Friday, July 24, 2009

Fermi Problem Friday

Hurry back guys! Time to head to Pluto.

We recently celebrated the 40th anniversary of the Apollo 11 moon landing, we're airing a special edition of Fermi Problem Friday in honor of Buzz, Neil, and Mike (you know, Michael Collins, the guy who drew the short straw and had to stay in lunar orbit).

Here is the problem:

It took the Apollo 11 crew four days to reach the moon, blasting off from the Kennedy Space Center on July 16, 1969 and arriving at the moon on July 20. What planet would they be closest to today, about 40 years later, if they'd decided to skip the moon and head out into the solar system?
Extra credit: How many Swedish Fish would it take to form a ring around Saturn that the astronauts could see as they flew by, if they made it that far?

Share the problem with friends, try it out on your blind date tonight, and remember, all you need is your common sense, intuition, and a vague idea of how fast our intrepid crew was traveling.


  1. Assuming some constants...
    If the trip took 4 days and they traveled approx. 384401km (distance from Earth to Moon) then we can approximate that in a single day they traveled approx. 96100.75km.
    The number of days in a 40 year period is 14600, include 10 extra days to account for leap years gives us 14610 days. Multiply the number of days by the distance traveled in a day (14610 x 96100.75) and we get a total distance traveled of 1,403,070,950km.
    Saturn is approx. 1.2Billion KMs from earth so they passed Saturn and are coming up on Uranus at least in another decade and a half! (haha did you guys intend this to be a pun?).

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  3. If only we were so clever! Great analysis, though. I wonder if the numbers look any different if you take into account the very strange path that Apollo 11 took to the moon, though of course we weren't thinking of that here. It's wonderfully convoluted:

  4. Close, but forgetting one thing. Assuming they did not change velocity for the insertion burn, they would have continued at a velocity of ~24,252 mph. Total of 350,640 hours in 40 years, so over 8,500,000,000 miles (~13.7 billion km).

    Even at its farthest you'd be well beyond pluto.