Monday, July 2, 2012

Just Another Planet

In our group meeting last week, Professor Johnson suggested we calculate how much it would cost to “buy” a planet. So we took a look at how much each detection method tends to cost, by noting its budget and how many planets it has found so far. For all the detection techniques--radial velocity, transits (ground and space based) and TTVs, microlensing, direct imaging--it was estimated that each planet found cost around $100,000.

Wait, $100,000?! For a planet? Why would you spend that much money just to find a planet?!

I don’t know about you, but that was my first reaction. Then I realized, with all the research I’ve been doing, that certainly Galileo and other astronomers of that period would be happy to pay $100,000 (or at least, its equivalent, having adjusted for inflation!) to detect an extrasolar planet. Planets were a big deal! In fact, the very suggestion that other inhabited planets existed got Giordano Bruno burned at the stake! So how have we gotten to this point, where just twenty years ago a new planet was huge news, and now it’s just an everyday event? Why should we be spending this much money on finding planets? Comment below with your thoughts and opinions on this matter, and a follow-up post is coming soon!


  1. Nice post, Lori!

    So who would pay $100,000 for a planet? People in 1994 would have happily paid that much for a single planet. They would have seen it as an absolute bargain.

    [old person]
    When I was your age, there were only 9 planets, all within 75/202265 parsecs!
    [/old person]

    These days I think its appropriate to ask "What kind of planet?" before paying that much. I don't think I'd pay that much for a hot Jupiter, even if it was transiting. But I'd definitely pay that much for a transiting Neptune-sized planet. Especially if it were transiting an M dwarf, like the recently discovered GJ3470.

    $100,000 for a transiting super Earth is a steal! A single RV-detected super Earth might be worth it, but with Minerva we'll buy nearby super Earths in bulk, so they're definitely worth it, especially if one turns out to transit.

    I'd like to see a quick supplemental post showing a couple ways of computing this $100,000 per planet number.

    Keep the posts coming!

  2. Another thing to consider is that no one will really "own" the planet (though if there were ever a prospect of traveling to one of these planets, I'm sure governments use their contributions to the discovery as leverage... But I digress). So it would make sense to distribute the burden equally between all people. Given that there are ~ 7 Gigapeople on Earth, that burden amounts to approximately a thousandth of a penny. Cheap. If we wanted to play that game with just Americans, our cost would be a few hundredths of a penny. Still pretty dang cheap. If things were only that simple...

  3. I think it's a different story if you think of a planet in terms of government spending. For instance, do you think it is more or less expensive to buy a planet or a traffic stoplight? What about an F-22 Raptor figher airplane?

    A stoplight costs 100,000 dollars, about the same as a planet.

    An F-22 Raptor costs 380,000,000,000 dollars, and the government has 200 of them! For the price of just one of these airplanes, we could buy almost 4 million planets!

    Would you rather have a stoplight and get to work 3 minutes faster every day, or would you rather discover a new planet?

    Another way to think of it is in terms of time spent. 100,000 dollars is of the same order of magnitude as a scientist's one year salary. So, can a team of scientists discover lots of planets every year, or do they just skillfully leverage graduate student slave labor?


    1. Whoops, one F-22 raptor costs 380 million dollars, not 380 billion. So for the price of one airplane, you could buy 4 thousand planets.