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CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.
If you're like me, you have probably seen Jupiter, Saturn, the Orion Nebula, and all of the sky's showpiece objects more times than you can count. And while they are truly spectacular and well worth revisiting, you may be looking for something new, something challenging to observe.
Just spotting the gigantic Pinwheel Galaxy, M101, can sometimes be challenging enough. Its low surface brightness can drive suburban observers crazy, especially when we see photographs that show it so big and bright, or that it is listed as 8th magnitude. It all comes down to surface brightness, or more accurately, lack of surface brightness. Seeing the dim glow of the galaxy's small core, or the even dimmer glimmer of the surrounding spiral arms, can take a concerted effort. But with time and patience, M101 is visible, with difficulty, through 50-mm binoculars even given a suburban sky with a naked-eye limiting magnitude of perhaps 4.5.
Vesta turns out to be more like a mini-planet than like the chunks of rock most think of as asteroids. Dawn's measurements of the gravity field provided good evidence that Vesta's interior is separated into layers, much like Earth did as the planet was forming. Vesta's dense core - apparently once molten, but now solidified - is composed principally of iron and nickel, just like Earth's. Estimates place it at 125 to 150 miles (200 to 250 kilometers) across. Surrounding that is the mantle, which in turn is covered by the veneer of the crust, about 12 miles (20 kilometers) thick. It is now believed that early on Vesta was likely still accumulating material to become a full-fledged planet when Jupiter's immense gravity intervened, putting a stop to that. As a result, when we look at Vesta, many believe that we are seeing a protoplanet frozen in time.
Messier did not live to see a second edition of his catalog, but objects 104 through 110 have been added posthumously by others. M109 joined the ranks in 1953, when astronomy historian Owen Gingerich noted Messier's observations of six additional "Méchain objects," now known as M104 through M109.
Last April, this column profile the dwarf spheroidal galaxy Leo I, discovered by chance in 1950 by astronomers Robert Harrington (still no relation!) and A.G. Wilson as they were scanning the Palomar Sky Survey. I ended that column saying that "Using the right eyepiece and knowing the field will help you add this dwarf spheroidal to your list of conquered challenges with comparative ease. But don't get too cocky. Spotting its sibling, Leo II is an even greater challenge. But we will leave that for a future column." Well, that future is now.
You've heard of the Andromeda Galaxy and the Orion Nebula, but how about the Orion Galaxy? Probably not. But would you believe the New General Catalog lists 21 galaxies in Orion, and the Index Catalog adds another 9? That's a pretty respectable tally. Of those 30 Orion galaxies, I find this month's challenge particularly intriguing because it lies so close to everyone's favorite winter deep-sky object, M42. Yet, I am sure that very few observers have seen it.
The Moon's terminator is a fascinating sight through all telescopes. Here, along the lunar sunset/sunrise line, lighting can strike familiar lunar features in very unusual ways, transforming them in ways that go unsuspected when the Sun rides high overhead.
Not long after I got my first "good" telescope, my 8-inch Criterion RV-8 Dynascope Newtonian reflector, as my Christmas gift in 1971, I became fascinated with the Perseus Galaxy Cluster. One reason I am so fond of this collection of more than 500 galaxies is that the cluster grows as the telescope's aperture increases. Small backyard scopes will show the two big kids on the block, NGC 1272 and NGC 1275, but even the largest amateur instruments fail to show all of the "little guys."
Did you know that I discovered a comet in the fall of 1973? I was out with my venerable 8-inch Criterion RV-8 Dynascope Newtonian reflector, just hopping around the autumn sky, when I noticed stars weren't focusing sharply. Thinking the telescope's collimation was off, I aimed at a nearby bright star to check whether the silhouette of the secondary mirror was centered correctly in the star's out-of-focus image. After I tweaked things a bit, all appeared well, so I focused on that star to check things before moving on. Lo and behold, I saw a dim blur of light right next to the star! Checking things further, it wasn't an internal reflection or an optical aberration.
The canvas on which our picture of the universe is painted relies on the unwavering acceptance of Hubble's Law. Hubble's Law states that a relationship exists between the distance to a galaxy and the speed at which it is receding from us. The farther away a galaxy is, the greater the speed of its recession and farther its spectral lines are shifted toward the red end of the spectrum. For Hubble's Law and the Red Shift Principal to be valid, it must work for not just a few galaxies, but for all. And indeed, it does -- well almost.