Mon Jul 22, 2024 LOOK-BACK TIME
If you can manage to live a full century, go outside at night on your 101st birthday and look at the star at the end of the handle of the Big Dipper, in the northwest this evening. The light from that star, Alkaid, left there the day you were born – this distance measurement comes from the Hipparcos space satellite. Now go farther out: in the south is the star Antares, 500 light years away. If it went supernova today, we wouldn’t know about it for another 500 years. It takes light time to travel across the Universe. This phenomenon, Look Back Time, means that the farther something is from us, the older it is. So when we look at the Andromeda Galaxy, 2.5 million light years away, it’s what that galaxy looked like 2 and a half million years ago. What does it look like now? Not sure, but I’ll know, in about 2 and a half million years!
Tue Jul 23, 2024 THOMAS HARRIOT BEATS GALILEO
Toward the end of July in the year 1609, the Englishman Thomas Harriot made the first detailed drawings of the moon as seen through a telescope. Galileo would make his drawings several months later, not quite as good as Harriot’s, but while Galileo became famous, hardly anyone has ever heard of Harriot. Galileo published his discoveries in a widely read book, The Starry Messenger. Harriot wrote manuscripts, but never published a book for public consumption. Harriot led an interesting life, accompanying Sir Walter Raleigh to the Roanoke colony in America, serving as mathematician, navigator and interpreter. He was briefly imprisoned in 1605 on account of suspicions that he had been part of the assassination attempt on King James 1. He was innocent and released, but this may have made him less eager to publish, not wishing to draw attention to himself.
Wed Jul 24, 2024 APOLLO 11 LANDING ANNIVERSARY
On July 20th 1969 at 4:18 pm Eastern Daylight Time, Apollo astronauts Neil Armstrong and Buzz Aldrin, aboard their lunar spacecraft Eagle, touched down on the moon, landing on a basaltic rock lava basin called the Sea of Tranquility. At 10:56 pm, Neil Armstrong stepped onto the lunar surface, followed by Buzz Aldrin about ten minutes later. They were outside for two-and-a-half hours, setting up several lunar science experiments and collecting about fifty pounds of moon rocks. Shortly before 2 pm Eastern Daylight Time on July 21st, they blasted off from the moon and rejoined Command module pilot Mike Collins who was on board the Columbia spacecraft in lunar orbit. All three came back to earth on July 24th fifty-five years ago today. The last time anyone walked on the moon was back in 1972; when will we return?
Thu Jul 25, 2024 THE DOG DAYS
These are the "dog days" of summer. The sun was highest in our noon sky on June 21st, but it takes the air a month to really sizzle. These are called the dog days because it's at this time of the year that you can first catch sight of the brilliant star Sirius, also known as the Dog Star, low in the southeast, rising just before the sun. Sirius is the brightest star in the night sky, partly because it’s a big, hot star, but mainly because it’s closer to us than most other stars, only about 54 trillion miles away! Its name is from the Greek word, "seirios," which means, “the scorcher.” Sirius is in the constellation Canis Major, the Big Dog, and that’s why it’s called the Dog Star. Sirius was feared and hated by the ancient Greeks and the Romans, who thought that when the sun and Sirius got together, their combined heat burned up the crops, drove dogs mad, and made everybody miserably hot.
Thu Jul 25 Sky Report on WPSL: Dog Days of Summer – heliacal rising of Sirius.
Fri Jul 26, 2024 THE MILKY WAY AND THE LOCAL GROUP
The Milky Way, part of it at least, can be seen tonight under clear dark skies. It spreads across the eastern sky, from Cassiopeia in the north to Sagittarius in the south. The Milky Way is our home galaxy; we live on a planet orbiting a star about two-thirds of the way out from its center. We have satellite galaxies, most notably the Large and Small Magellanic Clouds. And there’s a bigger spiral galaxy about 2 and a half million light years away: its catalog number is M31, but we know it best as the Andromeda Galaxy. Now besides the Milky Way and M31, there are about 30 other, smaller galaxies in the immediate neighborhood (and by “immediate neighborhood,” we mean anything that’s within a million parsecs of here.) This cluster of galaxies is called the Local Group. Most of them are fairly small and contain only a billion or so stars. M31 and the Milky Way are the Group’s gravitational “anchors”.
