Wander the West: Astro Thread - Wander the West

MarkBC's thread on Jupiter got me to thinking that it might be nice to have a thread on celestial phenomena for Wanderers to check before they head out to their next backcountry camp.



I'll start things off with a faint comet that should be naked-eye from a dark site with no moon in early October, or at least easily visible in binoculars.

Comet Hartley 2

Oh, I thought this was going to be about the vans.


Stars are good!

Thanks for the heads up on the comet.

Thanks for the comet will be looking for it. can anyone see Uranus without binoculars
Kevin.

Sounds good -- useful -- to me.
(the astro-nomical, not the Astro-vehicle )

so what amazing things might we see during the pork rally ?

HERR42, on 25 September 2010 - 01:06 PM, said:

Well, after eating a lot of Good Stuff and drinking all those fine brews, some of you might be flat on your backs, looking up

If you can still hold binoculars steady, you could still look for comet Hartley 2. It will be in the constellation Perseus. A detailed chart is here:

http://media.skyandt...Hartley2-bw.jpg

Jupiter will still be bright. Uranus is just 2 degrees to the north of Jupiter. It will look like a vaguely greenish star in binoculars.

On October 22 the Orionid meteor shower peaks. At peak, there are typically 25 meteors per hour. On the 16th, you may only see a few an hour, on top of the usual "sporadic" meteors, so probably not a "Gee Whiz" event. Viewing is best after midnight, when your spot on earth has turned into the stream of meteoroids, and the moon has set. The big question is, who will still be conscious then?

That's all I have. Maybe other Wanderers will be able to add more. You would think the Pork Rally would be accompanied by great portents in the sky. Let me know if you see any.

A small telescope should be part of the camping equipment. We carry an old Celestron 65 spotting scope. According to a quick search of the Web, newer versions of the same telescope can be had for about 70 bucks. This telescope uses a Cassegrain mirror in the front of the scope which makes it very small, easy to use, and powerful. Unfortunately, our scope does not adapt to a camera well, which is a disadvantage. However, with this little telescope, we have seen the rings of Saturn when camping at a remote place in Arizona. That is a pretty good test.

In addition, a spotting scope like this, with an erect image, has great value for looking at objects on the surface during the day, including but not limited to wildlife. A telescope can add greatly to the enjoyment of the outdoors and oft times, a little scope can see more than a big one.

The astronomer who posted earlier is being a little disingenuous when he says he only brings his binoculars. At most star parties a good pair of binoculars is mounted on a tripod for viewing, in addition to the telescopes, because they work better than telescopes for some things. Thus, a pair of binoculars is a good place to start. Most already have them. So, start with your binoculars and learn to use them. Mount them on a tripod. Most folks already have these two items and only need to start using them. John D

Disingenuous? Oh, well, maybe.

JohnD is right about binoculars, though. Here are a few more practical notes about them.

You all know that binoculars are designated by magnification x objective aperture (in mm) - e.g. "7x35". If you divide the aperture by the magnification, you get the exit pupil in mm. For astro binoculars you usually want to match the exit pupil to the diameter of your dark-adapted (dilated) pupil. For young people, that is typically 7 mm. It usually gets smaller as your eyes age. Also, the larger the objective lenses, the more light is gathered, so astronomy binoculars tend to be large.

So, 7x35 binocs have an exit pupil of 5 mm. A pair of 7x50 binocs gives you an exit pupil of 7 (close enough). The 7X50 would allow you to get a little more light into your eye and see fainter objects with their larger objective aperture, and it would all go into your dark-adapted pupil. 7x35 binoculars are okay for astronomy use, 7X50's are better. Even so, if you already have 7x35's, there is a lot to see at night with them, so no need to go spend big bucks on astronomy binoculars unless you get hooked on the hobby.

Also, the larger and heavier astronomy binoculars pretty much require a tripod or mount, since they are very hard to hold steady for any length of time.

highz,

Thanks for the additional information on binoculars, details I had long forgotten. I appreciate the very practical refresher. Hopefully, this will inspire the folks to dig their binoculars out and start using them. There is so much to see. I have a pair of Nikon 7x50s that I don't take in the camper because they are rather heavy. Next trip out west, they are going with us, thanks to your information.

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

John D, on 25 September 2010 - 10:48 PM, said:

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.