In our solar system, only one world has just the right size, just the right temperature and just the right home for liquid water. Long ago, at least one other rocky planet had water, too, but it's gone now; Mars dried up and turned to rust. A distant moon called Europa has a lot of water, but too far from the sun's warmth, the moon remains frozen. Closer in, Mercury and Venus are too hot to keep it.
"Between the fire and the ice is this green zone, the habitable zone, where a planet could have liquid water on its surface," said William Borucki, principal investigator on the planet-hunting Kepler Space Telescope. In that zone, conditions are right for thick greenhouse atmospheres, and for planets with sufficient gravity to hold on to them.
Now for the first time, exoplanet hunters think they've spotted not one such world, but three, hanging out smack in the middle of that Goldilocks zone, in solar systems very far from this one. The planets are just a tad bigger than Earth and orbit stars very much like our sun. One system, Kepler-62, has two Earth-sized planets orbiting in the cozy habitable zones. The Kepler-69 system has one possibly habitable planet. These could be the most similar worlds to our own astronomers have ever found.
"They are the best candidates so far for habitable planets outside our solar system," Borucki said.
Here's the breakdown: The Kepler-62 system has five planets in all: 62b; 62c; 62d; 62e and 62f. The Kepler-69 system has two planets, 69b and 69c. Kepler-62e, 62f and 69c are super-Earth-size planets. 62-e is 60 percent larger than the Earth while Kepler-62f is about 40 percent larger, making both of them "super-Earths." They are close together, so much that each would appear like our full moon in the other's sky. Life forms living on either world would not have very far to travel to meet their neighbors.
"Kepler-62e probably has a very cloudy sky and is warm and humid all the way to the polar regions. Kepler-62f would be cooler, but still potentially life-friendly," Harvard astronomer and co-author Dimitar Sasselov said in a statement.
As for the composition of Kepler-69c, scientists are not sure, but its orbit of 242 days resembles that of Venus. They are too small for their masses to be directly measured, but astronomers think they are likely composed of rock and water without a significant amount of gas surrounding them.
Just so it's clear, there are a lot of assumptions in these statements. Astronomers can't know for sure whether the planets in the Kepler-62 system are rocky, or have atmospheres that could provide sufficient pressure to keep water on their surfaces. They make educated guesses about this based on the planets' size--too small to be gas giants, so probably rock worlds like Earth--and their location. This gives an assumption about the amount of radiation they receive from their sun, which could warm the worlds enough to keep water liquid and to impact the weather.
"We are not clear what makes up these planets, because we don't have any [like them] in our solar system. We have to go to models and theory to understand what's going on," explained Thomas Barclay, a Kepler scientist at the Bay Area Environmental Research Institute in Sonoma, Calif.
Based on their size and locations, they could have water. If they have water, they could theoretically, maybe, be host to life. We'll probably never know, because no mission--neither existing nor planned--can detect that. But that doesn't stop planet-hunters from getting excited, and wondering what waterborne creatures may live there. If there are life forms on any of those worlds, they would impact the planets' atmospheres in ways that could maybe be detectable far in the future.
Now into its fourth year staring at 170,000 distant suns, the Kepler Space Telescope has racked up plenty of impressive finds, from adorably tiny scorched worlds to gigantic super-Jupiters to binary star systems harboring planets straight out of Star Wars. Today's news ups the ante, astronomers said.
"Kepler has brought a resurgence of astronomical discoveries, and we are making excellent progress toward determining if planets like ours are the exception," Borucki said, "or the rule."
The papers are published in Science and The Astrophysical Journal.
There's more water on Jupiter's moon Europa than there is on Earth
"...Remember that image from a few weeks back that showed Earth with all its water gathered up in a sphere beside it? Well here's that image again, only this time, it also features Jupiter's moon Europa, along with all of its water. Notice anything interesting?
Based on data acquired by NASA's Galileo satellite, astronomers think the global oceans sloshing around beneath Europa's icy exterior are likely 2—3 times more voluminous than the oceans here on Earth. Not 2—3 times more proportionally, 2—3 times more in total volume.
Yeah. That "little" moon is packing quite the supply of H2O — and with it, scientists think, a significant chance of harboring life...."
A Living Ocean on a Jovian Moon?
But another world in our Solar System doesn’t have to look to the past for its maritime days. Jupiter’s moon Europa not only had water, it has it—likely a vast, globe-girdling ocean, 60 mi. (96 km) deep, just beneath a comparatively thin, 2-mi. (3.2 km) rind of ice. Gravitationally plucked by the tidal tugging of its sister moon Io and Jupiter itself, Europa retains a hot interior, which keeps the water comparatively warm and even pulsing. If that doesn’t sound like a place that could cook up life, nothing does. The only ingredients missing to make Europa’s ocean a potential home to living things have been salt and organic compounds. Now, according to a study about to be published in The Astronomical Journal, they’re not missing anymore. A dip in the waters of Europa, the paper concludes, could be very much like a dip in our oceans, perhaps with all the biology that implies...."
I think this is interesting. If these planets are the same age I wonder if there are human-like beings that are living there at a similar technology level to ours.
When you think about it, after 4.5 billion years what is the only species to have evolved to the point it can create and utilize tools effectively? Humans, why would it be different on a planet almost the same as Earth? There's a reason we evolved the way we did and no other animal has done yet. Why should it be different on a planet so similar to our own?
The same goes for Europa except you lower the amount of sunlight that reaches the moon and add a layer of ice. I'm sure there are bacteria and other life forms there but nothing sentient.
Another article on these planets says the system is 2.5 billion years older than ours.
"Kepler Search Finds Two New Cozy, Possibly Watery Planets Around Faraway Star" they found it in 2013. That's not that exiting, Galalio found a watery planet size moon back in 1610 called Europa, yea it is ice covered but it is one of the most life bearing worlds in our solar system outside earth. We can explore Europa some day in the next 50 years. With the most advanced tech today it will take us hundreds if not thousands of years and trillions of dollars to even reach one of these other worlds...
The planet discoveries are interesting news, they should be target for seti projects. It is a pity it was not mentioned how far away they are.
No doubt in a few decades we will have better equipment and we will find many more planets and we will be able to gain more information about them.
Why Europa over Ganymede? Ganymede is actually planet sized (it's larger than Mercury while Europa is smaller than our Moon). It's warmer than Europa. It has a higher surface gravity than Europa. It has it's own magnetic field as opposed to Europa. It receives ~1/70 of the radiation from Jupiter as Europa does. Evidence shows it has an atmosphere and liquid ocean under an icy surface like Europa, and it's the primary target for study of an ESA mission launching in about a decade.
Europa could have synchronised swimming naked mermaids and it still wouldn't detract an iota from the awesomeness of this discovery of the first Earth-sized planets found in the goldilocks zone.
That's pretty cool. Exoplanets are really amazing and the fact that there is a greater possibility, recently analyzed by Kepler, that there are a lot more Earth like planets out there is great news to hear. I still love the planets of Gliese 581.
lol, I cant help laughing at those clowns who thought planets were rare, and earth was unique in its size and positioning in the entire universe.
Instead of being illegal, drugs should be mandatory for some people who obviously don't function well when sober.
Why would anybody in their right mind doubt that life exists outside Earth? Or say that there is nothing to gain from a human presence on the moon, Mars, Europa etc?
If we don't take these baby steps the only way we will get to the starts is with Extra Terrestrial assistance.