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Earth 2.0?

November 6th, 2013

Image credt: NASA

by Jason Kendall

833 more new planets?!

One of the most important ongoing scientific discoveries is happening as you grow up, and NASA made a huge announcement about it on Monday.

They announced 833 more possible new planets … bringing scientists using the Kepler Space Telescope … to a grand total of 3,538 possible planets!

Of those, 674 are about the same size as the Earth. Of those 674, about 4 of them are perfectly placed from their star — not too far, like Pluto and not too near, like Mercury (in the so-called “ Goldilocks ” zone).

Soooo, could there be life?   Are there other “Earths” out there?

Scientists said their findings mean that 22% of stars similar to the sun in the Milky Way are orbited by Earth-sized worlds that could possibly hold life. That means that as many as two billion planets in our galaxy may be suitable for life.

So, we still don’t know for sure but this is a big step toward finding out.

These “potential planetary candidates” don’t orbit our Sun; they orbit their own star.  So they’re called exoplanets.  “Exo” is a prefix meaning “outside”.  So these are planets outside of our Solar System (but still inside our Milky Way Galaxy).  But they’re all so far away that we will never get there with any spaceship known to humanity.

So how do we know they even exist?

They were discovered by scientists through the Kepler Space Telescope. Before Kepler was launched into space, no one had any idea if there were Earth-like planets out there.

The Kepler Space Telescope is up in space, not down on Earth. Since it’s up in space trailing the Earth in its orbit, it doesn’t have to worry about clouds or rain or the Moon or daytime.  All it did was look at the same patch of sky for the four years it was operating. There’s no one on board this spaceship,  It’s just a telescope with some gyroscopes and some tiny guidance jets.  It might sound boring to stare at the same patch for four years, but it really isn’t, once you know what’s going on.

Since our Sun has planets around it, it seems logical that at least some other stars might have planets around them, too.

But the stars are so far away, and the planets so tiny by comparison, and they don’t emit light …  so how do we see them?  

It’s like looking for a firefly in front of a lighthouse searchlight.  We don’t actually care about the firefly’s little light, we care if the firefly flies in FRONT of the big searchlight.  If we are looking at the searchlight from far away with a REALLY good light meter, then we just might be able to see the dimming of the searchlight as the firefly flies in front of the light.  The little firefly blocks a tiny amount of light, and the searchlight dims by a REALLY small amount.  That’s just what the Kepler Space Telescope saw when planets would pass in front of their sun.

That means that if you waited long enough for the planets to pass in front of their stars, and never stopped staring at them, then you could catch the planet “in the act”.

And, if those are the ones we’ve seen from looking at just one patch of space, then we can say with some confidence that planets are MORE common than we ever expected.  This was an open question in 2008, but now, in 2013, we know that the universe loves to make planets!

The majority of the newly discovered planets are really big, like Jupiter or Neptune.  But there is a new class of planet, called a Super-Earth, that’s up to twice the diameter of the Earth.  And there are a LOT of these, even more than the Earth-sized planets.

Image courtesy: NASA

So far, the most important “ habitable-zone ” (the ones not too far and not too close to their sun) is planet is Kepler 22b, the first one found. You can read HTE’s story about it here . It’s a Super-Earth, at 2.38 times the Earth’s diameter.  No one will ever get there, since it’s about 600 light years away, which is about 3,642,967,200,000,000 miles.  The distance to the Moon is about 200,000 miles, and the Sun is about 93,000,000 miles away.

Image courtesy: NASA

And we’ll learn more about these planets as you grow up. Who knows, you may even become one of the scientists who help keep making discoveries about it. In the meantime, we’ll keep learning what they are like as the world’s largest telescopes stare at them and learn about their atmospheres as well.

Scientists are still hunting for a planet just like the Earth: same size, same distance from its star that we are from the Sun, and the same kind of star.  But we do know something amazing. It’s no longer science fiction, it’s fact.  And that’s what you get by patiently staring at one little patch of the sky.

For lots of Kepler-based activities, click here .

Jason Kendall is HTE’s awesome space writer. He also teaches astronomy at William Paterson University in New Jersey and does public outreach programs. Speaking of, there will be an Urban Starfest in Central Park on Nov. 9. 


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