Skywatch for the week of November 23, 20202
Mon Nov 23, 2020 BLACK HOLES PROPOSED
On November 26th in the year 1783, British scientist John Michell first proposed the existence of black holes, suggesting that there might be super-dense stars with powerful gravitational fields that could keep light from leaving them, rendering themselves invisible. This idea was far ahead of its time, coming as it did shortly after the American Revolution. But he was right, and only in the past several decades have we found evidence for these cosmic dead ends in space. There is a black hole above us tonight. Vega, Altair and Deneb, three bright stars that form the Summer Triangle are in the west sky this evening. We believe there's a black hole in the middle of the triangle – it’s called Cygnus X-1. We can't see it directly; these things are literally out-of-sight, but there is something there, because there’s an incredible amount of x-rays pouring out of this region, made, we think, by the black hole's gravity.
Tue Nov 24, 2020 EDWIN HUBBLE AND HARLOW SHAPLEY
Two 20th Century American astronomers were born this month: Harlow Shapley on November 2nd, 1885; and Edwin Hubble on November 20th, in 1889. Both these men made remarkable discoveries about our Universe. Shapley discovered that our sun and 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 was able to measure 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.
Wed Nov 25, 2020 HERCULES’ AUTUMN ZODIAC
Hercules was one of ancient Greece’s most revered heroes. Even the] heavens were a veritable picture-book that chronicled his adventures. 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.
Thu Nov 26, 2020 WHY BUY A TELESCOPE?
You can spend lots of money buying a telescope and then be unhappy with the results. Before you buy one, ask yourself: what do you expect the telescope to do? If you want to see planets, nebulas and galaxies looking like they do in books and magazines, then you need the Hubble Space Telescope. We already have one of those, so you don’t have to buy another, just get the pictures, it’s a lot cheaper. The truth is that most small telescope views fall far short of the incredible images that we get from great observatories or space telescopes. So why buy a telescope? Well one of the principle joys of the telescope is the excitement of finding these objects in the sky, and knowing that they really are out there. A good starter telescope is a Newtonian reflector with a 6 inch mirror on a Dobsonian mount, which uses big one and a quarter inch eyepieces. Such an instrument should cost between 200 – 400 dollars. Begin your research on the internet.
Fri Nov 27, 2020 Fri Nov 29, 2019 CHRISTIAN HUYGENS AND HIS DISCOVERIES
On November 29, 1659, the Dutch astronomer Christian Huygens made the first map of Mars. Early telescopes were primitive. A lot of patience and sometimes a lot of imagination were needed to see details through the eyepiece. When, for example, Galileo first saw Saturn through a twenty-power telescope in 1610, he thought it had "handles" on either side of it. Forty-five years later Huygens observed Saturn though a much better telescope, and announced that Saturn possessed "a thin, flat ring..." Most astronomers didn’t believe him, until they too were able to see for themselves. Four years later, Huygens made his sketches of Mars, and by watching its dark features drift across the Martian surface, figured out that Mars rotated about once every 24 hours, same as Earth. Huygens also found Saturn’s largest moon, Titan, discovered that Jupiter bulges in the middle, and built the first pendulum clock.