Question

Suppose that in the not so distant future an astronaut on the Moon turns on a 100 W light bulb during a lunar eclipse (i.e. the Moon becomes dark as seen from Earth). You can assume that all of the emitted power is in the visible. The light is emitted uniformly in all directions. a) Calculate the number of photons per second emitted by the light bulb. b) In the dark, when your pupils are dilated, they have a diameter of about 7 mm. Calculate the number of photons per second that enter one of your eyes from the light bulb. c) Calculate the number of photons per second from the lightbulb that can be captured by one of the Gemini telescopes. d) Do you think that you will be able to see the light bulb? Do you think that the Gemini telescope will be able to detect the light bulb? Note: The Earth-Moon distance is 3.8×10^5 km. The diameter of the Gemini telescope is 8.1m.

Answer 1