Mission 9: The Mote in God’s Eye

November 17, 2009

Mission Objectives: Bright star, Exoplanet

Equipment: Naked eye

Required Time: 1 minute

Related Missions: Hail to the King

Instructions: Go outside after sunset, face south, and find Jupiter. South and east (or down and left) of Jupiter is a bright star called Fomalhaut. Fomalhaut is the only bright star in that part of the sky, so there’s little chance you’ll confuse it with anything else. It’s not a double star, doesn’t have a striking color, and isn’t part of a striking pattern (it’s also pretty far south, at roughly the same elevation as Sagittarius, so if you’re at high latitudes, good luck). Its attractions are entirely cerebral.

Fomalhaut is special because it has an extrasolar planet, Fomalhaut b, which was the first extrasolar planet to be imaged directly by an optical telescope. What’s all that mean? People had been detecting extrasolar planets for years, by measuring the wobble they induced in their parent stars, or measuring the light drop in their parent stars as the exoplanets pass in front of them, and the spectra of exoplanets had even been obtained, but Fomalhaut b was the first to have its picture taken. The Hubble image itself is cool; it looks like the Eye of Sauron.

Now, as of this writing 405 explanets have been found, with more coming almost every month, especially now that the Kepler telescope is up and running. But most of these orbit stars that are very dim as seen from Earth. Fomalhaut rocks because it’s obvious. You can point it out to someone and say, “That star has a planet, and we have taken pictures of it.”

Hubble image at top from NASA, artist’s reconstruction above from the Joint Astronomy Centre. Apologies to Niven and Pournelle for nicking their title.

One comment

  1. I can bag this one! Naked eye, 30 seconds…in spite of light pollution!

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