3 ms·

I wonder how long much longer it will take for the astronomers to get the technology that would allow them to hunt for life in other stellar systems so that we

• Balgair 9y ago
  Depends on the size of the dish, really. You need to resolve the 'signs of life' at stellar distances. Street-Math time!: Lets assume that means you need to resolve a meter sized elephant on another planet. Lets choose Vega, as that is ~25ly away, really the furthest star we can go to (and return from) and still have someone alive here to have a beer with afterwards (50 year round trip). 25ly is about 2.3E19 meters away. A 1 meter sized elephant at 2.3E19 meters is about 4.3E-20 radians. Lets use wavelengths in the visible spectrum. Hydrogen's Balmer peak at 656nm is a nice red color to look at (though stellar issues abound here). The resolution of a telescope is approximately : R = L/D. R is resolution, L is the wavelength, D is the diameter. Rearranging we get the diameter to be : D = L/R. Plugging in a L of 656nm (~6.6E-7m) and a R of 4.3E-20radians and you get D. D is about 1.5E13 meters. For reference the earth is about 1.2E7 meters, about 6 orders of magnitude smaller. 1.5E13 meters is about 14 light-hours, much larger than the Earth-Sun distance. Soooooo, I think it's going to be a while ... ;)