Skywatch for the week of October 4, 2021
Mon Oct 4, 2021 SPUTNIK, SATELLITES
On October 4, 1957, the world’s first artificial satellite, Sputnik, was sent into earth orbit from a launch site in the Soviet Union. A few months later, the United States successfully launched Explorer 1, and another satellite now revolved about the earth. Today, there are thousands of satellites in orbit; and every so often, you can see one passing overhead. It looks like a moving star, or like a light from a high-flying jet, but the satellite moves along at a pretty good clip, crossing the sky in only a matter of minutes, and yet you can't hear any sound coming from it. These satellites reflect sunlight down to the darkened earth, and so are visible for a couple of hours after sunset or a couple of hours before sunrise, a time when we are in earth's shadow, but the satellite is just outside it. Satellites typically travel from west to east, except for those in polar orbits which move along a north-south path.
Tue Oct 5, 2021 ROBERT GODDARD
Dr. Robert Goddard, the father of rocketry, was born on October 5th, 1882. When he suggested that rockets could take us to the moon, the New York Times announced that he was wrong, because everyone knew that rockets couldn’t work in outer space because there was no air for them to push against. But Goddard understood that a rocket’s exhaust did not push against the air; the action of the combustion in the rocket created the reaction of the exhaust pushing against the rocket itself (Newton’s Third Law.) In fact, rockets work even better in the vacuum of space than in atmosphere, as there’s no air to have to push out of the way. In 1926 he launched the first liquid-fueled rocket (before this, all rockets relied on solid, gunpowder-style-fueled propulsion.) The problem with solid-fuel rockets is that once you light them, they go until they run out of fuel. The advantage of liquid fuel is that you can throttle back the engines and obtain a great deal more control over the flight of the rocket.
Wed Oct 6, 2021 NEW MOON SYNOD
As a college student, I once auditioned for one of the theater department’s plays – Shakespeare’s “Comedy of Errors.” I didn’t get the part I wanted, that of the Duke, which was kind of a shame since I had memorized his lines, part of which went something like this: “For, since the mortal and intestine jars 'Twixt thy seditious countrymen and us, It hath in solemn synods been decreed, To admit no traffic to our adverse towns.” So then you have to ask yourself, what the heck is a solemn synod? For that matter what’s a synod, solemn or otherwise? It’s a meeting, usually a religious council, but also a civil meeting, that’s held at a pre-arranged time, say during a new or a full moon. Today there is a new moon, and if we were using a lunar calendar, today would mark the first day of the month. The synodic month then, is a period of time marked by a complete cycle of moon phases, which is 29 and a half days in length.
Thu Oct 7,2021 THE END OF THE WORLD
The astronomer Harlow Shapley once suggested two possible ways that the world could end. In one scenario, the earth loses its forward momentum, and the sun’s gravity pulls our planet inward to a fiery destruction. Another theory supposed the opposite might happen, that the earth might drift outward and suffer a frozen death like Mars. Of course, both “fire and ice,” may be our ultimate fate. Five billion years from now, when the sun runs out of fuel, gravity will take over and collapse it. This will heat it up, and the sun will expand to become a red giant star, engulfing the inner solar system, including earth. Then, when the last bit of helium fuel is exhausted, the sun will collapse again, heating up, turning into a high energy white dwarf! But then, after a great long time, it will cool off to become a black dwarf. What’s left of the earth will continue to circle the dying sun in a dark, cold orbit. So, let’s make it a point, five billion years from now, to get off the planet!
Fri Oct 8, 2021 NAME THAT CONSTELLATION - OCTOBER
Can you identify the thirty-third largest constellation? It is bordered on the north by Ophiuchus the Serpent Bearer, on the south by Lupus the Wolf, Norma the Level and Ara the Altar, on the west by Libra the Scales, and on the east by Sagittarius and the Southern Crown. Its tail dips into the Milky Way, and there are many nebulae and star clusters within its borders. This constellation’s brightest star is Antares, a red giant hundreds of times larger than the sun. In the South Pacific it’s called Maui’s fishhook, while old Greek myths identified it as the animal that killed the hero Orion the Hunter, but it is kept in check by Sagittarius’ arrows. Just a few thousand years ago the Romans turned its claws into Libra the Scales. Tonight the crescent moon appears to the west of it and the brilliant planet Venus shines out from its head. Can you name this star figure, the eighth constellation of the zodiac? The answer is Scorpius, currently visible in the southwestern sky after sunset.