August 2000 Sky from the Keeble Observatory
It has been said that the universe is not only stranger than we imagine, but that it’s stranger than we ever could imagine. Beyond its population of mundane objects like stars, planets, and galaxies, it’s also the home of some truly amazing beasts called black holes. Once thought to be a mathematical curiosity, a bizarre consequence of general relativity wholly unlikely to exist in reality, we now have strong observational evidence that they are not uncommon. Supernova detonations could produce them with roughly the mass of our Sun. Super massive black holes are found at the core of many galaxies, including our own, where we find a black hole a million times more massive still.
In Einstein’s General Theory of Relativity, we learn that gravity manifests itself by warping space and time in the vicinity of objects with mass. The greater the mass, the greater the distortion. A black hole represents a distortion so great that even light cannot escape. The distortion is actually in the four dimensions of space-time, so it may be useful to represent this curvature in a simple way. Think of a stretchy sheet of rubber held flat like a table top. Place a marble in the middle and it stretches, distorting the flat "space" in its vicinity while leaving distant regions undisturbed. Rolling another marble nearby would cause the two to interact, and they would come together like two people on a mattress rolling to the center of the bed. Yet, if the second marble is moving fast enough, it could easily escape the influence of the first one.
A bowling ball would stretch the sheet even more! A marble trying to roll past would have to move much faster to escape. . If there were a maximum speed for rolling the marble, its rescue would be impossible. Indeed, a big enough bowling ball would stretch it so much that the region around the ball might actually "pinch off" - that’s a black hole. The maximum speed limit for our universe is the speed of light, and even light does not travel fast enough to escape a black hole.
But, the distortion of the black hole is also a distortion in time. General Relativity allows the possibility that the "pinched off" region of space-time may reconnect at another location, producing a so-called wormhole. This would distort space-time so much that two distant points would be connected via a shortcut through the very fabric of space and time. And – here’s where the time travel aspect comes in – there’s nothing in relativity theory which requires that the two ends of the wormhole have to be at the same time! One end could be in our present, the other at some point in the distant past or future. Travel through the wormhole would be tantamount to traveling in time.
Of course, there’s a little problem … relativity theory does tell us that wormholes are not stable phenomena. The extreme distortion of space-time near the horizon of the wormhole should pull it closed in a matter of microseconds. Some pretty fantastic technology would be required to keep it from closing so that it could be used as a corridor for travel.
Lunar phases for August: First Quarter on the 6th at 9:02 pm; Full Moon on the 15th at 1:13 am; Last Quarter on the 22nd at 2:52 pm; New Moon at 6:19 am on the 29th.
This month sees the return of a bright planet to the evening sky, as Venus emerges from behind the Sun. It will set 45 minutes after the Sun to the WNW at the beginning of the month, stretching its appearance to nearly an hour by month’s end. It will drift towards the south as August advances, setting nearly due west by the 31st. Jupiter and Saturn will be high and bright to the ESE just before dawn, with Saturn about 5 to 10 degrees above and to the right of Jupiter. As Earth catches up to Mars in its orbit, the Red Planet will become visible in the early morning low on the ENE horizon, getting easier to see later in the month. The Perseid meteor shower makes its annual return this month, but viewing will be a bit tougher this year. The best view will be around the 12th, in the roughly one hour from moonset to morning twilight. As always, you’ll need to get away from city lights for a good view.
Looking overhead at about 10:00 pm at mid-month, we see the brilliant star Vega almost directly at zenith. In the same constellation (Lyra) we can also pick out the second brightest star (beta Lyrae) fairly easily. Binoculars will reveal this one to be a binary, and a modest telescope will allow you to see that it’s really two binaries, known as the "double double." Absent the bright moon, a clear night may also allow you to pick out the Ring Nebula in the same field of view. A bit to the east finds Deneb at the tail of the Swan in Cygnus. The head is marked by the beautiful double star Albireo, whose two stars are strikingly different in color. You’ll need a small telescope to get a good view. Coming into view over the northeast horizon is the faint constellation Andromeda, best known as the direction towards the Andromeda Galaxy. This system of some 100 billion stars is some 2 million light years distant, and probably looks to us much as our Milky Way Galaxy would look to observers there. It is the most distant object visible to the unaided eye, though it is only one of over 100 billion galaxies in the observable universe.
From Lyra to the west, your binoculars will sweep through Hercules – look here for the great Globular Cluster, a mere 100,000 old stars orbiting our own Galaxy only a few tens of thousands of light years distant. That bright star to the west is Arcturus in the constellation Bootes. Low to the southwest is Antares, the bright red heart of the constellation Scorpio. The broad disk of the Milky Way cuts the sky almost in half, sweeping from southwest past Antares up through Cygnus and on to the northeast.
Copyright 2000 – George F. Spagna, Jr.