What I mean is this. Suppose that I am 20km far from the moon. I can see soil details, craters, etc. Then I move to 100km away from the moon. I look at the moon again and now I am unable to see the same level of details as before. Why?
Then comes the real question. We look at distant stars and planets using telescopes. I know that the current telescopes are not about enlarging pictures but gathering photons. But suppose we had at our disposal a telescope with infinite enlargement functionality. Would we be able to choose a planet, distant as hell and enlarge it to the point we could see its surface details or is detail lost forever as the light travels?
If it is lost, how it is lost?
# fantastic answers! THANKS!
In: Physics
Magnification aside, telescopes can see in greater detail because they have an ability that humans do not: they can take photographs with long exposures. The longer they stare at one object, the more light from that object they will be able to accumulate, eventually combining it into a single image formed from data gathered over a large amount of time. People can only ‘see’ things in the moment – they can’t save an image in their head until more light comes in and makes it sharper.
Light spreads out when it travels, and this is true even in a vacuum. Meaning, the further out from the source it travels, the weaker and weaker it gets. Light intensity actually drops off pretty rapidly the further out you get – just think how indescribably bright the sun is up close, and yet only 93 million miles away, and you can stare directly into it and only experience a little bit of discomfort.
Picturing a planet this way is impossible, for a few reasons.
1. It’s parent star would drown it out. Like, entirely.
2. Planets are moving. Constantly. They move in front of [too bright] their star and then behind it [blocked], meaning they wouldn’t stay still for the time needed to gather enough light to make anything out, even if we possible were able to.
3. If *that’s* not bad enough, they also rotate just like the Earth. So the period to capture an image before it’s a blur is down to minutes.
4. The very good point already made about the light coming from the planet/star being drowned out by the rest of the light coming from that direction as the intensity falls too low.
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