PT7.S1.Q16 - comets do not give off their own light

Seriousbird

This question really baffles me. How can B be correct? If the probe reveals that the light reflected is much less, how would that support B? Please help, I'm so confused!

runiggyrun

So, let's say for the sake of the argument that they believed that each lb of mass reflects 60 units of light. They measured 600 units, so they thought OK, so it must weigh 10 lb. Now they discovered that the material reflects 60 times less light - each lb of mass only reflects 1 unit of light. But they still measured 600 units - that hasn't changed. Therefore it must now mean that the planet weighs 600 lb. B is correct, the previous estimates were too low.
Less bang for the buck than previously thought - to get the same amount of bang you need more bucks

Seriousbird

Thank you. I have to admit, at first I didn't get it, but then I took a break and looked at your reasoning and it makes sense. Thank you!