On Wednesday, the scientists at NASA kind of freaked out. They announced the discovery of some seemingly Earth-like planets outside of our solar system, a group of rocky globes they’re calling ‘TRAPPIST-1.’
How far away are these newly-discovered worlds? They’re about 40 light years from Earth. That means using today’s rocket technology (and a whole lot of cash), it would probably take about 11,250 years to get to TRAPPIST-1.
I called up one of NASA’s exoplanet experts, Aki Roberge, to help us break down the find. A specialist in planet formation, Roberge helps plan future missions for NASA, and confirms that the space agency nerds are just about “as excited as we get” about TRAPPIST-1.
Q: Why Are Scientists Freaking Out About TRAPPIST-1?
Roberge: To be completely blunt, the most exiting thing for actual scientists is that these planets are close enough that we’re actually going to be able to study them – particularly when the James Webb Space Telescope launches (October 2018.) When that launches, it will have a real shot at actually taking a look at the atmospheres of these planets – or if they have atmospheres at all. So it’s like a promise of future excitement, in some ways.
I can see why people would think this is more of the same stuff [NASA’s] already been doing. And in some aspects, it is. But it’s a smaller star, it’s closer to us, and it’s got more planets – really tightly packed. The closer the system is to our solar system – the more the star is like the Sun and the planet is like the Earth, the more likely we are to understand what we’re looking at. That’s what makes it exciting.
Q: Why is everyone calling these planets ”Earth-like?’
Roberge: At the moment, all you really tell from the transits is these are small black dots. We just get a radius – and if we’re super lucky – as they were in the case of this system, they can get masses. The sizes and masses of these planets is really valuable information though, because it does suggests that most of them are rocky. Six of the seven planets look like they’re rocky. And being Earth-sized, we think it’s a good place: an atmosphere thick enough to keep you warm and last for billions of years, but not so thick that you end up being a gas giant planet.
There are, however, several reasons to think that being a rock in the habitable zone of a red dwarf star is not actually a nice place to live, and that those environments are very different from our solar system. A lot of these investigations that are going forward over the next decade are to find the answers to these questions.
Q: Is there water on the surface of these planets?
Roberge: Most of them are the right distance from a star that maybe they could have liquid water on their surfaces. But that’s a huge maybe. Just look at our solar system: we have three rocky planets – about the size of the TRAPPIST-1 planets. We’ve got Earth, Venus and Mars in or near what astronomers call the “habitable zone” – and they couldn’t be more different!
Q: What’s the big deal about ‘rocky’ planets?
Roberge: As far as we know, that’s the only kind of planet that we could have habitable conditions of life on – life that we could actually understand or recognize from interstellar distances. The Earth is unique in the solar system in one really important way: it’s the only planet that has surface life so abundant that it’s affecting the atmosphere. That is noticeable from interstellar distances. So it’s not really that we think Earth-like life is the only life that can be out there. It’s just the only life we can detect.
Q: What can non-scientists get excited about here?
I think this would really bring it home to people that we have neighbors. I think a lot of people are used to thinking “oh, exoplanets, those are all really distant.” As far as the laws of physics go, you could get to TRAPPIST-1 in a human lifetime (~40 years) [But, again, as stated earlier, with toaday’s technology it would probably take about 11,250 years to get to TRAPPIST-1. Hense, the ‘so what’? sentiment. Surely, we can learn to live on this wonderful planet–or not–by then]. So it becomes more of an engineering problem than a laws of physics problem.
Editor’s Note: Questions and answers have been edited for length and clarity.
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