result of a catastrophic collision between a handful of moon-sized bodies that occurred in the distant past. It was feared that the asteroid belt would pose a hazard to spacecraft. But in November of 1972, the unmanned spacecraft Pioneer 10 found itself deep within the belt. When it emerged in February 1973, it demonstrated that navigating the belt was possible. Since then, many more spacecraft have safely made the journey: Pioneer 11; Voyagers 1 and 2; Galileo; Cassini and New Horizons. There’s a lot of space between most of the rocks, and the chances of being hit are slim.
Thu Nov 19, 2020 NAME THAT CONSTELLATION - NOVEMBER
Can you identify the 15th largest constellation? It is bordered on the north by Scutum the Shield, Aquila the Eagle and Serpens Cauda, on the south by Telescopium and the Southern Crown, on the west by Scorpius and Ophiuchus, and on the east by Microscopium and Capricornus. The center of the galaxy lies in the direction of its western border, and it contains many star clusters and star clouds, such as the Trifid and the Lagoon Nebulae. This constellation has no first magnitude stars, but a handful of 2nd magnitude stars trace out the shape of a teapot. In Greek mythology it represented Chiron, a centaur who taught Hercules and even now, guards the other constellations by keeping Scorpius at bay with his bow and arrow. November’s crescent moon and the planets Jupiter and Saturn appear within its borders at this time of the month. Can you name this star figure, the ninth constellation of the zodiac? The answer is Sagittarius the Archer.
Fri Nov 20, 2020 THE MOON IN THE SEA
When November’s moon waxes in our evening sky, it passes through the zodiacal constellations of Capricornus the Sea Goat, Aquarius the Water Carrier and Pisces the Fish; these constitute the “water signs” of the astrologer. But beyond the zodiac there are many more watery constellations, all part of the sky known as “the sea.”
In mythology this celestial sea was created by the water poured out from the jug of Aquarius in the west and by the overflow from the constellation of Eridanus the River in the East and South. Denizens of The Sea are Capricornus, Aquarius, Pisces, plus a dolphin, named Delphinus, above Capricornus, and still another fish, Piscis Austrinus, low in the south. And there’s a sea monster, Cetus, actually a great whale. At this rainy time of the year, the Sea in the Sky is aptly named.