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Kepler scientists find freaky solar system that's unlike anything we've seen before

Illustration for article titled Kepler scientists find freaky solar system thats unlike anything weve seen before

NASA scientists working on the Kepler Mission have discovered an unprecedented solar system, in which two planets with vastly different densities and compositions are locked in a surprisingly close orbit around their star. The finding shows that there is much greater diversity in the composition of solar systems than we'd previously thought.

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Prior to our discovery of exoplanets, our solar system offered a standard blueprint for astronomers speculating about what other solar systems might look like — namely, rocky planets on the inside, and large gas giants farther out. Then, with the discovery of enormous inner-system gas giants, our conceptions of what other systems might look like took a drastic turn. And now, with the discovery of these two new exoplanets, our imaginations are proving to be completely inadequate.

Illustration for article titled Kepler scientists find freaky solar system thats unlike anything weve seen before
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This newly discovered system is called Kepler-36, and it's about 1,200 light years away. One of its planets is a rocky super-Earth about 1.5 times the size of our planet and 4.5 times the mass. Its companion, a Neptune-like gaseous planet, is 3.7 times the size of Earth and eight times the mass. And they're very close to each other – about 30 times closer than any pair of planets in our solar system.

Because their orbital distance varies by only 10%, the view of the Neptune-like planet from the rocky planet must at times be pretty spectacular.

The new solar system, which the Kepler scientists describe as "extreme," will likely have an impact on emerging theories about planet migration and orbital rearrangement. Prior to this discovery, scientists had assumed that small, rocky planets form in the hot part of the inner solar system, and that bigger, less dense planets can only form far away from the host star, where it's cool enough for volatile material like water ice and methane ice to collect. And it's thought that, in some cases, gas giants can slowly creep their way into the inner solar system, annihilating or ejecting the low-mass inner planets.

But the discovery of Kepler-36 messes this all up, sending the scientists straight back to the drawing board. Specifically, astronomers will have to figure out how the two planets with such different densities in nearly identical orbits both got there and survived — a configuration the Kepler team described as "puzzling."

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Be sure to check out the entire study, titled "Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities".

Top image via Shutterstock.com/HomeArt. Artistic impression of Kepler-36 by David Aguilar, Harvard-Smithsonian Center for Astrophysics.

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DISCUSSION

Wait, if they're that close, aren't they closer to a planet-satellite (like Terra and Luna) or dual planet system (like Pluto and Charon) than two separate planets?

30 times closer than any two planets in our solar system would be 1/30 of 0.3 AU (the approximate distance between both Mercury and Venus or Venus and Terra), which comes out to 1.5 x 10^6 km, which is only about 4 times the distance between Terra and Luna (3.8 x 10^5 km). Given that the larger planet is roughly half the mass of Neptune, wouldn't that be close enough to rule the two into occupying a single system of movement?

In other words, if I'm reading this correctly the two planets appear to share the same orbit rather than unusually close separate ones. So it seems plausible to me that the smaller planet is either a captured satellite or an object that formed from accretion around the larger one. If so, the big news here isn't that this throws our understanding of planetary formation into the blender, but rather that we have the first example of a popular science fiction concept: a Terra-sized (roughly) moon orbiting a gas giant.

Y'know, like Yavin 4. Or Pandora.