Sizzling Newborns Easier to Spot
When you’re an astronomer looking for Earth-like planets around other stars, you might strike pay dirt among newly formed planets. Such baby rocky worlds come out of the planetary system birth process with hot, molten surfaces. As it turns out, an astronomy team equipped with instruments sensitive to that glow could pick it out entirely separately from the glow of the bright nearby parent star.
At the Division of Planetary Sciences meeting in Ithaca, New York this week, MIT planetary scientist Linda Elkins-Tanton discussed the possibilities for discovering new worlds not long after they’re born. It’s all a matter of catching them at the right time, while they’re still giving off that after-birth glow.
For a few million years after their initial formation, Earth-like planets (i.e. made of rock) may be slathered with a surface magma ocean (think: molten rock) that would glow brightly enough to make them stand out as they orbit neighboring stars.
Elkins-Tanton suggests that the “magma ocean” stage for Earth-sized planets may last a few million years, much longer than previously estimated. What’s more, even after the surface solidifies, it could stay hot enough to provide an infrared glow for more than 10 million years.
The big problem for astronomers hoping to detect planets around other stars is that there’s a huge difference in brightness between the star and a planet. The planet shines only by reflecting light from its parent star and the planet is pretty tiny compared to the relative monstrosity of a star. Just look at the relative sizes of the Sun and the terrestrial planets of our own solar system and you’ll see what I mean.
But, when the planet is relatively young and still has a molten surface, or is in its cooling-down stage, the difference in brightness in infrared wavelengths for a glowing, molten planetary surface would be much less.
If you knew what to look for, you could tell the difference between the star and the planet. Elkins-Tanton’s work suggests a neat new way that astronomers using future high-resolution instruments will be able to spot and identify newborn Earth-like planets. This, in turn, will help them understand just how long planetary surfaces stay molten, how long they take to cool down, and give them some surprising insights into the heating sources and surface evolution processes that make rocky planets. What’s really interesting is that watching this process on newborn Earth-like worlds will also help us understand what our own home planet was like during its babyhood.
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Planetarium Hoo-rah Update: I received some notes from folks today about the last of the presidential debates here in the U.S. and the continuing misstatement of the McCain campaign about the Adler Planetarium’s projector. At this point, I’m not inclined to blog about it again, since I and many others have already pointed out publicly the flaws and errors in the McCain campaign’s reasoning and fact-checking. Please visit my previous postings (and links to other posters) to see for yourself what the hoo-rah is all about. Just for the heck of it I created a t-shirt and mug over at my CafePress store (see left sidebar). Check ’em out!
Also, if you haven’t registered to vote and there’s still time, please do register–no matter who you support.