The Kepler Space Telescope, which launched earlier this year to find Earth-like planets elsewhere in our galaxy, showed it's open for business with NASA's announcement that an exoplanet we thought we knew is like nothing we've seen before.
Peering at a large planet orbiting very close to its star, HAT-P-7b, the telescope delivered what one scientist called "exquisite" data, proving that it's ready to start looking for Earth-sized planets in the habitable zones around stars.
Analyzing just 10 days of data, the scientists even turned up a major surprise: HAT-P-7b isn't like Jupiter at all. It has a "dark" side and its atmosphere could be made of relatively exotic chemicals like titanium oxide.
"This planet is not like anything in Earth's solar system," said Sara Seager, an exoplanetary scientist at MIT.
The hottest spot on Hat-P-7b could be more than 1,300 degrees Fahrenheit warmer than the coldest spot. There is no comparable planet around our star.
Kepler's first findings, some of which were published in the journal Science, augur a new level of exoplanetary research, Seager said.
"This exquisite data is just the tip of the iceberg," she said. "We're going to see a new world of exoplanet exploration where discoveries will come much more rapidly than they've come in the last 10 years."
But while we'll be learning more about planets in the universe every month, Kepler's ultimate mission — finding Earth-like planets in the habitable zone — is still going to take years.
The habitable zone is the term astronomers use to denote the distance from a star where orbiting planets wouldn't get fried or frozen. In those locations, liquid water could exist — and that's something that is necessary for life as we know it. In our solar system, Venus, Earth, and Mars lie within the zone. The more planets that Kepler finds in its survey of 100,000 stars, the more likely that Earth-like planets exist in large numbers throughout the universe. And the more Earths out there, the better our chances get of finding life outside our solar system.
The announcement that Kepler is working as designed is great news for the exoplanetary research community, which had been eagerly awaiting the first data from the instrument. 
"It appears Kepler is working at its design precision — the noise level of just 40 parts per million per data point is amazing!" Matthew Muterspaugh, an exoplanet researcher at Tennessee State University, wrote in an email to Wired.com.
Kepler's mission is primarily statistical. It will tell us how many solar systems like ours likely exist in the universe, but the stars in its field of vision are too far away to characterize in much detail. Kepler will be able to tell us that the planet is in the right place, but not whether it's suitable for or home to life.
"[Kepler] will be able to say it's a rocky planet like Venus or Earth, but won't be able to say whether it's more like Venus or Earth," Muterspaugh said.
So, while Kepler will help sort out how likely life is around the universe, it won't actually find any definitive signs of it. The stars that it's looking at are just too far away.
"The downside to the Kepler technique is that the stars tend to be very far away and faint," said Muterspaugh. "This set of stars will not be well optimized for the follow up observations."
The ultimate quest to find other planets that support life will require a series of other missions and telescopes, which focus on planets much closer to home.
First, we'll have to find out which local stars have rocky planets. NASA's first potential mission with that capability is the SIM Lite Astrometric Observatory. It will be able to find Earth-sized planets around 60 stars in our neighborhood.
Once these planets are identified by SIM or other missions like Gaia and CoRoT, NASA will be able to peer at them with the powerful James Webb Space Telescope or a dedicated planet-hunting telescope like the agency's proposed Terrestrial Planet Finder missions.
For planets larger than Earth, the James Webb telescope will be able to characterize them effectively, but for the true Earths, we'll need the more powerful instrumentation of the TPF. It will be a long road from finding the first Earth-like planet with Kepler to knowing how habitable any extrasolar planet is, but if all goes well, scientists think we could have answers by 2020.
"The timeline is set for in 2020 having that image of our brother world out there," Muterspaugh said. "I think that this is a fantastic thing for our generation to do, answering a question that's thousands of years old: are we alone?"
See Also:
- First Light: Kepler Opens Her Eyes
- Planet-Hunting Space Telescope Readies for Launch
- 'She lives! Let's go find planets!': Telescope Launch Successful
- NASA's Planet-Hunting Space Telescope to Launch Friday
- Astronomers Find Hidden Exoplanet in Hubble's Dustbin
- Smallest Exoplanet Is Most Earth-like Yet
- Extreme Exoplanet's Wild Ride
- Astronomers Closer to Exoplanet 'Holy Grail'
- Top 5 Most Extreme Exoplanets
Images: NASA. 1. Kepler is prepared for launch. It was kept covered. 2. An artist's rendering of Kepler on orbit.
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