Mon Jan 16, 2023 CALENDAR ORIGINS
Our calendar is based on repeating patterns in the heavens – the earth’s rotation, the phases of the moon, the earth’s orbit about the sun. The calendar has its origins thousands of years ago, from Egypt. By observing the sun’s progress through the sky, ancient Egyptians were able to accurately measure the length of the year, and knew it was about 365 and a quarter days long. Their calendar had 12 months of 30 days each, which worked out to 360 days total. Then they had five extra days or “empty” days, known as heiru renpet, which they used as a holiday at the end of the year. The new year began with the predawn rising of a star they named Sothis, which appeared in the east just before sunrise. Sothis is still shining up there; we call it Sirius, the brightest star in the night, which appears below and to the left of the constellation Orion.
Tue Jan 17, 2023 THE GREAT ORION NEBULA
A medium-power telescope can show you four tiny-looking stars buried within the Great Orion Nebula. These stars arranged in the geometric form of a trapezoid, are called the Trapezium. The brightest of these stars lights up the cloud, and ultraviolet radiation ionizes the nebula gas, illuminating it like a giant neon sign. The gas is mainly hydrogen and helium, but it contains a whole chemistry set of elements and compounds in smaller amounts too. The Orion Nebula is about 1300 light years, or 7,800 trillion miles away. So it’s not exactly next door. The cloud is trillions of miles across, and inside it, stars are being made as gravitational contraction heats the hydrogen and helium in the cloud. With the Hubble Space Telescope, we can even see places where solar systems are forming.
Wed Jan 18, 2023 EDGAR ALLAN POE AND THE EVENING STAR
The American writer Edgar Allan Poe was born on January 18, 1809. Some of his stories, such as, “The Tell-Tale Heart,” “The Raven,” and “The Pit and the Pendulum,” have even been made into movies. But in 1848, Poe wrote something called, Eureka, in which he discussed astronomy and the universe. While Poe was no professional astronomer, he kept up with the latest discoveries and theories, and in Eureka he suggests that the Universe is expanding, which was confirmed over 70 years after his death. And in his poem, Evening Star, he compares what he considered to be the cold, heartless light of the moon to the warm light of Venus, which even now appears above the western horizon in the evening twilight.
Thu Jan 19, 2023 JOHANNE BODE AND BODE’S LAW
Johanne Bode was born on January 19, 1747. In 1772 he advanced a mathematical theory which suggested the presence of additional planets, beyond the seven that were known of at that time. Start at zero, then skip to 3, then 6, and now keep on doubling the number. Then add 4 to each of those numbers and finally, divide by ten, giving you .4, .7, 1, 1.6, 2.4, 4.8, and 9.6. Those are roughly the spacings between the planets, expressed as astronomical units, the average earth-sun distance. This theory, called Bode’s Law, doesn’t work every time, and it’s not particularly exact, but it did point to a gap between the orbits of Mars and Jupiter. Astronomers began their search, and on January 1st, 1801, the Sicilian astronomer Father Giuseppe Piazzi used a telescope to discover the large asteroid we now call Ceres.
Fri Jan 20, 2023 THE PLEIADES
Near the top of the sky this early evening, you’ll find a small, distinctive group of stars known as the Seven Sisters. Even with street lights shining, you can find them, although the serious light pollution problems we experience here reduces the Seven Sisters down to just two or three, or possibly they may look like a little smudge overhead. But if you can get away from the bright lights, you’ll see between six to eight stars here, arranged in a very tiny dipper shape. In Greek mythology, the Seven Sisters were the Pleiades, the daughters of Atlas, on whose shoulders the world rested. Binoculars aimed at the Pleiades will reveal over a dozen stars, and astronomers have counted hundreds of stars in this open cluster.
