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Skywatch for the week of May 13,2024

Skywatch Monday 5-13-2024.mp3


Can you identify the thirtieth largest constellation? It is bordered on the north by Lynx and Auriga; on the east by Cancer; on the south by Canis Minor and Monoceros; and on the west by Orion and Taurus. In ancient Italy, it represented Romulus and Remus, the founders of Rome. The Navajo call its two brightest stars “the Place of Decision,” where the hero Long Sash and his people chose to follow the Milky Way up into the sky country. But we know these stars as Castor and Pollux, and tonight the waxing crescent moon appears to the east of them. Can you name this star pattern, the third constellation of the zodiac? It is of course, the Gemini, visible in the southwestern sky after sunset.


Skywatch Tuesday 5-14-2024.mp3


On May 11th, 1916, Albert Einstein's General Theory of Relativity was announced. It supplemented his earlier work on "special relativity", which stated that light travels at the same speed, whether you are moving toward the source of the light, or away from it. With general relativity, Einstein suggested that space itself is curved, the amount of curvature depending on the gravity fields of massive objects like stars and galaxies. Planets don't follow orbits because the sun is pulling on them; rather, they revolve because the sun's mass makes a big dent in the fabric of space-time, and the planets travel like marbles rolling on the inside of a funnel. Our sun’s gravity field is so great that the positions of distant stars are shifted by it. It's all pretty deep.


Skywatch Wednesday 5-15-2024.mp3


In the eastern sky this evening there is a star that doesn’t belong here – an intruder. It’s Arcturus, the fourth brightest star in our night sky. Most of the stars you see are moving along with our sun, traveling in nearly circular orbits about the hub of our Milky Way galaxy, but Arcturus, an old red giant star, moves at a sharp angle to all the others, plunging along an elliptical path through the disc from up above. Tonight, it’s a mere 37 light years away, that’s a bit more than 200 trillion miles, but in a half million years or so it will have shot down below us, and its ever-increasing distance will make it too dim to see without a telescope. So, enjoy viewing Arcturus while it’s still in the neighborhood!


Skywatch Tuesday 5-14-2024.mp3

Thu May 16, 2024 BERENICE'S HAIR

In the northern sky this evening the faint constellation of Coma Berenices appears to the south of the dipper’s handle. Berenice was the wife of one of the Ptolemies who ruled Egypt. Just before a great battle, Berenice promised to cut off her hair and place it in the temple as a sacrifice if Ptolemy survived. He did, and she did. Then somebody stole the hair – yes, a classic case of hair today and gone tomorrow! This got Ptolemy’s dander up! He ordered his soldiers to comb the palace until they found the hair. Some tried to give him the brush-off, but the head priest made up a bald-faced lie: he pointed to this part of the sky and declared that Berenice’s hair had risen up to the heavens to commemorate the occasion. As a result, Berenice's Hair is now a permanent constellation, all because of some great hair-raising battle of long ago.


Skywatch Wednesday 5-15-2024.mp3


Over the course of a year, the sun drifts eastward against the background of stars. It’s a very slow motion caused not by earth’s rotation, but by its revolution about the sun, which displaces the sun’s position by about 1 degree of angle a day – that’s less than the width of your little finger at arm’s length! After roughly 365 days, the sun returns to where it had been exactly a year ago. Today the sun appears below the Pleiades star cluster in the constellation Taurus. Next month it will be in Gemini, the month after that in Cancer, then Leo, and so on until next May 17th, when it will be alongside the Pleiades again. This defines the solar year as the amount of time needed for the sun to go full circle, once around the zodiac in the heavens.