Category Archives: planets

extrasolar planets, planets

Tales of Science and Imagination

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A Jupiter-sized planet (artists impression) passing in front of its parent star. The planet was discovered by the NASA/ESA COROT satellite. (Read here for more COROT information.)
A Jupiter-sized planet (artist's impression) passing in front of its parent star. The planet was discovered by the NASA/ESA COROT satellite. (Read here for more COROT information.)

Exoplanets are grabbing the headlines these days. There are something around 220 or so planets around other stars that we about, and the number keeps growing as astronomers refine their planet-searching techniques and upgrade specialized telescopes to do the searches. There have been several discoveries announced in recent weeks, and at least one more that I know of will be announced soon. So, there’s a bonanza in planet discoveries going on.

One of these days we’ll find an Earth-like planet and know it’s an Earth-like planet (we think we’ve found one, but the “Earth-like” part is still unconfirmed). That’ll set off a huge firestorm of discussion about what life might be like on such a world. Of course, for science fiction readers, such discussion topics are old hat, but as an SF reader myself, I suspect that the reality of an Earth-like planet and its life will probably be nothing at all like what we’ve imagined in SF magazines and books for the better part of a century now.

When I was a kid, I used to imagine going to Mars and finding life there. I didn’t know about the Edgar Rice Burroughs “life” on Mars until I was much older, so my childish imaginings were not limited to fighting men and princesses. Most of the time I was finding strange red plants, weird talking worms, rabbits, etc. I guess the life I imagined was what was familiar to me as a child. Although, since I lived part of my life on a farm, I don’t recall imagining Martian sheep and cows and chickens.

Life on other planets around other stars didn’t even enter into my world view until I was somewhat older and had read my first science fiction. And, of course, that life was humanoid, water-based, and still somehow weird. Science fiction tales are made up by humans, so it’s pretty obvious that our stories of alien life will have some attributes of humanity, no matter how that life looks. I suspect that’s because if somebody came up with a truly weird life form, the story would founder along until one of the characters found a way to communicate with it. (Shades of Star Trek, and the many ways Hollywood tried to imagine the truly weird and talk to it.)

So, SF fan that I am, I can’t wait til the first life-bearing planet outside our solar system is found. The debates and discussions are going to be amazing to witness and take part in!

dwarf planets, planetary science, planets, sedna

Building Sedna

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sedna
An artist’s conception of Sedna, a dwarf planet in the Kuiper Belt. Credit: NASA/JPL-Caltech

Remember a year or so back when the largest Kuiper Belt Object to date, named Sedna, was discovered? It shifted planetary scientists’ attention to the origin and evolution (and existence!) of large, planetoid-sized objects out beyond Pluto. They’ve been working out the fine details of Sedna’s orbit for a while now, using sophisticated models of the early solar system formation. One of the outcomes of this work is the idea that this nearly-Pluto-sized “worldlet” actually formed in place in the frigid deep-freeze of the outermost solar system. Originally scientists thought it was assembled farther in toward the Sun during the early days of the system’s formation, and was somehow ejected out to its current position.
Why does where Sedna formed matter? Astronomers have longed assumed that planetary formation took place in a rather smaller region of the original solar nebula. If Sedna was created from the collisions of smaller bodies out in the “sticks” of the solar system, then the planetary factory is bigger than everybody suspected. It also means that the Kuiper Belt, which hosts countless bodies at what used to be called “the edge of the solar system” is really part of a larger region called the Kuiper disk and played a much more prominent role in the formation of planets and moons.
The modeling that led to these conclusions was done at the Southwest Research Institute in Boulder, Colorado. In the press release they sent out announcing this work, the institute’s Executive Director for Space Studies, Alan Stern (a former colleague of mine from the University of Colorado), talked about some of the assumptions they made in constructing their model: “”The Sedna formation simulations assumed that the primordial solar nebula was a disk about the size of those observed around many nearby middle-aged stars — like the well-known example of the 1,500-AU-wide disk around the star Beta Pictoris.”
It’s interesting work because it gives us a whole lot MORE insight into the infancy of our own solar system, in particular the formation of planets from smaller planetesimals. And, chances are if Sedna formed where the astronomers think it did, then there could well be more large planetoids circling around out there with it — and that what we used to think of as the “emptiness of the outer solar system” isn’t so empty anymore. As astronomers learn more about the Sun’s outermost retinue of planetesimals, they are finding more clues to what conditions were like early in the history of solar system.