Goldilocks, and other Habitable Zones for Life

Heard of the Goldilocks zone?

It’s the idea that an area of space around a star will be at the right temperature for life to exist. Not too hot, not too cold, hence Goldilocks.

It’s a bit like standing around a campfire on a very cold night. Stand too far away and you freeze, stand too close and you catch on fire and burn to death.

It’s the same with planets orbiting stars too, if they’re too far away then water freezes and life can’t emerge, and if they orbit too close the planet is roasting hot and nothing can live.

It gets a bit more complex than this though, but complex in a fun way. Oh and its also got some pretty big implications for the search for extraterrestrial life…

Life in our Solar System – Mars

In this series of posts I’ve looked at planetary bodies in our Solar System that could support life, from the moons of Saturn and Jupiter, to the cloud layers of Jupiter itself, to the ephemeral-once-jungles of Venus, I’ve even looked at Earth itself.

Now one of my favourites, Mars, the Red Planet.

Life in our Solar System – Earth

In previous posts I’ve looked at some likely, and some less likely, candidates for planets or moons in our solar system that could harbour life, including Jupiter, three of it’s moons, two of Saturn’s moons, and Mars and Venus.

Now its time for Earth. Yep, you read right.

In 1990 NASA used the Galileo spacecraft to look for life on Earth. Why bother you scream, whilst hurling your cup of tea violently against the wall? Well, NASA did it to test how well spacecraft like Galileo can find life on planets and moons from space. Call it a proof of concept, if NASA can find life on Earth, then at least they know the tech works, and hopefully won’t miss signs of life on other planets.

Here’s what they found on Earth:

Life in our Solar System – Venus

In previous posts I’ve looked at the possibility that alien life could be found in our solar system, on three of Jupiter’s moons, in Jupiter itself, and on two of Saturn’s moons.

This time we’re moving nearer to home, to the planet closest to our own, Venus, the second rock from the Sun.

Life in our Solar System – Titan and Enceladus

In a couple of previous posts I looked at the possibility of life existing on some of Jupiter’s moons, including Europa, and then the possibility of life existing on Jupiter itself.

In this post we’ll head further out into the solar system and look at two of Saturn’s moons, Enceladus and Titan.

Life in our Solar System – Jupiter

In a previous post I talked about the possibility of life existing on, or in, some of the moons of Jupiter, with Europa being the best candidate.

But how about life existing within Jupiter itself?

Life in our Solar System – Europa, Ganymede & Callisto

Astrobiology is all about finding alien life, and many astrobiologists believe life could be found in our Solar System, on Mars, on moons like Titan, Europa or Enceladus, and potentially on other bodies, like Kuiper Belt Objects.

In this post I’ll look at why some scientists think life may exist on Europa, and maybe even Ganymede and Callisto too, three of Jupiter’s largest moons.

So what’s so special about theses ice worlds?

The Open University, a different way to study.

OK, this post is going to be an unabashed advertisement for the Open University. I don’t work for them, I’m not doing this for any personal gain, I’m doing it because I’m a student at the OU (I’m working towards a degree in Geosciences), I love it, and I’d like more people to know about it.

If you’ve ever wanted to earn a degree, or just want to study a subject you found interesting, but feel that you can’t attend a traditional university for some reason, be it not enough time or money, or you haven’t got great qualifications from school, or you’re getting on-a-bit and you can’t face all those over-excited teenagers, then the OU may have something for you.

Nick Bostrom on the Fermi Paradox

The Fermi Paradox is an idea that complements the Drake Equation. Enrico Fermi asked the question, if there are so many stars in our Galaxy, and therefore probably many Earth-like planets, then there should be lots of alien civilizations in the Milky Way, but why haven’t we found evidence of them? Why not?

Nick Bostrom talks about the Fermi paradox, and some possible solutions, in the video below. It’s not as smooth as the Carl Sagan clip I just posted, but he has some interesting ideas. Nick Bostrom is a philosopher from Oxford University, and has some interesting ideas on human enhancement, the survivability of advanced civilizations and the nature of reality by the way, his website is full of interesting stuff.

What do you think is the answer? Are we alone? Is there alien life in our Galaxy, but just simple life? Or are advanced alien civilizations doomed to wipe themselves out as they become more technologically advanced?

If you like to read more about the Fermi Paradox, I’ve written a short post here, and a couple of posts on possible solutions here and here.

Carl Sagan on the Drake Equation

Carl Sagan was awesome, he was an American scientist, his interests were pretty broad, he was an astronomer, astrophysicist, cosmologist and astrobiologist, and he was also passionate about teaching science to the general public; he wrote a number of science books and had an award winning TV series called Cosmos: A Personal Voyage. Sadly he died in 1996 aged only 62.

In this video he’s talking about the Drake Equation, the equation used to estimate the number of advanced civilizations in our Galaxy. It’s an awesome concept, and Carl explains it beautifully.

We don’t know the values of most of the variables in the equation yet, particularly the ones towards the end, as Carl demonstrates by calculating an answer between 10 and millions of advanced civilizations, but the Drake Equation is a great way to help us organise our thinking about astrobiology and the search for extraterrestrial life (SETI).

It’s also fun to work out your own answer to the equation based on what you belief the value for each variable should be.

If you want to read more about the Drake Equation I’ve written a short post here.