Skywatch for the week of November 20 ,2013
Mon Nov 20, 2023 DARKNESS WASTING TIME
I hope by now that everyone has recovered from our recent semi-annual lurch in time. After more than half a year of Daylight Savings Time, we’ve finally returned to the more sensible Standard Time. Daylight Savings Time was implemented in the United States in 1918 by the Woodrow Wilson administration, and it has been with us pretty much ever since. By setting our clocks ahead one hour in the Spring, we can stretch out the afternoon and evening daylight periods. But for astronomers, Daylight Savings Time is known as Darkness Wasting Time, because it makes us wait an extra hour for the skies to darken so we can see the stars. Now as nights get longer and daylit periods shorter, and a return to Standard time, at least for now we can get some serious observing done long before the midnight hour.
Tue Nov 21, 2023 HERCULES’ AUTUMN ZODIAC
The adventures of Hercules are displayed by the constellations. The zodiac reveals many of his twelve great labors. Soon to set after the sun are the stars of Sagittarius the archer. This centaur is a depiction of Hercules’ teacher, Chiron. Well-placed in the south are a scattering of stars which mark Aquarius, the Water Carrier. This is symbolic of Hercules’ releasing the flood of river waters that cleaned the Augean stables. High in the east is Aries the Ram, a representation of the golden fleece, which Hercules pursued with his good friend Jason while he was between labors. Nearer toward the eastern horizon is Taurus; this was a wild bull which Hercules subdued in a kind of a “capture and release” program. There are more constellations connected with Hercules, but they won’t show up in our evening sky until next month.
Wed Nov 22, 2023 EDWIN HUBBLE AND HARLOW SHAPLEY
Two American astronomers were born this month: Harlow Shapley on November 2nd 1885; and Edwin Hubble on November 20th in 1889. Each made great discoveries. Shapley found that our sun & solar system were not at the center of the Milky Way Galaxy, but instead a little over halfway out, and that the Milky Way was much larger than anyone had previously thought, almost 600,000 trillion miles in diameter: big. But Shapley thought that the Milky Way was all there was to the Universe. It was Hubble who measured the distance to the Andromeda Nebula, that is galaxy, some 15 million trillion miles away, which placed it far outside our own galaxy. Hubble also found evidence that the Universe was expanding, suggesting that everything began billions of years ago in what is now called the Big Bang.
Thu Nov 23, 2023 THE MOON AND TIDAL LOCKS
Just as we experience daylit and dark periods on earth, so the moon has both day and night. But the moon spins slowly; a lunar day lasts two weeks, followed by two weeks of lunar night. The moon’s rotation period matches its revolution, so it rotates once for every one orbit. This is called a tidal or synchronous lock, an effect of the earth’s tidal pull on the moon, which has slowed its rotational speed to match its revolution. Because of this we can only see half the moon (lunar nearside;) the farside of the moon (sometimes wrongly called “the dark side,”) can never be seen from earth. Or as Pink Floyd tells us, ”There is no dark side of the moon; matter of fact, it’s all dark!” But the sun lights up the dark side, sorry, farside, just as much as lunar nearside.
Fri Nov 24, 2023 NOVEMBER FULL MOON
The moon will be full this weekend. November’s full moon is called the Dark Moon by the Celts, which recognizes the lengthening of the night as winter approaches. The Creek Indians call this the Moon When the Water is Black with Leaves, as in northern lands when leaves would drop from the trees and darken ponds and rivers. The Mandan Hidatsa people must have lived farther north, as this was their Moon When Rivers Freeze. It’s the Frost Moon for the Seminole people, and to the Tewa Pueblo this is the Moon When All is Gathered In - the late harvesting moon. It’s the Cherokee Trading Moon, and the Choctaw Sassafras Moon. But the Seneca Indians of western New York would call this the Beaver moon, in honor of Nöganyá’göh the beaver who, with the help of the fly Oshë’da’, drove off the always thirsty Oyëtani' the moose, thus saving the drinking water for the other animals.