Skywatch week of August 19, 2019
Mon Aug 19, 2019 HELIUM DISCOVERED; SOLAR SAFETY
On August 18, 1868, a new element was discovered – and it was found in the sun! During a total solar eclipse, astronomer Pierre Janssen used a spectroscope to break up visible light into its component colors, kind of like a prism, but with much more detail. In the sun’s spectrum he saw a series of dark absorption lines that had never been seen before. Janssen had found a new element. It was named after Helios, the Greek sun god. That’s right, helium was discovered in the sun before it was ever found on earth, which makes sense, as helium is so light that unless it’s trapped underground or contained in a balloon, it leaks out through the atmosphere into space! A word of caution: don’t stare at the sun as it can blind you. Only with proper solar filters, or during the brief moments of totality of a solar eclipse is it safe to view the sun; and if you never leave the United States, you won’t see a total solar eclipse until the year 2024.
Tue Aug 20, 2019 EGYPTIAN CONSTELLATIONS
Many of the constellations we see now were also recognized by ancient Egyptians, but there were also many star patterns which were theirs alone. The Big Dipper, part of the larger constellation of Ursa Major, the Great Bear, was seen by the Egyptians as the leg of a great bull, a dismembered piece of the god Set. At the end of the handle of the Little Dipper, the star Polaris represented the coffin of Osiris, that diabolical death-trap, created by his brother Set for the express purpose of killing Osiris. The rest of the Little Dipper was sometimes a scorpion, or sometimes a jackal, the “dark and loathsome creature of Set.” Between the dippers is the long, straggling constellation of Draco the Dragon, seen in Babylonia as the frightful Tiamat, whose body was divided to make heaven and earth. But to the pharaohs of Egypt these stars also represented Taweret the Hippopotamus and Sobek the Alligator.
Wed Aug 21, 2019 MARDUK BRINGS ORDER OUT OF CHAOS
A very old story about how the Universe got its start comes from ancient Babylonia. It began with the watery chaos, known as Mammu. Out of Mammu came a monstrous dragon named Tiamat. Tiamat then spawned the Babylonian gods, but in time she came to hate them and decided to destroy them. But her grandson Marduk fought and defeated her. He used her body to serve as a framework for the cosmos. Half of her became the sky, where Marduk set the god Anu; the other half was made into the foundations of the earth, and Marduk made Ea its god. Marduk became the principle sky god, like Zeus in ancient Greece, and gave other gods responsibilities for the southern and northern skies and their constellations, while Marduk reserved the planets and stars of the zodiac for himself. And old Tiamat? You can see a vestige of her in the constellation Draco the Dragon, winding between the Big and Little Dippers tonight.
Thu Aug 22, 2019 RAY BRADBURY AND MARS
The science fiction and fantasy writer Ray Bradbury was born on August 22nd, 1920. He began his career by writing short stories for pulp magazines such as Weird Tales, Planet Stories and Galaxy Science Fiction. He also wrote, “Fahrenheit 451,” “R is for Rocket,” and “The Golden Apples of the Sun.” His book, “The Martian Chronicles,” came out in 1950; it was a series of related short stories about the colonization of the planet Mars, something which is very much in the news these days. Bradbury envisioned terraforming Mars, also being discussed lately. While building pressure domes and living underground on Mars is perhaps achievable, trying to restore a viable Martian atmosphere is still well beyond our current technology, and at the moment, Mars itself is also out of sight, as it’s behind the sun, on the opposite side of the solar system from where we are now. Well, like Bradbury, we can dream!
Fri Aug 23, 2019 HOW TO SEE A BLACK HOLE
In the sky this evening are three bright stars high overhead which are known as the Summer Triangle. Inside this triangle, in the neck of the constellation Cygnus the Swan, there is a great mystery - something which is invisible to the eye, but which nevertheless can be detected by the astronomer - that enigmatic phenomenon known as a black hole. It is called Cygnus X-1, and we can't see it directly because its gravity field is so intense that light can't escape it. But we know that it is there, because we've discovered an incredible amount of x-rays pouring out of this part of the sky. Cygnus X-1 is part of a binary star system. Gas from its companion, a massive blue giant, is being pulled from it to feed the accretion disc surrounding the hole; it’s here that the x-rays are being made, just outside the black hole's event horizon - its point of no return, about 2500 parsecs, or a little less than 48 quadrillion miles from Earth.