I recently saw a photo somebody posted of a galaxy 50 million light years away. I have always wondered, why doesn’t he point it at the moon or even a planet 10 light years away and see the surface up close? We might see water or certain organisms. I have yet to see a picture like that in my lifetime. Thanks in advance for the answer.
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> see the surface up close. We might see water [droplets] or certain [microscopic] organisms.
A telescope is not a microscope. The microscope works by taking a very bright point of light and **magnifying** it. The telescope works by taking vast amounts of spread out light (diffuse light) and **focusing** it. Telescopes are not binoculars or magnifying glasses either. Binoculars work by taking a small amount of straight focused light (not diffuse) and magnifying it.
If you point the telescope to a nearby object, say the moon, it will take in vast amounts of light of equal luminosity and focus it all down to a uniform pixel. You won’t see any fine detail, certainly not any organisms or water droplets.
Here’s a relevant passage from an article on the Hubble telescope about its optical limitations.
>Hubble’s 94.5-inch mirror has a resolution of 0.024″ in ultraviolet light, which translates to 141 feet (43 meters) at the Moon’s distance. In visible light, it’s 0.05″, or closer to 300 feet. Given that the largest piece of equipment left on the Moon after each mission was the 17.9-foot-high by 14-foot-wide Lunar Module, you can see the problem.
We can’t see solar systems that far away. For the most part, we can’t even see individual stars. We can see galaxies because they are very large, very bright, and stand still nicely for ultra-long exposures.
The same degree of magnification that displays distant galaxies shows things on the scale of mountains on other planets and the scale of parking lots on the moon.
Same reason you can see a camp fire many miles away at night but can’t see the detail of an ant’s foot a few feet away from you even in daylight.
is about what can be resolved with the imaging technology
>**Hubble’s** 94.5-inch mirror has a resolution of 0.024″ in ultraviolet light, which translates to 141 feet (43 meters) at the **Moon’s** distance. In visible light, it’s 0.05″, or closer to 300 feet.
so objects smaller than 300′ across are simply too small to be resolved, they would be smaller than a single pixel in an image generated by the hubble
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