Are we alone in the universe? Maybe not!
Are we alone in the universe? Maybe not! This artist's conception provided by the Harvard-Smithsonian Center for Astrophysics depicts an Earth-like planet orbiting an evolved star that has formed a stunning "planetary nebula" (AP photos / NASA)
Are we alone in the universe? Maybe not!
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Earth has a few more near-twin planets outside our solar system. They make for tantalizing possibilities in the search for extraterrestrial life.

Astronomers have announced that depending on definitions, they have confirmed three or four more planets that are about the same size as Earth. The planets are in the not-too-hot, not-too-cold "Goldilocks Zone" for liquid water to form.

These planets are likely to be rocky like Earth, and not gas giants or ice worlds. They get about the same heat from their star as we get from the sun. That's according to the latest results from NASA's planet hunting Kepler telescope.

But don't book your flights yet.

They may be close to Earth in size and likely temperature in the gargantuan scale of the universe. But they aren't quite close enough for comfort.

Consider two of the new planets, the nearest to Earth discovered to date. If they have atmospheres similar to Earth's a big if one would be a toasty 140-some degrees. The other would hover around zero, said study lead author Guillermo Torres, an astronomer at the Harvard-Smithsonian Center for Astrophysics.

Life conceivably could evolve and adapt to those temperatures, he said.

Oh, and they aren't actually within commuting distance of Earth. Those two are 500 and 1,100 light years away. A light year is 5.9 trillion miles.

What's important, said SETI Institute astronomer Douglas Caldwell, a study co-author who presented the findings at the American Astronomical Society meeting in Seattle, is that astronomers are a bit closer to finding twins of Earth. That will help answer the age-old question: Are we alone?

"These planets do exist. We didn't know that before," Torres said in a phone interview from Cambridge, Massachusetts. "What we're really looking for is signs of life eventually. We're not there yet. It will take many years but this is the first step."

Torres' team confirmed earlier discoveries and added new ones. It brought the total known number of planets that are no bigger than twice Earth's size and in the habitable temperature zone to eight or nine. But that's only from a short search of a small part of our galaxy. Torres believes that Earth-like planets are common throughout the cosmos, though he cannot prove it yet.

Torres likes to include one planet that would bump the new findings from three to four, but Caldwell said that planet may or may not be habitable.

Torres and Caldwell highlighted the two new planets that are closest in size to Earth. The closest is called Kepler 438-b. It is only 12 percent larger than Earth. It gets about 40 percent more energy from its star than we do from the sun, so it would probably be warmer, Torres said. It tightly circles a small cooler red star with its year lasting only 35 Earth days. The sun in its sky would be red, not yellow.

It may be hot, but "there are bacteria on Earth that live very comfortably in those temperatures, no problem," Torres said.

The other planet is Kepler 442-b. It is about 34 percent bigger than Earth but gets only two-thirds of the energy from its sun as we do, Torres said.

NASA also announced that its planet-hunter telescope confirmed its 1,000th planet outside the solar system. Most are quite unlike Earth and not in the habitable zone. Added to those discovered by other telescopes, astronomers have now discovered more than 1,800 planets that are outside the solar system.

Critical thinking challenge: Why are scientists so interested in planets that are not-too-hot or not-too-cold for liquid water to form? Which forms of life can live without water?

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  • ChrisN0
    1/13/2015 - 10:44 a.m.

    Wow, there are other planets in other universes that are actually like planet Earth, I wish i could live on a different planet but to bad its dozens of light years away and either the temperatures are high or low I dont have a chance living on a different planet anyway.

  • gracieb-Eic
    1/13/2015 - 10:49 a.m.

    I think that we are alone but you never know. There may be real people living on the other planets. They may be living a normal lifestyle and not know we exist.

  • barbarat302
    1/13/2015 - 10:51 a.m.

    Wow that's cool that there could be other lifeforms out there kind of like us, it would be interesting to see how they live opposed to us, it would be interesting to see if there was a twin planet of earth.

  • bryanh719
    1/13/2015 - 10:57 a.m.

    i think that we are not alone do to the fact that some planet like mars have water. Since scientist are finding life on other planet by water. They should also consider if life on other planet don't need water because so far scientist didn't find any sign of life on different planet and some of those plant have water.

  • Madisonm157
    1/13/2015 - 10:59 a.m.

    If we aren't alone in our universe that means there could be other people/things we could interact with and we could befriend the and stay there when the earth is gone.

  • Ariannar103
    1/13/2015 - 11:01 a.m.

    That is so cool! A new planet seems awesome because I would want to visit it but the temperatures that are in 140 F and then hoovering around 0 F sounds flat out horrible! It would be nice to visit a new planet that could have life on it but I don't think I would want to leave earth to go to another planet. Scientist are so interested in planets that are not-too-hot or not-too-cold for liquid water to form because if humans or animals live on a planet they need to have water to drink and in some foods we need to add water. And we can live longer with no food than we can live with no water.

  • citlallis6503
    1/13/2015 - 11:07 a.m.

    I hope they discover another inhabitable planet soon so we can explore more of the universe around us and possibly live on another warm planet!

  • yonim425
    1/13/2015 - 11:22 a.m.

    Scientists are interested in the planets that have water liquid because one day if Earth vanishes we will have to live in a planet with water. If we don't have water in that new planet some people will die of dehydration.

  • jakes-Eic
    1/13/2015 - 11:27 a.m.

    It's not unlikely that these Goldilocks zone planets have liquid water. Hydrogen and oxygen are common elements in the universe, and the boiling point of water is 212 degrees so it would be possible on kepler 438-b to have liquid water.

  • natalier-Eic
    1/13/2015 - 11:29 a.m.

    I think it is cool that people might be able to go to another planet. But, then again it is kind of weird to think we are not alone. I hope they discover it fast so we can see if people can actually go and live on a different planet besides Earth.

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