Skywatch for the week of September 12, 2022
Mon Sep 12, 2022 SCUTUM
The small constellation of Scutum, the “shield of Sobieski,” has no bright, or even middling-bright stars within its borders. It’s wedged into the summertime Milky Way, between Aquila the Eagle, Sagittarius the Archer and the Serpent’s Tail, (Serpens Cauda,) and finding it is more like a process of elimination than actual discovery. It was introduced to star charts by the astronomer Johannes Hevelius to commemorate the lifting of the siege of Vienna which had happened on September 12, 1683. King Jan Sobieski of Poland led his hussars and men gathered from England, France, Germany, Austria, and even a great many displaced Tatars who had settled in Poland, in an attack that routed the Turkish army, which had lain siege to Vienna. Scutum has a few star clusters plus a planetary nebula, and even a pulsar.
Tue Sep 13, 2022 ELEVEN DAYS MISSING!
Here in America, there was no September 13th in the year 1752. There wasn’t a 3rd through the 12th either! The Julian calendar, established by Julius Caesar, was inaccurate; it was behind by ten days when Pope Gregory introduced the Gregorian calendar to Catholic countries in 1582. But England and its Protestant colonies kept using the old Julian calendar, until 1752, when, in order to fix the calendar, eleven days had to be chopped out. Riots broke out in London as landlords charged their renters a full month’s rent, even though the month was just 19 days long. “Give us back our eleven days!” they shouted. But in America, Ben Franklin counseled his readers not to “regret.. the loss of so much time,” but to give thanks that one might “lie down in Peace on the second of the month and not… awake till the morning of the 14th.”
Wed Sep 14, 2022 MARDUK BRINGS ORDER OUT OF CHAOS
In ancient Babylon, the story was told of how the Universe began with the watery chaos, known as Mammu. Out of Mammu came a monstrous dragon named Tiamat. Tiamat then spawned the Babylonian gods, but in time she decided to destroy them. But her grandson Marduk fought and defeated her and made her body into the framework for the cosmos. Half of her became the sky, where Marduk set the god Anu; the other half was made into the foundations of the earth, and Marduk made Ea its god. Marduk became the principle sky god, like Zeus in ancient Greece, and gave other gods responsibilities for the southern and northern skies and their constellations, while Marduk reserved the planets and stars of the zodiac for himself. And old Tiamat? You can see a vestige of her in the constellation Draco the Dragon, winding between the Big and Little Dippers tonight.
Thu Sep 15, 2022 YOUR WEIGHT ON OTHER WORLDS
The terms, “mass,” and, “weight,” are often used interchangeably. But this only works on the planet Earth, because while mass measures the amount of matter, or stuff, that the object contains, weight very much depends on how much gravity is exerted on that mass. Go to another planet or moon or asteroid, and while your mass remains the same, your weight changes, depending on how much gravity that other world possesses. The moon has 1/6th the Earth’s gravitational pull, so you weigh 1/6th what you’d weigh on Earth. If you weigh 180 pounds, then on the moon you’d weigh a mere 30 pounds – just divide your earth weight by six, and that’s all there is to it. You’d weigh about 10% less on Venus, but 3 times more in the high cloud tops of Jupiter. And on tiny Deimos, a Martian moon, you could launch yourself into a low orbit just by running and jumping!
Fri Sep 16, 2022 THE EARTH’S ORIENTATION IN SPACE
If you can imagine extending the Earth’s north and south poles out into space, you’d find a celestial north pole and a celestial south pole. Extend the Earth’s equator outward, and you can establish a celestial equator in the heavens as well. Polaris, also called the North Star, lies very close to our north celestial pole; but there is no bright South Star to find at the earth’s south celestial pole. As our Earth orbits the sun, the path it follows is not the celestial equator, but another line called the ecliptic, which is inclined 23 and a half degrees to the equator. Now while our planet orbits the sun, the sun in turn orbits the center of our galaxy – but our solar system’s orientation with that path is about 60 degrees over from straight up and down – we’re moving sideways through the Milky Way!