Mon Jun 27, 2022 HEBER CURTIS
150 years ago the American astronomer Heber Curtis was born on June 27th, 1872. He found strong evidence that the Milky Way was not alone. Novas, stars that periodically brighten and dim, were found among many spiral nebulas. Because they were very dim, he calculated that these novas were millions of light years away – too distant to be within the borders of our own galaxy. He was right! Curtis studied and photographed many nebulas and galaxies, discovered a jet of matter shooting out from the giant elliptical galaxy M87, (we now know it is powered by an enormous black hole at the galaxy’s core), and carefully observed nearly a dozen solar eclipses in his career. A deeply spiritual man, he declared, “The more I know of Astronomy, the more I believe in God.”
Tue Jun 28, 2022 TCAS MEET/CONSTELLATION SHOOTOUT
On Tuesday, June 28th, there will be a meeting of the Treasure Coast Astronomical Society at 7:30 pm at the Hallstrom Planetarium. This evening’s meeting will be a special one: several astronomy club members, well-acquainted with the stars in the sky, will have a competition known as a Constellation Shootout, which will determine who knows them the best. Contestants will take turns pointing out and naming the stars on the planetarium dome. If a contestant is right, he or she moves on to the next round. Get it wrong, and you’re out. The winners will receive prizes in the forms of some old astronomy textbooks I’ve been trying to get rid of for a while now, so everybody wins! The public is invited to attend this competition – again, tonight at 7:30, at Indian River State College’s Hallstrom Planetarium in Fort Pierce.
Wed Jun 29, 2022 ERATOSTHENES MEASURES THE EARTH
In late June, in the year 240 BC, the astronomer Eratosthenes calculated the size of the earth. He did it by using the changing angle of sunlight at different latitudes in Egypt. Eratosthenes made two assumptions: 1. the earth is round; 2. the sun is far away, so its rays fall parallel across the whole earth. At Alexandria, the sun is about 83 degrees, or 7.2 degrees off the zenith) at noon on the first day of summer. 500 miles to the south was a town called Syene, where on the same day, the sun’s image at noon could be seen reflecting off the water at the bottom of a deep well. There the sun was at 90 degrees altitude, directly overhead. The Alexandria - Syene distance must therefore be 7.2/360th, or a fiftieth of the earth’s circumference. Now Syene was 500 miles away, so he multiplied 500 by 50, and got 25,000 miles for an answer. He was off by a hundred miles – “pretty good work for 2,262 years ago!”*
*Carl Sagan quote from “Cosmos”
Thu Jun 30, 2022 TUNGUSKA
Several years ago, an early morning fireball lit up the sky over Chelyabinsk, Russia. Shock waves from the impact shattered windows, injuring over a thousand people. Now this was not the first time such a thing had happened. Back on June 30th, 1908, something really big blew up in the atmosphere above the Tunguska region in Siberia. Eyewitness reports sound a lot like the Chelyabinsk event. A brilliant blue light, like a second sun, flashed across the early morning sky. It was followed by a sonic shock wave that broke windows, killed wildlife, knocked people to the ground, and shook the earth. The Chelyabinsk impactor was a rock over fifty feet across, which broke apart about ten to 15 miles above the surface. The total energy of the blast was roughly equal to that of dozens of atomic bombs. The Tunguska blast was at least five hundred times more powerful.
Fri Jul 1, 2022 VEGA IN THE EAST – VULTUR CADENS
This evening, look toward the east. There’s a bright star over there – its name is Vega, and it’s the fifth brightest star in the night sky. Vega is from an old Arabic word meaning, “falling, (or “swooping,) eagle (or vulture)”. Vega is part of an ancient star pattern known as vultur cadens, which also means, “falling vulture,” although the official constellation here is Lyra, the Harp. On star charts you can sometimes see it pictured as a vulture with a harp inscribed within it. Above Vega are some fainter stars which trace out a simple letter H. The H stands for Hercules, and for his sixth labor, this mythical Greek hero shot arrows at this vulture, and also at two nearby constellations, Cygnus the Swan and Aquila the eagle, driving them away from Lake Stymphalus, where they had picked up the unfortunate habit of swooping down and attacking any unsuspecting people who wandered by.