Archive for August 18th, 2009

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In the footsteps of Galileo redux

August 18, 2009

Galileo_moon_phases

Hoo boy. So all of three days ago I started this blog with a post entitled, “In the footsteps of  Galileo”, about Galileo’s  achievements, IYA 2009, and starting out in astronomy (image above from Wikipedia).

All of three minutes ago I discovered that the Astronomical League has an IYA 2009 project called, “In the footsteps of Galileo”, with instructions for replicating Galileo’s discoveries for those starting out in astronomy. It’s a cool project, and all it takes is a pair of binoculars and some patience (or fortitude; the Pleiades [#4 on the list] rise about midnight right now and aren’t what you’d call “well placed” until 2 or 3 AM).

The duplicated title is a coincidence–Google lists almost 3000 hits for the exact phrase “in the footsteps of Galileo”–but a fortunate one, because the “Footsteps of Galileo” project hits some of the best stuff I was planning on covering on this blog anyway. In particular, I’ve got some posts lined up on how to take the binoculars you probably already have and make the most of them for stargazing. Stay tuned for more–or, if you’re chomping at the bit, download the “Footsteps of Galileo” observing guide, dig the binoculars out of the closet, and get going (don’t forget Stellarium if you need a little help finding things).

If you’re  looking for something just a little more challenging, the Astronomical League’s Galileo Club includes 12 projects for small telescopes or serious binoculars. You probably will need something with higher magnification (15x-20x) than your average birding binos for those, but even a very small telescope should be adequate. Like, er, this one (shown below), which people have been having a lot of fun with despite, or perhaps because of, its $20 price tag.

Galileoscope-with-Box

Both AL projects are also listed on the right under Observing Lists. “In the Footsteps of Galileo” appears as “5 binocular targets for beginning stargazers”, and the Galileo Club appears as “12 objects for binoculars and small telescopes”.

Have fun!

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Mission 2: Eye of the Scorpion

August 18, 2009

Mission Objectives: Bright star, Constellation

Equipment: Naked eye

Required Time: 1 minute

Instructions: Go outside after dark and look south. Look for a distinctly reddish or orangey star above the southern horizon. To the right of it you will see three bright stars making a short vertical arc.

Antares in Stellarium, as it appears right after sunset in the southern part of the US.

Antares in Stellarium, as it appears right after sunset in the southern part of the US.

The red star is Antares, a red supergiant star about 600 light years away. It is an immense star, with a diameter about 800 times larger than that of the sun. If you placed Antares at the center of our solar system, it would swallow Mercury, Venus, Earth, and Mars.

Antares comparison

Antares compared to another large star, Arcturus, and the sun. R stands for 'radius'. Image from Wikipedia.

Antares is near the end of its life. Smaller stars, like our sun, eventually turn into red giants and blow off most of their mass to form planetary nebulae (so named because the near-spherical balls of gas look  like planets in telescopes, not because they actually have anything to with planets), each with a white dwarf at the core. No such “out with a whimper” fadeout for Antares–one of these days it will suffer a core collapse and blow itself apart as a Type II supernova. When this happens, the explosion will briefly outshine the entire Milky Way galaxy. Fortunately, “one of these days” could be thousands or even millions of years from now, so there’s no cause for panic.

We’re actually catching Antares pretty late in the season. The best time to see it is in late May and early June, when it is exactly opposite the sun in the sky. That means it rises at sunset, sets at dawn, and is highest in the sky in the middle of the night. I don’t know about you, but I’m not up very often at those wee hours. By August, Antares is high in the sky at sunset, or as high as it’s going to get.

Here’s the rub: Antares is pretty far south, so observers in the US and Europe need a clear southern horizon to see it. And the farther north you are, the worse your chances get. Here’s what Antares looks like just after sunset in southern England (higher and to the east you can see Altair, which I’m sure you remember from Mission 1).

Antares just after sunset from southern England.

Antares just after sunset from southern England.

Antares is also known as Alpha Scorpii, because it is the brightest star in the constellation Scorpio. The three bright stars to the right of Antares are supposed to be the scorpion’s claws, and the J-shaped hook of stars trailing off to the south and east form its body and tail, complete with a stinger on the end. To see the body and tail I have to take a short walk. From my tree-shrouded driveway all I can see are the claws and the giant red eye, as terrifying in life as it is in mythology.

The constellation Scorpio as it appears from the southern US.

The constellation Scorpio as it appears from the southern US.