Skywatch week of August 5, 2019
Tue Aug 6, 2019 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.)
Wed Aug 7, 2019 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.
Thu Aug 8, 2019 SCORPIUS – MAUI’S FISHOOK This evening the moon, a little past its first quarter phase, can be found at the head of the constellation Scorpius in the southern sky. The planet Jupiter is a little bit to its left, and tomorrow night these two worlds will appear even closer. Scorpius is one of the few constellations that looks like it should, outlining a scorpion from Greek myth. But to folks in the South Pacific, Scorpius was known as Maui’s fishhook. Maui and his brothers were far out at sea, when Maui’s fishing line suddenly went taut. He urged his brothers to row as hard as they could, and with all his strength, attempted to lift the mighty fish out of the ocean. But it wasn’t a fish; Maui had snagged the sea bottom. He pulled so hard that he brought the ocean floor up to the surface where it became the island of Hawaii. The great fishhook itself flew up into the sky, where everyone can see it tonight, a cosmic reminder of the big one that got away.
Fri Aug 9, 2019 THE “TEARS OF ST. LAWRENCE” Every year at this time, the earth travels through a portion of its orbit that is littered with bits of ice and dust left in the wake of a passing comet. As we plow into this region, we are treated to a display of shooting stars, as those particles plunge through our atmosphere. None of this debris strikes our planet, but vaporizes, lighting up the sky in a brief flash of light – a meteor. This particular meteor shower is called the Perseids, so named because they seem to come out of the part of the sky near the constellation Perseus; it’s a reliable shower viewed by millions of people for many years: in medieval times it was known as the “tears of St. Lawrence,” in honor of the Christian martyr whose feast day is tomorrow, August 10th. Grab a reclining lounge chair, protect yourself against mosquitoes, go out late in the evening or after midnight, face east, and look up toward the top of a clear, dark sky for the best views.