February 23, 2012
Astronomers announced this week that they’ve confirmed the existence of a new class of planet — a hot, watery, exotic “super-Earth.”
A little over two years ago, astronomers at the Harvard-Smithsonian Center for Astrophysics discovered an exoplanet that we agreed was worth some extra attention. The planet, designated GJ 1214b, is only 2.7 times the diameter of Earth — one of the smallest exoplanets found — and orbits just over a million miles from its star (compare to Earth’s 92 million miles) in a zippy 38-hour ‘year.’
Given its size and density, astronomers speculated that GJ 1214b may very well be covered in deep oceans. The Harvard-Smithsonian team kept studying it, enlisting the Hubble Space Telescope to get more data about the planet’s atmosphere. “We’re using Hubble to measure the infrared color of sunset on this world,” said astronomer Zachory Berta in this week’s release. The data seem to confirm that GJ 1214b has a very steamy atmosphere, thick with water vapor.
Even more intriguing is that due to the temperature (being so close to its red dwarf star makes it around 450 degrees Fahrenheit) and extreme pressures, all that water gets a bit…exotic. Materials “like ‘hot ice’ or ‘superfluid water’ – substances that are completely alien to our everyday experience” would form, according to Berta. We emailed Berta to ask if he could explain these strange materials further.
Frankly, it’s difficult for me to imagine what these exotic forms of water would be like – we have very little experience with them here on Earth. They’re simply how the molecule H2O acts when it is in high pressure and temperature environments …
Our closest point of comparison is that the outer atmosphere might be something like a hot, steamy oven that you would use to bake bread with nice crust. But as you go deeper into the planet, you would encounter these exotic forms of water. I should add, however, that there’s still an enormous uncertainty about the composition of the planet overall. Yes, the observations point to a planet that is rich in water, but what is it mixed with, and in what proportions? Really visualizing the “surface” of this planet (if there is one!) will require us figuring those things out!
But whatever the case, the temperatures are too high for liquid water as we know it to exist on GJ1214b.
We feel obligated to point out that if you’re going to google “hot ice” like we did, the first hit you get is this video; we asked Berta if that’s what he was talking about. He replied, “Sadly, I don’t think the YouTube video would be a great example. It shows water that’s saturated with sodium acetate, and the sodium acetate is crystalizing into the solid form. I’d really rather you didn’t link to it [ed note -- Sorry!], because that’s not what we think is going on.” OK, we crossed it off our “What Hot Ice Might Be Like” list.
Given the existence of water, we also asked Berta if he would “speculate wildly” on the question of life on GJ 1214b:
There’s probably no liquid water anywhere on this planet, so nope, I won’t speculate wildly about what sort of life could live there. Sorry! I can’t imagine it – the temperature would be too high for the large, complex molecules that make life possible to survive. But I will say this, which I think is an important point along the same lines:
What makes me excited about these observations is really the technique, the idea that we can use a telescope to observe the atmosphere of a very distant planet. GJ1214b is too hot for life, but it’s not too difficult for us to imagine that we could make similar observations of the atmosphere of a planet that was a little cooler in temperature than GJ1214b and could potentially host life. Microbial and plant life on Earth have dramatically altered our atmosphere over its history. If they did the same on another planet orbiting another star, observations like these of that planet’s atmosphere might then be able to tell us whether or not there is life elsewhere in our galaxy.