Archive for December, 2009

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Mission 14: Three Astronomical Treats for Naked Eyes, Binoculars, and Telescopes

December 21, 2009

Mission Objectives: Bright Stars, Constellation, Open Cluster, Nebula

Equipment: Free star map, Naked eye, Binoculars, Telescope

Required Time: 10 minutes

Related Missions: Cassiopeia and the Double Cluster

Introduction: I’m in Oklahoma for the holidays. My best observation here so far didn’t require any optical aid at all. Remember last month when I was skunked in my quest to view the young crescent moon within 40 hours of new? On Thursday, December 17, the night after I got into town, I saw the 38-hour-old crescent moon in the western twilight over Oklahoma City, thus fulfilling the last requirement I had left for the Astronomical League‘s Lunar Club. I e-mailed in my completed log sheets on Saturday.

Instead of bringing a little scope with me, I borrowed back the one I had loaned to my brother. It’s a Synta MC90, another 90mm Maksutov-Cassegrain, but unlike my other little Mak it’s a short focal length, widefield scope. I got it out last night to show my nieces the waxing crescent moon, Jupiter, and the Pleiades.

Instructions: Speaking of the Pleiades (M45), they’re one of the best astronomical treats for a clear winter evening. Finding them is easy: look to the east after dark, and find a little knot of stars that looks a bit like a cooking pan. This is not the Little Dipper, although you’d be surprised at how many people think so on first spotting it. If you have a hard time finding the Pleiades, look for the 3/M/W of Cassiopeia, head past the Double Cluster to Perseus, and follow the lower of the two sweeping lines of stars that make up that constellation; the cluster is just off the end of the line. The Pleiades are pretty to the naked eye and probably best in binoculars. All but the widest-field scopes will have a hard time putting the whole cluster in the eyepiece, and even if you manage it, it’s prettier if you can see the cluster as a cluster, with a little open space around it. So this is one of those times that–in my opinion–binoculars trump a telescope.

If you have found the Pleiades, drop straight down (east) to find a V-shaped association of stars. These are the Hyades, another open cluster, in the constellation Taurus. One leg of the V is anchored by a big red giant star, Aldebaran, whose color is obvious even to the naked eye. You can pan around the Hyades with a scope if you like, but the cluster is so big that it really demands binoculars; binos fall right into the sweet spot of putting a lot more stars in your eyes without overly narrowing the view or getting you lost.

From the Pleiades, on to the Hyades, and farther on east you come to Orion, the most magnificent constellation in the sky. Find the three bright stars in a line that form his belt, and then three dimmer stars in another line that form the sword hanging from the belt. The middle of the three stars in the sword is not a single star at all. Rather it is M42,  the Great Nebula in Orion, a vast cloud of gas and dust, dozens of light years across, which is illuminated by the bright young stars burning within.

M42 is what I call a total object: like the moon, it looks good no matter what you use to look at it, and the more you look, the better it gets. With the naked eye, the nebula it is a faintly fuzzy star at the heart of a striking and majestic constellation. With binoculars, you’ll see a bit of nebulosity set amidst the rich starfields of Orion’s sword. In a small telescope, the full glory of the nebula starts to unfold, with glowing streamers of gas and dust spread out like an eagle’s wings. The central star will split apart into a group of four, called the Trapezium. Pour on more aperture and magnification and the view just keeps getting better. If the skies are clear and steady you may pick up a couple more stars in the Trapezium, and the surrounding clouds of gas and dust will start to look like clouds, with delicate knots and swirls.

And on it goes. You are not going to exhaust M42, not in a lifetime of observing. People with telescopes that require large trailers for transport, who have seen M42 literally thousands of times in their observing careers, still gaze into the heart of the nebula for minutes and even hours at a time. The bigger the scope, the darker the skies, the longer you look, the more there is to see.

But, hey, don’t think that if you don’t have a monster scope it’s not worth looking. Remember, M42 is a total object; it looks good at any scale. If the thought of setting up a scope in the cold and dark does not appeal, at least pop outside for a five minute session with binoculars. Make it a present to yourself.

Happy holidays!

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The persistence of mystery

December 10, 2009

Wired has a story about the hexagonal storm around Saturn’s north pole.

I love it. Things like this, the methane that comes and goes on Mars, the disequilibrium in Venus’s atmosphere, and transient lunar phenomena, are useful reminders that the other worlds of the solar system are, in fact, worlds. Our plumbing of the mysteries of these worlds, even for so comforting and familiar an object as the moon, is not even really started. There are plenty of physical processes here on Earth that are not well understood, so we should feel pride, but no comfort, that we have sent a handful of probes and gotten a little dust on the boots of our astronauts and the wheels of our rovers. Just think how much we’ll know after a geologist has spent as much time on Mars as Spirit and Opportunity. On one hand, our knowledge then will dwarf our knowledge now; on the other, our exploration of Mars will then be just beginning in earnest.

