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Skywatch for the week of November 6, 2023

Skywatch Monday 11-6-2023.mp3

Mon Nov 6, 2023 FRED WHIPPLE

Fred Whipple was born on November 5th, 1906. He helped to plot the orbit of the newly discovered planet Pluto, and in the 1930’s he showed that meteor showers are the result of particles shed from passing comets. Whipple is best known for his work in comet theory: in 1950, he came up with the model for comet composition that is still in use today. It’s the “dirty snowball” theory, which proposes that comets are big chunks of ice, mostly water ice, with some rocks and dust mixed in. When a comet nears the sun, the ices melt or sublimate and form an atmosphere or coma, around the comet nucleus; the solar wind and the pressure of sunlight blow this atmosphere out into a long tail. When the Giotto spacecraft flew by Halley’s Comet and looked at it during the comet’s 1986 appearance it confirmed his theory.


Skywatch Monday 11-6-2023.mp3

Tue Nov 7, 2023 MESSIER’S FALL

Today was the beginning of a very bad year for Charles Messier. On November 6th, 1781, the French astronomer fell down a flight of stairs. It took him over a year to recover from his injuries, but then Messier got back to work, making successful observations of the planet Mercury and then going on to discover over a dozen comets in his career. He also made a list of deep sky objects that still bear his catalog numbers, all beginning with the letter M – M, for Messier. There’s M1, the Crab Nebula, which marks the spot where a star exploded a thousand years ago; or M13, a globular star cluster in Hercules; or the Great Orion Nebula, M42. Then there’s M31 – the Andromeda Galaxy! Messier also managed to survive the French revolution and subsequent reign of terror, and was awarded the Cross of the Legion of Honor in 1806 by the Emperor Napoleon.


Skywatch Wednesday11-8-2023.mp3


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.


Skywatch Thursday 11-9-2023.mp3


If you go out long after midnight tonight - say an hour or so before sunrise – you should be able to see the moon and the planet Venus together in the heavens, what astronomers call a conjunction. If the skies are not cloudy, you’ll be able to find the moon, a thin waning crescent with its bow aimed downwards toward the east horizon. Right next to the moon, there will be a brilliant star, which is actually the planet Venus. It will look like the two are almost touching, but of course that’s an illusion. The moon is about two hundred and forty thousand miles away, but Venus is tens of millions of miles farther out. Conjunction. are fairly common, but they sure are pretty! While the lower limb of the moon is lit up directly by the sun, you should still be able to see its entire disc, something called, “the new moon in the old moon’s arms.”


Skywatch Friday 11-10-2023.mp3


I remember my 8th grade science teacher telling us that Star Trek was unrealistic because every time the starship Enterprise sailed by during the opening credits, it would go, “whoosh!” And that was wrong, because there is no air in space to make any kind of sound at all. Now it’s true that sound waves need a transmitting medium to be heard. But what if outer space did have a transmitting medium? When robotic spacecraft passed Jupiter and Saturn, the emissions from their magnetospheres were converted into sound, making a very eerie kind of “music.” NASA calls this, “data sonification.” Likewise, if a spacecraft flies through a particle field, like Saturn’s ring system, or through the dust tail of a comet, the sounds of those mini collisions are “heard,” and transmitted back to earth. This is the true, “music of the spheres!”