Category Archives: Kepler mission

exoplanets, Kepler mission

Kepler in Search of Distant Earths

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A Near-Earth-size Planet Isn’t Necessarily JUST Like Earth

A artist's concept of Kepler-452b, a near-Earth-sized planet discovered by the Kepler space telescope. Courtesy NASA/Kepler
A artist’s concept of Kepler-452b, a near-Earth-sized planet discovered by the Kepler space telescope. Courtesy NASA/Kepler

The news last week that the Kepler telescope had found a close “cousin” of Earth circling a sun-like star really brought out the speculation among people who don’t actually study planets for a living. The press, of course, ran with the story, calling it “Earth 2.0” and “Earth-like”, neither of which is quite true. However, despite the tendency of supermarket rags as well as serious press to jump on stories like this and carry them to illogical extremes, the discovery of this planet IS a milestone in exoplanet research.

Kepler-452b IS likely to be a rocky world similar to Earth, although astronomers haven’t confirmed that yet. It’s in the habitable zone of its star, so that means liquid water could exist on its surface. Whether it has water, or even an atmosphere, is all still to be determined. This planet is near-Earth-size, meaning it’s close to our planet’s size. Actually, it’s 60 percent larger than Earth, and its 385-day year is slightly longer than our 365-day year. It’s about a billion and a half years older than Earth, which has interesting implications for the evolution of life. Life began on Earth some 3.8 billion years ago, and this new planet has had a LOT longer than that to cook up some life.

Still, that’s not enough to make it Earth 2.0.

Yet.

For that to happen, we’ll need to know more about its atmosphere — including finding any telltale tracers for life. The planet’s star is very much like our Sun, and in the grand scheme of things, since life evolved to take advantage of what the Sun has to offer, it will be interesting to find out, someday in the distant future, what sort of life Kepler-452b has got on its surface.

All of us who read science fiction know about the countless worlds that populate the stories we read. Many times they ARE Earth-like, but supporting entirely different forms of life than what we have here. That makes sense — the universe is the ultimate generator of infinite diversity in infinite combinations. The boundary conditions — that is, the starting collection of compounds from which life can arise — may well be slightly different from what we know here on Earth. Or, it could be a LOT different. And those differences all but guarantee that life elsewhere isn’t going to look like us.

But, it’s fun to think about life elsewhere as we gaze at a starlit sky, or browse through the artist’s concepts of worlds that Kepler and its partner observatories have found. That’s the sort of stuff that keeps us going, striving to explore ever further out in the galaxy. It’s what we do.

astronomy, exoplanets, Kepler mission, Kepler-7b, spitzer space telescope

Exoplanet Cloud Atlas

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Patchy Clouds on a Distant World

Even though it’s not doing any more planet-searching due to an equipment failure, the Kepler telescope (along with the Spitzer Space Telescope) have returned data about a distant exoplanet called Kepler-7b that show it has clouds in its atmosphere. The data allowed astronomers to create an atlas of cloud forms over this planet, ranging from high clouds and clear skies in the western to somewhat clearer regions elsewhere. This is the first time that a “reflective signature” (that is, data that indicate reflectivity of an object in space) has been seen.

Kepler-7b (left), which is 1.5 times the radius of Jupiter (right), is the first exoplanet to have its clouds mapped. The cloud map was produced using data from NASA's Kepler and Spitzer space telescopes. Image credit: NASA/JPL-Caltech/MIT
Kepler-7b (left), which is 1.5 times the radius of Jupiter (right), is the first exoplanet to have its clouds mapped. The cloud map was produced using data from NASA’s Kepler and Spitzer space telescopes. Image credit: NASA/JPL-Caltech/MIT

Kepler-7b planet radiates much more heat than most giant planets that Kepler scientists have found and its reflectance definitely implies clouds. It lies much too far away from its star to account for the light scientists see being reflected by the planet. That almost certainly suggest that there are clouds floating in this world’s upper atmosphere.

During its mission, Kepler identified planets by fixing its gaze at a specific point in the sky and watching for dips in starlight that occur as the planets transit, or pass in front of their stars, blocking the light. This technique and other observations of Kepler-7b previously revealed that it is one of the puffiest planets known. If it could somehow be placed in a tub of water, it would float. The planet was also found to whip around its star in slightly less than five days, giving it a very short year.

Kepler’s partner in the observations of Kepler-7b, the Spitzer Space Telescope, can focus on one part of the sky for long periods of time, just as Kepler was designed to do. Spitzer is sensitive to infrared light which means it can “see” the heat coming from a distant object and take its temperature. During its observation, Kepler detected a temperature for Kepler-7b somewhere between 1,500 and 1,800 degrees Fahrenheit. Much hotter than most household ovens.

Using the two of these telescopes together to observe distant worlds gives astronomers a new way to study planets that lie far away circling other stars. It also allows astronomers to fine-tune their search for clouds on smaller, Earth-like worlds. (If you’re interested in more details you can read more about this discovery here.)

Now that Kepler is no longer actively looking for planets, scientists are turning their attention to the immense amount of data Kepler sent back, and using telescopes such as Spitzer (and ground-based instruments) to do observations on already known planet candidates.

I find it amazing that we can see these clouds on such a distant world (it lies trillions of miles from Earth). But, I find really impressive is that even though Spitzer can no longer do the most sensitive observations (due to its losing its instrument coolant), it can definitely still show us some amazing things in the cosmos. There are many more planet candidates discovered by Kepler that scientists will be studying, so look for more Kepler-based announcements in the foreseeable future.