The astrophysicist who discovered Zarmina describes life on "second Earth"

Steve Vogt is the UC Santa Cruz astrophysicist who discovered Zarmina, the first recorded Earthlike planet outside our solar system. He told io9 what a human colony there would be like, and why he believes the planet already harbors life.

Image by David Hardy

I spoke to Vogt at his home in Santa Cruz by phone last night. The planet's official name is Gliese 581g, but Vogt has nicknamed it Zarmina, which is his wife's name.

io9: You've said in interviews that you're sure there's life on the planet. Why do you believe that?

The astrophysicist who discovered Zarmina describes life on "second Earth"

SV: Somebody asked me my opinion, and I gave it. I've actually received a lot of criticism for saying that, as if I'm a bad scientist for stating what I believe. I don't have any facts that prove anything like that - I just have my opinions. It's hard to make this obvious in a soundbite but the universe is a vast place and most of it is totally unavailable for life as we know it. There are two things in the universe you can't get around: Temperature and gravity. So if you are in interstellar space you're at 2.7 degrees kelvin. Your atoms are hardly vibrating and you're not going to be alive. Life as we know it can't survive. So you have to be near a star. That's good, but stars have gravity and you can fall into them. Your only hope is to be near a star but not falling into it – you need an orbit. And that's magical. That's where you can have enough warmth, but not turn into a cloud of plasma because you've fallen into the star. So when you have a planet in orbit and it's the right size and in the right orbit [like Zarmina], it's a very special place. There are many planets like that but we didn't know that [until our discovery].

I'm not an expert in biology but when you read about the conditions under which life took hold on this planet – it was a terrible place 4 billion years ago, with no oxygen. Yet life came on the scene quickly. Something hit Earth so hard it broke off a chunk that created the Moon. And yet life kept coming back over and over again. You learn from that that it's hard to stop life.

So when I look at a place like this planet, with strong gravity and a good temperature – all those conditions are just perfect. It would be easier for life to evolve on that planet than on Earth. So, heck I'm pretty sure there's life there. Maybe you won't be filming Corona commercials on the beach there but it will be life.

The astrophysicist who discovered Zarmina describes life on "second Earth"

Diagram by Athena Andreadis

Why do we assume that you need to have an Earthlike planet with liquid water to sustain life? Why not life on a Super Earth or a gas giant?

It depends on what you mean by life. Sure, you can imagine gas clouds that are alive. But we're talking about what we would recognize as life. It comes down to whether you could you make a hamburger out of it, or it could make one out of you. Life as we know it requires organic chemistry, which requires liquid water. But sure, if you had some other form which is made of silicon circuits that's different.

So this planet is bigger and more massive than Earth. Would the gravity there be too much for a human colony?

That's what's interesting – the gravity wouldn't be too much. It's three to four times the mass of Earth but 20-50% bigger. So there's more real estate there. The gravity would feel very similar to Earth - you'd be about 1 G or 1.5 Gs heavier. You wouldn't be too shocked, though you might feel heavy enough to sign up for Jenny Craig. You could stand up and walk around - you wouldn't need to crawl. 2 or 3 Gs is tough, but this is just a little bit stronger gravity than the Earth. That's a good thing because it means there's less chance of the atmosphere escaping. You need atmosphere so that water can have enough pressure to stay in liquid state. On Mars, for example, the atmosphere is so thin that water can't remain liquid.

The astrophysicist who discovered Zarmina describes life on "second Earth"

What about the weather on this planet? It's tidally locked, which means one side always faces the sun and one side is always in darkness. Wouldn't there be incredibly strong winds moving from the hot side to the cold side?

People thought there'd be hellacious winds. But there have been 3D climate models of tidally locked planets and calculations show there would be high altitude winds like jet streams on our planet. But according to these models, the maximum winds on the surface would be 30-40 miles per hour on the hot side. On the dark side, winds would be 0-10 miles per hour. It would be quite pleasant. The winds would carry heat from the hot side to the cold side in the high altitudes and then the cold winds would come back down over the poles. The winds would circulate on a large scale like on Earth and that would even out the temperature somewhat. Some of that depends on whether it's covered by oceans or continents.

The astrophysicist who discovered Zarmina describes life on "second Earth"


Image by David Hardy

Can't you use spectrometry to figure out if there are oceans?

We can't resolve that question using conventional technology just from the light of its star. The planet doesn't transit the star, so we don't have a chance to see it. [Editor's note: When planets transit a star, astronomers can use spectrometry to see light moving through a planet's atmosphere, and determine the chemical composition of its surface].

Given the planet's temperature, where would be a good spot to put a colony?

The terminator is the line between light and dark and that would be where it's most comfortable. Along the terminator you'd want to be down near the equator because the poles would be pretty cold. So you'd look to the intermediate to low latitudes near the equator. The sun would sit constantly on horizon. You could tune your temperature by moving towards the day or the dark until you were comfy. The temperatures there might be anything between 160 F to -20. There would be lots of regions around the terminator that have different temperatures. We'd pick an equatorial area that's warmer like Mexico or Equador. You'd be able to stand outside in your shirtsleeves. It might be tropical. And if you wanted a different temperature, you'd move your longitude.

The astrophysicist who discovered Zarmina describes life on "second Earth"

Are you working on locating other Earthlike planets? Where's the next likely target?

Absolutely. This is just one of many systems we're tracking [at Keck Observatory]. We have a 1500 star target list. We're focusing on the 400 nearest ones. I expect we'll be finding more Earthlike planets. Mainly we're looking at red dwarf stars - those have highest priority. The top priorities for us are the nearest red dwarfs that have hints of planets or are quiet. It's not really clear which will pop next.