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Skywatch for the week of October 23, 2023

Skywatch Monday 10-23-2023.mp3

Mon Oct 23, 2023 HOW MANY STARS?

How many stars are there? on a clear dark night you can see a couple thousand. The best estimates of the number of stars in the Milky Way suggest there are over 300 billion stars. Beyond the Milky Way other galaxies, hundreds of billions of them, contain trillions of stars. So, how many stars? Here’s a good way to get an idea. Next time you’re at the beach, count the number of grains of sand you can hold in your hand. You’ll be at it a while; there’s roughly 10,000 sand grains in each handful. Now count all the grains of sand on the entire beach. Follow that up by counting all the grains of sand on all the beaches of Florida, and then for extra credit, count all the grains of sand on all the beaches of the world. There are more stars than that in our Universe.




The moon is now in its waxing gibbous phase; when you see it early this evening, it will look lopsided, like an egg in the sky. As twilight gives way to night, you should be able to find a fairly bright, slightly yellowish star just slightly to the west of the moon. That star is actually the planet Saturn. Whenever two celestial objects appear near each other in the sky, it’s called a conjunction, and conjunctions are fairly common. Once each month, the moon completes a full orbit of the earth, and so appears against a different background of stars and planets as the days and nights progress. Tonight it’s Saturn’s turn. Both the moon and Saturn can be found among the stars of the zodiacal constellations Capricornus and Aquarius. Tomorrow night the moon will be a full hand-width to the east of Saturn.


Skywatch Wednesday10-25-2023.mp3

Wed Oct 25, 2023 DEATH OF TYCHO

“Let me not seem to have lived in vain.” These were the last words of the Danish astronomer Tycho Brahe, who after eleven bed-ridden days of suffering, died on October 24, 1601. Working before telescopes were invented, Tycho accurately measured star and planet positions and proved that comets were well beyond the earth. Tycho was at a banquet, and did not wish to insult his host by leaving early. As a result, his bladder burst, which killed him. In 1993, Brahe’s body was exhumed, and analysis of his hair seemed to show a lot of mercury; as an alchemist, had he accidentally poisoned himself? But a more recent autopsy shows that his mercury levels were almost in the normal range, supporting the opinion of the doctor who attended the astronomer as he lay dying; Tycho may actually have died from a burst bladder.


Skywatch Friday 10-27-2023.mp3


Indian River State College recently held a “brain bowl,” where our students compete, answering questions on math, science and the humanities. In honor of the brain bowl, here’s a quiz for you: Where is the Sea of Serenity? What is Newton’s Third Law of Motion? What’s the tallest volcano in the solar system? Which star is closest to earth? What is New Horizons? Here are the answers: The Sea of Serenity is a dry lava basin on the moon. Newton’s Third Law states that for every action there is an equal and opposite reaction. The tallest volcano is fifteen-mile-high Mt. Olympus on Mars. The nearest star after the sun is Proxima, part of the Alpha Centauri system, 25 trillion miles away. And New Horizons is a spacecraft that was launched toward Pluto; it reached this distant world eight years ago and sent back incredible images of Pluto and its moons.


Skywatch Friday 10-27-2023.mp3


The moon will be full this weekend. Last month we had the Harvest Moon, tomorrow we will have the Hunter’s Moon; long ago the light of this full moon was useful when one had to pursue dinner in the dark. This is also the Sioux Indians’ Moon of Falling Leaves; the Big Wind Moon of the Zuni tribes; or the Cheyenne’s Moon When the Water Begins to Freeze on the edge of the Stream - must be getting cold up north. The Ponca Indians, in observance of the time when food is harvested for the winter, call this the Moon When They Store Food in Caches, while the Kiowa simply call it the Ten Colds Moon, a harbinger of the freezing weather that follows. October’s full moon was also called the blood moon in medieval England, a reference to the reddish coloring often displayed by the rising full moon of October.