Jason Shilling Kendall: Citizen Astronomer

William Paterson University
Amateur Astronomers Association of New York

833 more new planets?

2013, November 5

One of the most important scientific discoveries is happening as you grow up. The Kepler Space Telescope (KST), which recently lost its steadying gyroscopes, has found 3538 planetary candidates. These planets don't orbit our Sun; they orbit their own star. That's why we call the Exoplanets. "Exo" is a great prefix meaning "outside". So these are planets outside of our Solar System. They are all so far away that we will never get there with any spaceship known to humanity. However, we are trying to answer a big question with these exoplanets: Is the Earth normal; are there more "Earths" out there? Before Kepler was launched into space, no one had any idea if there were Earth-like planets out there.

Now we know.

First, how it worked. Since it's up in space trailing the Earth in its orbit, it never had 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. Now, there's no one on board this spaceship. It's just a telescope with some gyroscopes and some tiny guidance jets. So astronomers don't "open the dome" or look through an eyepiece like a telescope you might use at a star party (like the upcoming Urban Star Fest in New York City on November 9 and 10. www.aaa.org)

So, it's up there in space, and 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 the Sun has planets around it, it seems right that at least some stars might have planets around them, too. But the stars are so far away, and the planets are so tiny, and don't emit light, how do we see them? It's like looking for a firefly in front of a lighthouse searchlight. But, we don't care about the firefly's little light, we care if the firefly flies in FRONT of the light as we are looking at the searchlight. The lens of a searchlight is big, and a firefly is small. 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. But that's just what the Kepler Space Telescope did.

Let's imagine that you take a rocket ship all the way to the star Betelgeuse in Orion. That's about 600 lightyears away. If you looked back at the Sun, and everything just HAPPENED to be lined up perfectly, then the Earth would dim the Sun's light by about 1 part in a million. It was shown that the Kepler Space Telescope could do that when it was first launched. So, now we stare and wait for it. KST stared at a patch of sky in Cygnus that contained millions of stars. Of those millions or stars, about 150,000 were similar to our Sun. If planets around stars are around every star, then the chance that the stars had planets that would pass in front of them from our point of view is about 1 in a hundred.

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 it means that the scientist knew that if planets were common, then they would see at least a thousand exoplanets.

On November 4, they announced a grand total of 3538 potential exoplanets. Of those, 674 are about the same size as the Earth. Of those, about 5 are perfectly placed from their star, not too far, like Pluto and not too near, like Mercury. They 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.

If those are the ones we've seen, then planets are MORE common than we ever expected. It means that there are about a hundred billion stars in our Milky Way, and trillions of planets, with many of them in their Goldilocks zones: where water could exist on their surfaces.

This was an open question in 2008, but now, in 2013, we know that the universe loves to make planets.

The vast majority of the 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.

Five planets have been found in the so-called Habitable Zones of their stars, which means that the expected temperature at their distance from the star is just right for liquid water to be on the surface. The most important habitable-zone planet is Kepler 22b, the first one found. 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.

But, now we at least know that somewhere out there, yet to be discovered, is at least one other planet much like the Earth, sitting next to a star similar to the Sun. And we'll learn more about these planets as you grow up. You'll learn what they are like as the world's largest telescopes stare at them with different cameras that might be about to detect the air in the planets. atmospheres.

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.

Published on Here There Everywhere, Kids News


William Paterson University Department of Physics American Astronomical Society Amateur Astronomers Association of New York Astronomical Society of the Pacific