What is the water hole? Why is so promising to radio astronomers? ...

[DelorasTo]

What is the water hole? Why is so promising to radio astronomers?
 
  What will be an ideal response?

Question 2

Why are type O, A, and M stars considered poor candidates to find a technological civilization?
 
  What will be an ideal response?

[ryrychapman11]

Answer to Question 1

The water hole is the region of the radio spectrum between 18 cm (natural wavelength of the hydroxyl, OH, molecule and 21 cm (natural wavelength of atomic hydrogen, H). Hydroxyl and hydrogen combine to form water, and the 18- to 21-cm region of the spectrum is relatively free of background noise. Thus it is believed that the so-called water hole is a natural band for communication between galactic civilizations.

Answer to Question 2

Considering the time it took life on Earth to arise, type O and A stars have too short a lifetime to give life a chance to evolve into higher forms. Type M stars are so cool that they have a very small habitable zone, thus reducing the likelihood a planet would be in the right position.

[DelorasTo]

Thanks for the timely response, appreciate it

[shewald78]

Excellent