Mon Nov 10, 2025 EDMUND HALLEY’S BIRTHDAY
Edmund Halley, whose name is attached to a very famous comet, was born on November 8th, 1656 near London. Halley saw his comet in 1682, and although millions of people had seen it before him, going back to BC times, he was the first person to predict its return, in 1758. Halley had asked Isaac Newton to write the equations he needed to solve the comet’s orbit, (Newton had to invent calculus to do it,) and using Newton’s work, Halley figured out it would return in 76 years, saying that he hoped that posterity would record that an Englishman had made the prediction. Now if you missed seeing the last appearance of Halley’s Comet in 1986, then you’ll want to hang around for its next apparition in the year 2061. I’ll be 108, and I’m looking forward to seeing it again.
Tue Nov 11, 2025 SELENOLOGY
The moon is about a fourth of the diameter of the Earth. Technically, it doesn’t revolve about us, but about a common center of gravity knowns as a barycenter, that happens to lie about a thousand miles below the surface of the Earth. The Earth and the moon have a lot of common characteristics, but also quite a few differences. The Earth is somewhat denser, containing more metals for instance. The composition of earth rocks and moon rocks is similar, but the mineral content is slightly different and moon rocks are amazingly dry! The study of the moon and its geology and landforms is called selenology – Selene is a very old name for the moon; in Greek mythology she was the sister of the old sun god Helios.
Wed Nov 12, 2025 WILLIAM HERSCHEL BORN
William Herschel was born on November 15th, 1738. Herschel was a church organist in Bath, England. He also had a great interest in astronomy, and in telescopes. But most musicians don’t make much money, and telescopes were expensive. So he built his own. It was with just such a telescope that in March of 1781, William Herschel discovered a planet. Herschel named it George, after the King of England. Many astronomers suggested the planet simply be called, Herschel. Eventually Uranus, who in mythology was the father of Saturn, was chosen. Herschel also found four moons: Oberon and Titania, which orbit Uranus, and Mimas and Enceladus, which orbit Saturn. And Herschel mapped the stars of the Milky Way, concluding from their distribution that the galaxy in which we live was shaped like a giant disc.
Thu Nov 13, 2025 TYCHO’S COMET
On November 13th, 1577, the Danish astronomer Tycho Brahe observed a comet and discovered that they exist far out in space (previously it was thought that comets were created in the atmosphere.) Brahe used parallax to prove this.Hold your thumb up at arm's length, and look at it with first one eye, and then the other, and you'll see your thumb jumps back and forth against the background.If you bring your thumb in closer, the parallax shift increases. Brahe noted the comet’s position against the background stars and compared his measurements with other astronomers and found that the comet’s parallax was less than the moon's, therefore farther away. Comets Swan and Lemmon are in our sky now, but they’re pretty faint. We haven’t seen a really bright comet since Comet Hale-Bopp, which a lot of people saw back in 1997.
Fri Nov 14, 2025 LEONIDS
The Leonid meteor shower reaches peak activity over the next couple of nights. The Leonids, so-called because these meteors seem to come from the direction of the constellation Leo the Lion, have been in a bit of a decline lately, but they’re still worth going out to see. As a rule, meteor showers are best after midnight, but if that’s too late, go outside during the late evening hours. Protect yourself against mosquitoes, dress warmly, take along a lounge chair for comfort, find a clear, dark sky and face east, looking up toward the zenith. You should be able to see several meteors an hour, but there can be stretches of ten or fifteen minutes sometimes, when nothing happens. So sit back and enjoy the starry night sky.