In Cosmos, Carl Sagan said, “How lucky we are to live in this time, the first moment in human history when we are, in fact, visiting other worlds.” I’m on board with that.

Hat tip to Mike.

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Mission 13: Pegasus to Andromeda

December 7, 2009

Mission Objectives: Constellation, Galaxy

Equipment: Sky map, Naked eye, Binoculars, Telescope

Required Time: 5 minutes

Related Missions: Cassiopeia and the Double Cluster

Instructions: Go outside after dark, look up high in the east, and find a big square of stars surrounding a whole lot of nuthin’. That’s the Great Square of Pegasus. If it doesn’t jump out at you, punch it up in Stellarium, print out  a free sky map, or follow the other middle leg of the Cassiopeia W, the one that doesn’t point to the Double Cluster.

The Great Square of Pegasus isn’t all in Pegasus; the star at the northeast corner actually belongs to the neighboring constellation of Andromeda. But the square is such a handy signpost that most people ignore the official constellation boundaries as set out by the International Astronomical Union.

That northeast corner star is the anchor for two almost identical chains of stars, one of which looks like a fainter copy of the other. Go from the second star in the brighter chain to the second star in the dimmer one, and then on in the same direction for an equal distance, and you’ll come to M31,  the Great Nebula in Andromeda.

M31 was named Back In The Day when the term “nebula” was used for any hazy patch in the sky. These days “nebula” means an interstellar cloud of gas and dust, any one of the many that litter the arms of spiral galaxies. They come in lots of flavors, which I won’t cover here; the important thing is that nebulae are comparatively tiny parts of galaxies.

M31, or the Andromeda Galaxy, is not just a galaxy; for stargazers in the northern hemisphere, it’s THE galaxy. From a dark site you can see it with the naked eye, and in fact at two million light years away, it is the most distant object that can be easily observed without optical aid (I qualified that with “easily” because there are a handful of more distant galaxies that can also be seen with the Mark 1 eyeball; pick up the current issue of Astronomy magazine and check out Stephen O’Meara’s column to learn more).

In binoculars, the Andromeda Galaxy looks like a pretty oval haze with a bright core. As you go from binoculars to small telescope to big telescopes, the amount of visible detail increases but the field of view usually decreases, and it can be hard or impossible to fit the whole thing into the field of view of a long focal-length telescope. Think of that, a galaxy so big and so close you can’t see it all with most scopes! It’s so close that people with monster Dobs regularly amuse themselves by picking out its globular clusters, whereas small-scope folks like me find the globs in our own galaxy to be plenty challenging.

The very, very small version of Rob Gendlers' very, very large M31 mosaic.

If you want to see M31 in all its glory, you must get over to Rob Gendler’s site and check out the stupendously huge mosaics on his galaxies page. One of his images has a resolution of 21,904 x 14,454 pixels and at least as of 2009 was the highest resolution image ever made of a spiral galaxy, period.

You may also know that the Andromeda Galaxy is destined to collide with our own Milky Way in a few billion years, setting off massive bouts of star formation as the two repeatedly pass through each other and eventually merge into something bigger and stranger, probably an elliptical but possibly a super-spiral or even a ring galaxy. Should be a pretty good show for whoever is around to see it.

Don’t wait up though. M31 is high overhead in the early evening and pretty good viewing until the wee hours. Go check it out.

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Friday pretty picture two-fer

December 4, 2009

First up, check out this awesome polar ring galaxy from APOD:

Ring galaxies are weird beasts to begin with, with a giant ring of stars, gas, and dust around a central core instead of the usual spiral arms. Polar ring galaxies are even weirder, in that the ring is offset from the axis of the central disk. Think about what it would be like to live on a planet in such a galaxy: depending on where the planet was located and the season, there might be two “milky ways” of light arching over the night sky.

And speaking of the Milky Way, check out these awesome posters celebrating the view of the night sky from the US National Parks. The posters were created by Dr. Tyler Nordgren, who toured the national parks a couple of years ago to document the night sky and educate people about light pollution. I got to see him speak at an SBVAA meeting last year, and I’m looking forward to his forthcoming astrophotography book, which will chronicle his experiences on his national park tour.

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Hubble Advent Calendar!

December 2, 2009

This giant, beautiful Space Thing is Really Out There.

Once again, the Boston Globe’s Big Picture feature is doing a Hubble advent calendar. Every day between now and Christmas, you’ll get another brain-exploding picture of some unspeakably huge and distant space thing. Point your browsers here.