Skywatch for the week of December 27, 2021
Mon Dec 27, 2021 TELESCOPE HELP
If on Saturday you found a telescope under your tree, and by now you still haven't figured out how to get it to work, here’s some basic advice. You've either got a reflector, which has a big mirror at the bottom of the telescope, or a refractor, usually a long tube with a big glass lens at the top. The refractor’s eyepiece, which does the magnifying, goes into the draw tube at the bottom of the scope. If you have more than one eyepiece, use the eyepiece with the biggest number - this will give you the least magnification, which is what you want to start out. You probably also have something called a Barlow lens which doubles or triples the magnification - this attachment gives you way too much magnification and makes your instrument unwieldy, so put it aside. As a general rule, don’t magnify more than 50 power for each inch of aperture, the width of your main lens or mirror.
Tue Dec 28, 2021 VENUS-MERCURY CONJUNCTION
It’s very hard to find the planet Mercury at night, because this tiny planet is just 36 million miles from the sun. So it’s sometimes in front of the sun, sometimes behind it, or at best, just a little bit to the left or the right of the sun as it travels in its orbit. But tonight you can find this elusive little world without too much trouble. Go outside at sunset, and look above the southwest horizon. There you will find a brilliant, star-like object, so bright that it will appear even before it’s dark. That’s the planet Venus. But as twilight begins, look just below and a little to the left of Venus, and that’s where you’ll see another star – another planet – Mercury. Now look a bit above and to the left of Venus, and there’s Jupiter. Finally, draw a line between the planets Jupiter and Venus, and that little yellow star in between them is actually the planet Saturn.
Wed Dec 29, 2021 JOHANNES KEPLER
Johannes Kepler was born on December 27th in the year 1571. Kepler believed in Nicholas Copernicus’ theory that the earth was not the center of the universe, but instead orbited the sun. But while Copernicus had a beautiful idea, in terms of predicting where the planets would be it didn’t work any better than the geocentric theory; both theories were riddled with errors, bad observations and mistaken assumptions. Copernicus held on to the ancient idea that the orbits of planets were perfectly circular, but the data that Kepler used, obtained from the painstaking observations of the Danish astronomer Tycho Brahe, didn’t support that notion. Unlike past theorists, Kepler refused to toss out the data. Instead he got rid of the theory and introduced a new one: the orbits of planets are elliptical. Once elliptical orbits were calculated, the motions of the planets became understandable and predictable.
Thu Dec 30, 2021 ARTHUR EDDINGTON
Arthur Eddington was born on December 28, 1882. It was Eddington who proved Einstein’s theory of general relativity. He was pretty smart, and he knew it. When someone praised him as being one of only three people who understood Einstein’s theory, Eddington replied, “Well, there’s me, and there’s Einstein. Who else is there?” Einstein’s theory of general relativity said that the gravity of a massive object, like the sun, could bend any light waves that came near it. So any stars that were along the same line-of-sight as the sun would seem to be displaced by its gravity. You can’t ordinarily see stars near the sun, because it’s too bright. But during a total solar eclipse, you can. And during a solar eclipse in 1919, observations by Eddington found that stars near the sun in Taurus, (a constellation that’s visible in our southern sky this evening,) were displaced; he had proved Einstein’s theory.
Fri Dec 31, 2021 NEW YEAR’S AVATAR
Often the outgoing year is portrayed as a very old man known as Father Time. Father Time in turn is based on the Greek mythological god Kronos, whom the Romans associated with Saturn, an agricultural god. The planet Saturn takes 29 years to orbit the sun, so to sky-watchers of long ago, it seemed as if this slow-moving, unhurried planet must somehow be associated with time. In late December great festivals like the Saturnalia were held in honor of Saturn. Gifts were exchanged, homes and streets were decorated, and everybody was in a happy party mood. After this came the solstice and celebrations of the sun, then another holiday for Janus, the Roman god of new beginnings, and for whom the month of January is named. If you want to see Saturn tonight, you’ll find it midway between the planet Venus, near the western horizon after sunset, and Jupiter, high in the southwest sky.