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Skywatch for the week of April 12, 2021

Skywatch 4-12-2021.mp3

Mon Apr 12, 2021 YURI GAGARIN

Sixty years ago today, on April 12th, 1961, the first human was launched into space. What was his name? It wasn’t John Glenn, he was the first American to orbit the earth in a Mercury spacecraft. It wasn’t Neil Armstrong, he and Buzz Aldrin were the first astronauts to land on the moon, back in 1969. It wasn’t Alan Shepard. He also walked on the moon, and he was the first American to go into outer space, but that happened almost a month after the first man orbited the earth. That man was Yuri Gagarin, a Soviet cosmonaut. It was a smooth launch and a smooth orbit, but the way Gagarin came back to earth was a bit unorthodox. The Vostok spacecraft didn’t have enough parachutes to slow it down without leaving a small crater, so several miles up, Gagarin was ejected from the capsule, and then had to parachute down to the ground all on his own – those were exciting times!

Skywatch 4-13-2021.mp3


On April 13, 1842, the mirror for the Irish Leviathan was completed. It was six feet across, and was built by William Parsons, the Earl of Rosse, at Birr Castle in Ireland. The mirror was not made of glass, but of metal, an alloy of copper and tin. Upon completion and installation in the fifty-six foot-long telescope tube, the instrument was named the Irish Leviathan, and for the next seventy years, it was the biggest telescope on earth. Parsons observed stars, the moon, and the planet Jupiter. Then the potato famine hit Ireland, and the Leviathan was shut down. But in April of 1845, the telescope was running again and the Earl observed M51, a large nebula in the constellation Canes Venatici. He called it the Whirlpool, describing it as a "spiral nebula". Parsons even saw individual stars in the Whirlpool, and suggested it was a distant galaxy, similar to our own Milky Way. He was right.

Skywatch 4-14-2021.mp3


The Big Dipper is well-placed in the northeast sky after sunset, and it’s a helpful guide to other stars. If you draw a line through the two stars in the front of the Big Dipper's bowl and extend that line to the north, it will point to the North Star, Polaris, which is not really a very bright star at all, but it is always in the north, because the earth’s North Pole points toward that star. Polaris is also at the end of the handle of the Little Dipper, which is also hard to see since most its stars are even dimmer than Polaris. So go back to the Big Dipper’s pointer stars and run a line in the other direction, and you’ll discover a group of stars that looks like a backwards question mark high up in the eastern sky - that’s Leo the Lion. Finally, draw a line through the three stars in the Big Dipper’s handle, and then fly off the handle, and low in the east are the stars Arcturus and Spica.

Skywatch 4-15-2021.mp3

Thu Apr 15, 2021 EMPTY SPRING SKY

Some parts of the sky have more bright stars than others. The stars are fairly randomly distributed, but it seems as though most of the really bright ones can be found in the winter evening sky. The evening skies of summer have some bright stars, too, but the fall sky and the spring sky are relatively empty of bright stars. This spring there are a few exceptions – the star Regulus, the heart of the constellation Leo the Lion at the top of the sky, the stars Arcturus and Spica, in the east and the southeast this evening; and the planet Mars, which can be found near the western horizon. But this evening, most of the bright stars by far are actually holdovers from winter - brilliant Sirius and bright Procyon in the Greater and Lesser Dogs, Capella in Auriga the Charioteer, Castor and Pollux in Gemini, the Twins, plus Betelgeuse and Rigel and the belt stars of Orion the Hunter.

Skywatch 4-16-2021.mp3


Of the eighty-eight officially recognized constellations, can you identify the seventeenth largest one? It is bordered on the north by Auriga and Perseus, on the south by Eridanus, on the west by Aries, and on the east by Orion. Within its borders are such deep sky objects as the Crab nebula, the Hyades star cluster, and the better-known Pleiades, or Seven Sisters. This constellation’s brightest star is Aldebaran, a red giant forty times larger than the sun. One of the oldest star patterns, in mythology this animal is sometimes seen as a representation of Zeus, who carried the princess Europa across the sea to Crete; or as the seventh labor of Hercules. Tonight the waxing crescent moon and the planet Mars can also be found between its horns. Can you name this star figure, the second constellation of the zodiac? The answer is Taurus the Bull, currently visible in the western sky this evening.