Hunt for alien life zooms in on newly discovered solar system

HARI SREENIVASAN: Now to this week's edition of Leading Edge.

There is new excitement tonight about the search for possible life in a solar system beyond our own. Astronomers have identified seven Earth-sized planets orbiting a star just a mere 230 trillion miles or so from our own planet. That sounds like a mind-boggling distance. It is. But researchers say the idea of life on one of these exoplanets, as they're called, is tantalizing.

Astronomers, using ground and space telescopes operated by NASA and the European Southern Observatory, made the announcement.

Our own Miles O'Brien is here to guide us through the news.

First of all, if something is so far away — this is maybe a basic science question — how do we know what we know and what we saw?

MILES O'BRIEN: It's a good question.

You know, think about it for a minute. If it's trillions of miles away, how is it even possible? So, imagine — the technique is called transit photometry. Now, imagine you're about a mile away from a headlight and a mosquito goes across the headlight.

Believe it not, that headlight is slightly dimmed by the fact that that mosquito goes across. Well, this is tantamount to what they do. The planet goes in front of the star, it dims ever so slightly, and with a lot of complicated and sensitive instrumentation, you can determine that, in fact, that's a planet.

They discovered three of them this way. They said, hmm, this is an interesting, ultra-cool brown dwarf to look at. Let's put some more hardware on it. They set more instrumentation on it. And, sure enough, there ended up to be seven Earth-like planets, just about the size and mass of Earth, orbiting this Jupiter-sized, ultra-cool brown dwarf.

HARI SREENIVASAN: Now, you say ultra-cool, that doesn't mean it's a cold sun. It's just not as big or as hot as ours, right?

MILES O'BRIEN: It's about like Jupiter is to us, OK, cooler and smaller.

HARI SREENIVASAN: And when we talk about this habitable zone, this Goldilocks, not too cold, not too hot, how do they know that there are planets in this group that exist within that range?

MILES O'BRIEN: They can measure the radiation off of TRAPPIST-1, this particular ultra-cool brown dwarf, and figure out the zone at which water would remain liquid. And that's the key.

Everywhere we look on this planet and we find liquid water, we find life. It doesn't matter where we go. So, in the hunt for potential alien life, the thought of finding places where there is liquid water is what really intrigues scientists.

So, these planets are a lot closer to TRAPPIST-1 than we are to our son, but, remember, it's smaller and dimmer. And they have these very tight little orbits. And it's quite likely there might be water on some of them.

HARI SREENIVASAN: So, even with just a few weeks that we have been watching this particular system, what do we know about what it would be like to stand on one of these perhaps rocky, inhabitable planets?

MILES O'BRIEN: It would be a very interesting place.

For one thing, we believe they are tidal-locked, which means — it's like our moon facing us. We only see one side of the moon as it orbits around. These planets face their star all the time. So you have got a sunny side and you have got a nighttime side.

So, if you're buying real estate, I would go on the sunny side of one of these planets, for sure.


MILES O'BRIEN: If you were to stand there, you would see probably kind of almost perpetual sunset kind of idea. And these other planets would be perhaps larger than our moon in the sky. It would be a very interesting place to be.

HARI SREENIVASAN: And it wouldn't take 365 days to go around. These things are spinning around…



MILES O'BRIEN: No, no, the one closest in is about a day-and-a-half around. The one farthest out, they think about 20 days.

So, if you are going to live out there, you are going to get old quickly.

HARI SREENIVASAN: So, this is just the first little look that we had. And scientists love to start to point every other piece of technology they have.

What do we hope to learn with perhaps the satellites that are coming up?

MILES O'BRIEN: Well, exoplanet researchers are very excited about this. As a matter of fact, they're deploying existing instrumentation on it.

Let's listen briefly to Sara Seager, who is an exoplanet researcher at MIT.

SARA SEAGER, Massachusetts Institute of Technology: The great news is we can observe in the near future. We no longer have to rely on what we think and speculation, because nature usually is smarter we are. And if there is any way for life to get a foothold, we like to believe it will.

HARI SREENIVASAN: This is like the Super Bowl for exoplanet researchers. Right?

MILES O'BRIEN: It is indeed.

And we're looking ahead toward a big improvement in the space-based telescope capability. The James Webb Space Telescope, long delayed, overbudget NASA project, is finally slated for launch in October of 2018.

It will have spectroscopy equipment on it, which means it will be able to analyze the atmosphere of these planets and identify some of the key building blocks of life, whether it's oxygen, or hydrogen, or methane or carbon, and make some determination as to whether it is even more likely that there is potential life on some of these planets.

HARI SREENIVASAN: All right, Miles O'Brien, thanks for joining us.

MILES O'BRIEN: You're welcome, Hari.

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