Thursday, January 8, 2009

Spock's Star

What exciting times we live in, cosmologically speaking. Last year, astronomers using the Spitzer Space Telescope’s infrared cameras discovered evidence of three giant Jupiter-like planets and two asteroid belts (in other words, a solar system) orbiting the star Epsilon Eridani (EPP-sill-ahn ee-RIDD-uh-nigh). At a distance of only 10.5 light years, this is the closest known solar system to ours.

Fans of Star Trek trivia may recall that Mr. Spock’s fictional home planet, Vulcan, was said to orbit either the star Epsilon Eridani or the star 40 Eridani. Both candidates for Spock’s Star are visible to the naked eye. Let’s see if we can spot them.

1) About two hours after sunset, face south. If you don’t know the cardinal directions at your location and you don’t have a compass, make note of where the sun sets on the horizon. That spot is approximately west. Stand with your right shoulder to the west, and you’ll be facing approximately south.

2) You'll need a fairly dark location, away from bright lights. The bright Moon may interfere with your search since we’re approaching Full Moon on Saturday the 10th. If so, you may want to try again in the middle of next week when the Moon is rising later each night.

Star maps created with Your Sky

3) First locate the distinctive hourglass shape of the constellation Orion the Hunter, rising in the southeast. Draw an imaginary line between the two bright stars at the bottom of the hourglass, Saiph and Rigel. Then extend that line twice its length past Rigel. Make a right angle turn from that line and go south a short ways to the next fairly bright star. This is Zaurak (ZAW-rahk), Arabic for boat. Quite apropos, since we are now in the constellation Eridanus the River (ee-RIDD-uh-nuss). Zaurak is a little bit dimmer than Saiph.

4) Now look towards the two o’clock position from Zaurak, and you’ll see a pair of stars, side by side. The left star is Delta Eridani, and the slightly dimmer right star is none other than Epsilon Eridani, our first candidate for Spock’s Star and the site of the newly discovered solar system.

5) To find 40 Eridani, look towards the eleven o’clock position from Zaurak but a little farther in distance than Epsilon. You should come to a diagonal pair of stars that are close together, about half as far apart as the other pair, Delta and Epsilon. The star on the right is Beid (BEED), Arabic for eggs. The star on the left is 40 Eridani, our second candidate for Spock's Star. 40 Eridani’s traditional name is Keid (KEED), Arabic for eggshells. Beid and Keid are both dimmer than Epsilon.

We can only hope that, if a rocky Earth-like planet is discovered orbiting either Epsilon Eridani or 40 Eridani, astronomers will have enough good humor to officially name it “Vulcan.”

Astronomy Essential: The Sun is a star.

Maybe you already knew this. Maybe not. Or maybe you heard it once a long time ago, and then forgot all about it. Our experience of the Sun— how it fills our days with heat and light and makes our lives possible— is so different from our experience of the distant twinkle lights in the night sky. Perhaps then we may be forgiven if we sometimes forget that our Sun is just another star.

In its physical nature, it’s no different from the stars you see at night. It’s simply a whole lot closer. If we lived light years away on another planet orbiting a different star in the Milky Way, when we looked back at our Sun, we would see that it’s one star among many.

Our Sun is considered a yellow dwarf, because it shines with a yellow light and it’s smallish on the cosmic scale of star size. Although critically important to us Earthlings, and although we couldn’t do without it, the Sun is, well, average.