Mon Jul 15, 2019 PRINCIPIA
On July 6 in the year 1686, Principia Mathematica was published in England. Principia was Isaac Newton’s great book on gravity and motion, which became a major breakthrough for our understanding of how the Universe works. His three laws of motion – inertia; force equals mass times acceleration; and action-reaction, plus the relationship between gravity, mass and distance, are still in use today, showing us how we can send rockets to the moon and beyond. Kind of a shame he didn’t pay for the printing of his own book. Edmond Halley paid for its publishing, because he wanted it to help him work out comet orbits. Halley tried to get the Royal Society to pay for it, but they’d tied up all their money in a beautiful book, the History of Fishes, which they weren’t able to sell. Years later, when Halley wanted payment for his duties as secretary, they just gave him a lot of the fish books and suggested he could sell them and make some money that way.
Tue Jul 16, 2019 JULY FULL MOON/APOLLO 11 LAUNCH
The moon is full. Because thunderstorms are common in July, this full moon is often called the Thunder moon. According to the Sioux Indians, this is the Moon When the Wild Cherries Are Ripe. To the Winnebago, it is the Corn-Ripening Moon, and to the Kiowas (kye’ e wah), it is the Moon of Deer Horns Dropping Off. To the Omaha Indians, however, this is the Moon When the Buffalo Bellow. In ancient China, this was the Hungry Ghost Moon, named for departed souls who had left no descendants; and in medieval Europe this was the Hay Moon or the Mead Moon, named for the elixir from the meadows of summer. Fifty years ago today, a Saturn 5 rocket, with astronauts Mike Collins, Neil Armstrong and Buzz Aldrin on board, was launched to the moon. The moon’s phase that day was a thin waxing crescent; by the time the Apollo 11 spaceship reached the moon over three days later, the sun was just rising on the Sea of Tranquility, allowing for a safe landing at the beginning of the lunar day.
Wed Jul 17, 2019 LOOK-BACK TIME
If you can manage to live for 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 calculation comes from data collected by the Hipparcos satellite; some of my colleagues insist that Alkaid is really 104 light years away, so you may want to hang on a few more years just in case.) 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!
Thu Jul 18, 2019 STARS OF THE SUMMER TRIANGLE
The Summer Triangle is made up of three bright stars that are well-placed in the eastern sky after sunset at this time of the year. The highest star, Vega, is the brightest of the three, but the star Altair, below and a little to the south of Vega, is almost as bright. The third star, the northernmost one, is called Deneb, and it’s no match for the brightnesses of the other two. But that’s because, as you may have guessed, Deneb is much farther away from us, so its light is correspondingly dimmer. Altair is a mere seventeen light years away – that’s a little over a hundred trillion miles. Vega is a little farther away, twenty-five light years, but it’s an intrinsically brighter star, and that extra luminosity makes it brighter. But Deneb, which is the dimmest star, is also about a hundred times more distant; if Deneb were as close to us as the other two, it would be bright enough to cast shadows!
Fri Jul 19, 2019 APOLLO 11 LANDING ANNIVERSARY
Fifty years ago today, astronauts Neil Armstrong and Buzz Aldrin and Mike Collins were orbiting the moon. They were not its first visitors: six men had preceded them, in Apollo’s 8 and 10; but those astronauts never landed. When the lunar lander Eagle separated from the Apollo command ship Columbia, Aldrin and Armstrong piloted it down to the moon’s surface, and on July 20th, 1969, at 4:18 pm they landed on the southern edge of Mare Tranquilitatis, the Sea of Tranquility – a huge lava flow of dark basaltic rock. At 10:56 pm, Neil Armstrong stepped onto the lunar surface, followed by Buzz Aldrin about ten minutes later. Tonight and tomorrow night, Indian River State College’s Hallstrom Planetarium will be open, from 6 – 9 pm, to recognize this achievement. We’ll watch the Apollo films and reminisce about the landing, and the Treasure Coast Astronomical Society will provide telescope views of Jupiter and Saturn, weather permitting. This event is free.
