Water World

Now, if you’ve just seen the title of this post, you might be thinking it was concerning the film “Water World” starring Kevin Costner, but that isn’t the case here. If you’re into astronomy then this post is certainly for you.

Scientists have apparently discovered a new type of planet — a steamy water-world if you will, that is larger than the planet Earth but smaller than Uranus. … that’s right, get your laughs in while you can.

The standard-bearer for this new class of exoplanet or extrasolar planet is called GJ 1214b, which was first discovered by astronomers in December of 09. New observations by NASA’s Hubble Space Telescope suggest that GJ 1214b is a watery world blanketed by a thick, steam-like atmosphere. “GJ 1214b is like no planet we know of,” study lead author Zachory Berta of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said in a statement. “A huge fraction of its mass is made up of water.”

To date, astronomers have discovered more than approximately 700 planets beyond our own solar system, with about 2,300 more planet “candidates” awaiting confirmation. These planets are incredibly diverse. Astronomers have found one planet to be as light and airy as Styrofoam, and another as dense as iron for example. They’ve discovered several worlds that orbit two suns, reminiscent of something right out of science fiction movies.

GJ 1214b though, which is located 40 light-years from Earth in the constellation Ophiuchus (The Serpent Bearer), is “something new altogether”, said researchers. This super-earth of a planet is about 2.7 x Earth’s diameter and weighs nearly seven times as much. It orbits a red-dwarf star at a distance of 1.2 million miles (2 million kilometres), giving it an estimated surface temperature of about 446 degrees Fahrenheit (230 degrees Celsius), certainly too hot to sustain life, as we know it at least.

Scientists first reported in 2010 that GJ 1214b’s atmosphere is likely composed primarily of water, but their findings were not definitive. Berta and his team used Hubble’s Wide Field Camera 3 to help dispel any of their doubts. Hubble watched as GJ 1214b crossed in front of its host star, and the scientists were able to determine the composition of the planet’s atmosphere based on how it filtered the starlight. “We’re using Hubble to measure the infrared color of sunset on this world,” Berta said. “The Hubble measurements really tip the balance in favor of a steamy atmosphere.” Berta and his colleagues’ results are reported online in the Astrophysical Journal.

Since astronomers know GJ 1241b’s mass and size, they’re able to calculate its density, which turns out to be just 2 grams per cubic centimeter (g/cc). Earth’s density is 5.5 g/cc, while that of water is 1 g/cc.GJ 1214b thus appears to have much more water than Earth does, and much less rock. The alien planet’s interior structure is likely quite different from that of our world. “The high temperatures and high pressures would form exotic materials like ‘hot ice’ or ‘superfluid water,’ substances that are completely alien to our everyday experience,” Berta said.

GJ 1214b probably formed farther out from its star, where water ice was plentiful, and then migrated in to its current location long ago. In the process, it would have experienced more Earth-like temperatures, but how long this benign phase lasted is unknown, researchers said. Being that GJ 1214b is so close to us, it’s logically a prime candidate for study in the near or not so near future. NASA’s James Webb Space Telescope, which is supposed to launch some time in 2018, may be able to get an even better look at the planet’s atmosphere, according to researchers.

 

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3 comments on “Water World

  1. Wow! Interesting stuff. I wonder if it can possibly be as uniform as the diagram suggests, or if there might be small islands – although looking at the suggested depth of water, perhaps not!
    Thanks for posting this. 🙂

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