De Chéseaux's List of 21 "Nebulae" is an interesting bit of history and it leads right into this subject. I imagine he would have loved to have had a pair of fine binoculars. What did those old boys use for their observations? Was it mainly the eye because it was darker back in the 1700s? Have you ever seen instruments that might have been used by De Cheseaux and his colleagues?
If you explain to the folks a little about nebulae, they might become fired up. Hope so. I was grown before I realized there were things to see other than the moon and stars, only because a friend was having occasional star parties. And here is a group spending a good bit of time in some of the best places to see these things.
John D
You may be more of an astronomy historian than I. I did find out that De Chéseaux used both a refracting and reflecting telescope (Gregorian design) in his work. Isaac Newton is credited with first using a mirror for a telescope instead of lenses, and De Chéseaux was observing about thirty years after that. The mirror of the reflector was probably made of speculum (copper and tin alloy that takes a good polish). Yeah, our binoculars have better optics than either of his telescopes.
Ok John D, because you asked, the one-minute nebula class is called to order.
It used to be that anything that looked fuzzy was called a nebula (Latin for "cloud"). As optics got better, it turned out that some nebulae were actually clusters of stars inside or surrounding our Milky Way Galaxy, some really were clouds of gas and dust in the Milky Way, some were shells of gas shed from dying stars, and some turned out to be other galaxies outside our Milky Way. It wasn't until the 1920s that those galaxies were shown to be outside the Milky Way Galaxy!!! Google "Shapley-Curtis Debate" for an interesting read.
Large emission nebulae in the spiral arms of the Milky Way occur in places where there is enough gas to contract by gravity to form stars (the density is rarer than any vacuum on earth, but is "thick" for space). They are stellar nurseries. The more massive baby stars are very hot and bright and ionize the nearby gas, which then glows as the freed electrons find new atoms to recombine with. Eventually, the pressure from the stars' light (yes, even light can exert radiation pressure) blows away the remaining nearby gas and you are left with an open cluster of stars that formed from the gas. Oh there is so much more interesting stuff, but my minute is up, and this is primarily a camping forum.
At midnight during the Pork Rally, Orion will be rising in the east, and Wanderers can train their binoculars to the middle "star" in Orion's sword to see the Orion nebula (M42). It is being ionized/illuminated by four young stars called the Trapezium. In Taurus there is the naked-eye open cluster (where most of the gas is now gone) - the Pleiades (M45). It will also be in the east, rising at about 8 p.m. I'm willing to bet that most Wanderers are already familiar with the Pleiades, and I'm curious as to how many have looked at it with binoculars. It's a great binocular target.
Now, I'll bet John D and others have their own particular favorite objects to share. I've blathered on enough.
