Skywatch for the week of August 15, 2022
Mon Aug 15, 2022 SUN FACTS
It’s at this time of year that I really understand the power of the sun, especially here in Florida when the sun is very high in our sky in the middle of the day. The sun’s diameter is about 865,000 miles. That’s over a hundred times the diameter of the Earth. And in terms of volume, a million Earths could fit inside it. The Sun's mass is 333,434 times the mass of our planet. The sun contains 99.86% of the mass of the entire solar system! Its surface temperature is over 10 thousand degrees Fahrenheit, while its core temperature is 27 million degrees! The thermonuclear fusion processes that take place there, as hydrogen is converted into helium, supply us with pretty much all of our light and energy. So even though we’re 93 million miles away from the sun, it’s big enough, and hot enough, to keep things sizzling here in sunny Florida.
Tue Aug 16, 2022 DON’T STARE AT THE SUN!
The sun is so bright that it's difficult to look anywhere near it because of its brilliance. One rumor often heard is that the Italian astronomer Galileo went blind from viewing the sun through a telescope, but it’s not true: he used his telescope only to project the sun’s image onto a viewing surface, which is safe. Long before telescopes, ancient Greeks observed and described large sunspots, perhaps 40,000 miles across that sometimes appeared on its face. They did this by watching the sun only while it was rising or setting, and at its dimmest. As you’ve guessed, this is definitely NOT a safe practice: even though the sun’s visible light is cut down by the thick column of air at the earth's horizon, the sun is still emitting invisible radiation which can blind you. So never stare at the sun, even at the beginning or end of the day.
Wed Aug 17, 2022 SCORPIUS – MAUI’S FISHOOK
Scorpius, with the bright red star Antares marking its heart, can be found above the southern horizon this evening; it 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.
Thu Aug 18, 2022 HELIUM DISCOVERED; SOLAR SAFETY
On August 18, 1868, the astronomer Pierre Janssen viewed the sun during a total solar eclipse and using a spectroscope, which is kind of like a prism, but with much more detail, he saw dark absorption lines in the sun’s spectrum that had never been seen before. Janssen had found a new element. It was named after Helios, the Greek sun god. That’s right, helium was discovered in the sun before it was found on earth, which makes sense, as helium is so light that unless it’s trapped in the earth or contained in a balloon, it leaks out into space! A word of caution: don’t stare at the sun as it can blind you. Only with proper solar filters, or during the brief moments of totality of a solar eclipse is it safe to view the sun; and if you never leave the United States, you won’t see a total eclipse until the year 2024.
Fri Aug 19, 2022 HOW TO SEE A BLACK HOLE
In the summer evening sky, there are three bright stars high overhead which are known as the Summer Triangle. Inside this triangle, in the neck of the constellation Cygnus the Swan, there is a great mystery. It is a black hole called Cygnus X-1. We can't see it directly because its gravity field is so intense that light can't escape it. But we know that it is there, because we've discovered an incredible amount of x-rays pouring out of this part of the sky. Cygnus X-1 is part of a binary star system. Gas from its companion, a massive blue giant, is being pulled from it to feed the accretion disc surrounding the hole; it’s here that the x-rays are being made, just outside the black hole's event horizon - its point of no return, about 2500 parsecs, or a little less than 48 quadrillion miles from Earth.