Answer:

Seti searches (or “search for extra terrestrial intelligence”) is a collective term for different scientific searches for intelligent extraterrestrial live. Some examples of these searches are the monitoring of some electromagnetic waves in order to find a type of comunication.

The range of wavelengts is the range in wich the comunications may took place.

One good range is, in the microwaves, the range from 1 GHz to 10 GHz.

Other interesting range is the range of the “water hole”, that goes from 1420 MHz to 1720 MHz, this range is interesting because the molecules of water emit at 1420MHz, and the hidroxyl molecules emane ini a range from 1600MHz to 1720MHz

Here the ranges are given en frequencies, but we can obtain the wavelengths by the equation:

velocity = wavelenght/freq.

where the velocity is c = 3*10^8m/s

for the more general range we have:

λ1 =  3*10^8m/s*(1*10^9 Hz) = 3*10^17 m

λ2 = 3*10^8m/s*(10*10^9 Hz) = 3*10^18 m

and the range for the “water hole” is:

λ1 =  3*10^8m/s*(1420*10^6 Hz) = 4.260*10^17 m

λ2 = 3*10^8m/s*(1720*10^9 Hz) = 5.160*10^17 m