Where is Planet B?

2 03 2010

NASA - Best Picture of Earth ever (from Goddard's Photo and Video Blog)Today’s photomontage from NASA “The Best Picture of Earth Ever” (linked image to right) is a great segue into this post. I’m writing an article for Alternatives Journal for their upcoming “Out of the Box” issue. The focus of the article is planets around other stars — can they help us appreciate what we have here? If the Earth is the only planet in our galaxy with intelligent life, we all have an immense responsibility.

During editting I’ve had to take some material out — namely that about SETI, the search for extra terrestrial intelligence. Here’s the “outtake”…


You might be wondering why I haven’t talked about SETI – the search for extraterrestrial intelligence. The main issue with SETI is that it is just incredibly hard.

Some people may remember the movie “Contact” with Jodie Foster, which was actually a novel penned by the late Carl Sagan. After years of traveling through space, our radio transmissions from the 1930s eventually reach an alien planet. The movie aliens detect them and send a return signal back to us with a message encoded.

This is based on real science, well at least the radio transmission part. Our radio signals from decades ago are heading out into the galaxy. There’s nothing we can do to stop those signals. They left too long ago. So if anyone is listening, we’re telling them we’re here.

But is there anything coming here? Are any episodes of an alien “I Love Lucy” heading toward us? Possibly. The difficulty is that the signals are incredibly weak and our galaxy isn’t a “radio quiet” place. Even the enormous “Square Kilometer Array” (SKA) radio telescope, likely to be built in Western Australia around 2020, will only be able to detect these kind of transmissions out to a few light years away. Frankly, we really don’t expect to find many intelligent civilizations that close.

But a couple of possibilities mean things aren’t quite as bleak as you might expect. The radars used by airports are incredibly powerful. The SKA can detect these radars up to about 100 light years away. So if there is another advanced civilization within 100 light years chances are we might well detect their radars. But even within 100 light years, that’s still only about a million stars, and the odds still aren’t that great. To put that tiny fraction in perspective, the galaxy contains 400 billion stars, and is about 100,000 light years across.

What we really need to find are some gregarious aliens. If they chose to deliberately send a signal to us – as we have done on at least two occasions – then we could detect that. It’s true for virtually any place in the galaxy. That is what SETI searches are actually looking for. But the problem is the aliens have to want to tell us they’re there. I don’t know about you, but I’m still slightly concerned about advertising our existence. Wouldn’t other civilizations be equally worried?

In a way, I find the thought there might be other civilizations out there strangely comforting. The idea we might be the only intelligent life in our galaxy is scary. If that’s true, our planet is very special. More special than we had ever anticipated.


The SKA is an incredible project that scientists around the world are really excited about. It’s also an incredibly expensive telescope (billions of dollars) but the payoffs are huge. Who knows what we might be talking about in 15 years time?

Did ET phone home? 🙂

Next posting: How language and rhetoric can shape public perceptions on environment and science.




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