Skywatch for the week of August 2, 2021
Mon Aug 2, 2021 LUGHNASADH - LAMMAS
Yesterday was the third cross-quarter day of the year: this time it’s Lammas, which neatly divides the summer season into two halves. The old name for today was Lughnasadh, commemorating the marriage of the Celtic sun god Lugh to Danu the earth goddess, assuring that the crops would grow and ripen. Their children became the Tuatha de Danaan, the fairy folk of Ireland. In the Christian reckoning, this was the “Loaf Mass,” which eventually became called, “Lammas.” The loaves of bread baked at this time were consecrated as the first harvest food, what was called, “the feast of first fruits.” Not that long ago, many folk lived in a farm or country setting. This was an extraordinarily busy time, because first, there was a lot of farming to be done; and second, the days were still very long which meant the workday just kept going until everyone was exhausted. Lammas was a small break in this work, work, work period – a chance for everyone to bake some bread and give thanks for the respite.
Tue Aug 3, 2021 MARIA MITCHELL
The first American woman astronomer, Maria Mitchell, was born on August 1st in the year 1818. She learned astronomy from her father William Mitchell; as a young girl she helped him in his observatory on Nantucket Island. And on October 1st, 1847 she set up a telescope on her parent’s housetop and discovered a comet. The next year she became the first woman member of the American Academy of Arts and Sciences. She also served as professor of astronomy at Vassar College from 1865 until a year before her death in 1889. She contributed to the American Nautical Almanac, observed sunspots and solar eclipses, plus the planets and the moon. A crater on the moon is named for her. Maria Mitchell said, “We especially need imagination in science. It is not all mathematics, nor all logic, but is somewhat beauty and poetry.” But she also asked of her students, "Did you learn that from a book or did you observe it yourself?"
Wed Aug 4, 2021 STARING AT THE SUN – DON’T!
The brightest object in the sky is the sun - so bright, in fact, that it's difficult to look anywhere near it because of its blinding brilliance. One rumor often heard is that the Italian astronomer Galileo went blind from viewing the sun through a telescope, but it’s not true: he used his telescope only to project the sun’s image onto a viewing surface, which is perfectly safe. Long before the invention of the telescope, ancient Greeks observed and described large sunspots, perhaps 40,000 miles across that sometimes appeared on its face. They did this by watching the sun only while it was rising or setting, and at its dimmest. As you may have guessed, this is definitely NOT a safe practice: even though the amount of visible light is cut down by the thick column of air at the earth's horizon, the sun is still emitting invisible radiation which can blind you. So never stare at the sun, even at the beginning or end of the day.
Thu Aug 5, 2021 QUASAR DISCOVERY
The first quasar was discovered on August 5th, 1962. It has the unromantic designation, 3C273, the 273rd object in the third Cambridge catalog of radio sources. Quasi-stellar radio sources, or quasars, are so faint they can only be seen by powerful telescopes. They look like stars, but quasars emit a lot of energy in other wavelengths of light invisible to the human eye. They’re dim because they’re really far away! 3C273 actually puts out more energy than the combined light of the hundreds of billions of stars of our entire Milky Way, and this from an object only the size of our solar system! We think quasars are the hearts of galaxies that formed when the universe was young; these powerful light sources no longer exist. 3C273 is in our southwestern sky this evening, not too far from the bright star Spica in the constellation Virgo,(but several billion light years farther out of course.)
Fri Aug 6, 2021 GALILEO’S FIRST TELESCOPE
On August 8th in the year 1609, members of the Venetian senate climbed to the top of the tower of St. Mark’s Cathedral for a demonstration of Galileo’s first telescope. The senators viewed ships far out at sea, ships that couldn’t be seen by the naked eye for another two hours. What a marvelous invention! Galileo’s salary as professor of mathematics at the University of Padua was immediately doubled. Now if you were to buy today the cheapest, crummiest telescope you could find, it would still be vastly superior to that first one. Galileo did not invent the telescope; he had simply been told about telescopes built by others, and made one of his own based on the reports. But it was what he did with the telescope that made the difference. Instead of looking at ships out at sea, he turned the telescope skyward, and wrote about the moon, the planets and the stars - all the marvelous sights visible in the heavens.