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Skywatch for the week of March 8,2021

Skywatch 3-8-2021.mp3

Mon Mar 8, 2021 SUN, SOLAR YEAR AND ECLIPTIC

Watch the sun and you’ll discover it gets around. But of course you can’t watch the sun - it’s too bright to look at without hurting your eyes. Actually, there are times when you can do this, but only during a total solar eclipse.)Assuming you could see the sun and stars at the same time, you’d notice the sun drifts eastward against the background of the stars, like the moon, although not as fast as the moon. If we think of the stars as being laid out on an invisible sphere, and a line on that sphere makes a 360 degree circle, then the sun moves along that line almost 1 degree a day. After 365 days, the sun would be back where it started. A solar year, then is the amount of time it takes the sun to go once around the heavens, and that invisible line that traces out its path is called the ecliptic. The constellations through which the sun passes each year make up the zodiac, and the ecliptic is its central line.

Skywatch 3-9-2021-PG1-SWTU.mp3

Tue Mar 9, 2021 BIG DIPPER, NORTH STAR AND LITTLE DIPPER

Throughout the month the Big Dipper is just off the northeastern horizon around 8 o’clock in the evening. Find someplace outside where you have a clear view toward the north, without any streetlights to interfere with your view. To find north, place the setting sun to your left. Now you’re facing north. Next point to the right – you should be pointing toward the ocean and east. Turn halfway toward the east and now you’re facing northeast. That's where you'll find the Big Dipper, standing on its handle, beginning low near the horizon. Now draw a line between the top two stars of the Big Dipper's bowl, and extend that line to the left, and it leads you to the North Star, not a particularly bright star, but it's not known for being bright, just for being in the north. The North Star, whose official name is Polaris, is at the end of the handle of the Little Dipper, which is very hard to see because its stars are fairly dim.

Skywatch 3-10-2021-PG1-SWWE.mp3

Wed Mar 10, 2021 WHY DOESN’T POLARIS MOVE?

Earth’s north pole points almost directly at the star Polaris (it’s not perfect; but, to the unaided eye, it’s close enough to be considered true north. As the earth rotates, stars rise generally out of the east and set in the west. But Polaris always remains fixed in place. It’s like spinning a basketball on your finger. There’s only one other place to put a second finger on the ball and not disrupt rotation, and that’s the top of the ball. Now think of standing on the top of the earth. Look straight up. Instead of a giant finger, you’ll see a star. That’s Polaris, and it appears on the zenith, 90 o overhead, from the Earth’s north pole, which is at 90o North latitude.If you slide down the Earth, then the North Star slides downward: at 45o North latitude, Polaris is halfway up the north sky. But if you go to the equator, 0 degrees, then Polaris is on the north horizon, and you can’t see it.

Skywatch 3-11-2021-PG1-SWTH.mp3

Thu Mar 11, 2021 URANUS DISCOVERED/PLUTO DISCOVERY ANNOUNCEMENT

On March 13, 1781, the planet Uranus was discovered by William Herschel. Herschel was a church organist and music director in the city of Bath, England. But he dabbled in other pursuits, and astronomy was his passion. Using a telescope he had built himself, he became the first person in history to discover another planet too faint to be seen with the unaided eye. About a hundred and fifty years after Uranus was discovered, the Lowell Observatory in Arizona announced the discovery of another planet. It had been found by a young observatory assistant, Clyde Tombaugh, and was named Pluto. Several years ago an international group of astronomers who had nothing better to do with their time voted to demote Pluto to dwarf planet status, but the American Astronomical Society opposes the idea. In the summer of 2015 a space probe named New Horizons flew past Pluto and radioed back some incredible images of this distant world and its moons.

Skywatch 3-12-2021-PG1-SWFR.mp3

Fri Mar 12, 2021 ROBERT GODDARD’S ROCKET

Nearly a hundred years ago, the world’s first liquid-fueled rocket was launched, in Auburn, Massachusetts. The man who launched it was its inventor - Robert Goddard. Rockets had been around for a long time – the Chinese were using them eight hundred years ago. But all rockets up to March 16, 1926, were solid-fuel, using a kind of gunpowder as the propellant. The problem with those rockets was that once ignited, the rocket fuel continued to burn until it was used up – no off switch. With liquid fuel it was possible to start, stop, restart, throttle the engine up or down - in other words, liquid-fueled rockets were easier to control, and safer too. The folks in Massachusetts didn’t seem to appreciate this however, and he was branded a nuisance. And the New York Times back then said he was wrong, that rockets wouldn’t work in space. Evidently they were mistaken, because, thanks to Robert Goddard, we’ve sent rockets outward to the moon, to the planets, to the stars.