Phil Plait seemed to appreciate the news just as much. His Discover headline read in all-caps, “ALPHA CENTAURI HAS A PLANET!”

Let’s analyze all of this excitement…

Yesterday, astronomers announced they discovered an Earth-sized planet orbiting Alpha Centauri. The finding is also published in Nature today.

Alpha Centauri lies only 4.3 light-years away—closer than any other star system. And it’s not one star but three—two binary stars similar to the Sun orbiting close to each other, called Alpha Centauri A and B, plus a more distant and faint red companion known as Proxima Centauri. Since the nineteenth century, astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque, lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

A period of 3.2 days means that this new planet orbits extremely close to its parent star, “roasting at perhaps 2,200 degrees Fahrenheit with a surface likely composed of molten lava,” writes Adam Mann in Wired. Not exactly a hospitable neighbor! (Sorry, Mr. Rogers.)

This news comes right on the heels of another exoplanet discovery. On Monday, our friends at Zooniverse announced the first ever confirmed exoplanet discovered by the citizen scientists at Planet Hunters—a gas giant dubbed “PH1” with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune. PH1 resides in a four-star system—twin suns that in turn are orbited by a second distant pair of stars.

These discoveries provide further evidence that, with the number of eyeballs looking for exoplanets (professional astronomers and citizen scientists alike), an Earth-like exoplanet can’t be far off. Again from the Bad Astronomer:

…we’re zeroing in on Terra Nova, folks, and statistically speaking there should be millions of them in the galaxy. It’s only a matter of time before we find the first one.

Image: ESO/L. Calçada

Though it has benefited greatly from the power of online connectivity, citizen science is not a new concept, it’s not all astronomical in nature, and it doesn’t necessarily require a computer.

The oldest citizen science project is the Christmas Bird Count, a census of birds of the Western Hemisphere that was started by the Audubon Society in 1900.  One of the newest is the campaign to monitor the eclipsing binary star system Epsilon Aurigae, where every 27 years one component of the star system blocks the other from view for about 2 years.

In 2007, the Citizen Science Alliance launched an online project called Galaxy Zoo, inviting guests to log in and classify distant galaxies by their shapes—spiral, barred spiral, edge-on, or irregular.  An instant hit, Galaxy Zoo became enormously popular and opened the door for additional projects that included observations of merging galaxies, searches for solar flares and supernovae, and, most recently, classification of features on the Moon, all under the broad project name “Zooniverse”.

Zooniverse follows in the footsteps of one of the best-known online popular science projects, SETI@home, based at the University of California’s Space Sciences Lab and which was launched in 1999.  A more passive approach, SETI@home uses the idle-time on subscribers’ computers to activate a screensaver that doubles as a signal analyzer. The analyzer searches downloaded packages of signal data detected by radio telescopes for patterns that might indicate intelligent activity.

Citizen scientists have much to offer to real science. It was almost a year ago that amateur astronomer Anthony Wesley discovered a new spot on Jupiter that had scientists pointing their telescopes in a new direction. Today, Hubble announced the cause of the spot: an asteroid.