3 ms·
> For every 1018 photons shot at the moon, only a single photon returns to the telescope. Is that really 1018, or did 10^18 get mangled on its way onto the web
by adavies42 15y ago
> For every 1018 photons shot at the moon, only a single photon returns to the telescope.
Is that really 1018, or did 10^18 get mangled on its way onto the web?
- dalke 15y agoThe latter. There's no way that it's reflecting a million watts back to the Earth's surface (1/1018 of the main beam power). Or to put it another way, with a beam "footprint" of 2km across, and with the size of the rover rather less than 100 m across, there's no way it alone could return that high a percentage of the light sent to it.