by Kim Malville
October 3: Look to the southwest about 45 minutes after sunset. The waxing crescent moon is within a degree and a half of Jupiter. Off to the southwest in a line with Jupiter and the moon is the red giant, Antares, the heart of the Scorpion.
October 4: Off to the left of Jupiter is Saturn. This night there is a long arc connecting Saturn, Jupiter, the moon and Antares, covering some 30° of the sky.
October 5: Again some 45 minutes after sunset look to the south-southwest where you will find the first quarter moon, which has moved eastward and is close to Saturn, above the handle of the Teapot of Sagittarius.
October 13: Full moon.
October 17: The waning moon rises in Taurus some 21⁄2 hours after sunset. Look east to see the moon below the Pleiades and close to red Aldebaran.
Oct 21-22: The Orionid meteor shower peaks in the evening of the twenty-first. The meteors radiate out of the hunter Orion’s raised club in his right arm, near the star Betelgeuse. The tiny particles that briefly blaze in our sky are pieces of Halley’s Comet that were carried out by evaporating gas and dropped along its orbit. It is now near its furthest distance from the sun, some 3 billion miles from Earth, but its fragments fill its elliptical orbit. It will not return to our vicinity in 2061, but, just think, you can catch a glimpse of a piece of the most famous of all comets on this night! Usually, meteor observing is best between midnight and dawn, but in this case it would be best to get outside between midand late-evening. There should be perhaps 20 Orionids per hour. You can identify them by following their trail back. It that track intersects with Orion, it’s an Orionid.
Oct 29: Just after sunset look to the southwest to see the two-dayold tiny crescent moon. Nearby will be Venus, as an evening-star, which will set an hour after the sun.
Constellation of the Month: Cygnus the Swan
Directly overhead at 9pm you will find the bright star Deneb in the constellation of Cygnus, the Swan. Cygnus is flying to the southwest, along the Milky Way. Deneb, lying in the tail of the swan, is a member of the Summer Triangle, which also contains Vega in the constellation of Lyra and Altair in Aquila the Eagle.
Cygnus contains on its long neck the first discovered black hole known as Cygnus X-1. It was located using X-ray detectors aboard a rocket launched from White Sands Missile Range in New Mexico way back in 1964 when black holes were still mythical beasts. Because X-ray emissions from space are blocked by the Earth’s atmosphere, observation of celestial X-ray sources is not possible without lifting instruments to altitudes where the X-rays can penetrate. After many
The black hole Cygnus X-1 in the neck of the Swan.
decades of investigation, now we know that the black hole is no long mythical and has a mass of 15 times the mass of the sun. Its size is truly tiny for a star, only about 25 miles. Such a large mass, contained in such a small volume, means that its gravitational field is strong enough to prevent the escape of anything, including light.
One fascinating feature of this black hole is that it is part of a double star system. Its companion is a huge blue supergiant, some 20 times larger than the sun. It is gravitationally distorted, with a tear-drop shape, losing matter to the black hole. Clumps of matter spiral away, and just before they are swallowed by the black hole, they give off the bursts of X-rays that are detected on earth some 6000 light years away. We are blessed to live at a safe distance from this monster.
Cygnus X-1 was the subject of a notorious bet between Stephen Hawking and Caltech physicist Kip Thorne. Hawking bet against the existence of black holes in the region. Hawking later described this as an “insurance policy” of sorts. In his book A Brief History of Time he wrote: “This was a form of insurance policy for me. I have done a lot of work on black holes, and it would all be wasted if it turned out that black holes do not exist. But in that case, I would have the consolation of winning my bet, which would win me four years of the magazine Private Eye. If black holes do exist, Kip will get one year of Penthouse.” Hawking lost the battle but won the war. Black holes do exist!