“With a ninty-four-inch telescope in space, we’ll be able to see phenomenal detail on planets,” I remarked.
“Just think what you could do if you pointed it at the earth,” Greg said.
“Why bother? All the interesting things are in the sky. And anyway, the Space Telescope physically can’t point to the earth. Its sensors will burn out if you try.”
“What if someone made such a telescope and pointed it to the earth. What could you see?”
I fiddled a few numbers in my head. Say, three hundred miles up in orbit, a nintyfour-inch telescope. The wavelength of light is about four hundred nanometers.… “Oh, you could easily see detail of a couple feet across. The limit would be around a couple inches. Not quite good enough to recognize a face.”
Greg smiled and said nothing. It took a while, but it eventually sunk in: the astronomical Space Telescope wasn’t the only big telescope in orbit. Greg was probably talking about some spy satellite. The secret KH-11, most likely.
“With a ninty-four-inch telescope in space, we’ll be able to see phenomenal detail on planets,” I remarked.
“Just think what you could do if you pointed it at the earth,” Greg said.
“Why bother? All the interesting things are in the sky. And anyway, the Space Telescope physically can’t point to the earth. Its sensors will burn out if you try.”
“What if someone made such a telescope and pointed it to the earth. What could you see?”
I fiddled a few numbers in my head. Say, three hundred miles up in orbit, a nintyfour-inch telescope. The wavelength of light is about four hundred nanometers.… “Oh, you could easily see detail of a couple feet across. The limit would be around a couple inches. Not quite good enough to recognize a face.”
Greg smiled and said nothing. It took a while, but it eventually sunk in: the astronomical Space Telescope wasn’t the only big telescope in orbit. Greg was probably talking about some spy satellite. The secret KH-11, most likely.