Quote:
Originally Posted by polak
No physics expert either so I might be wrong, but I'm not talking about the speed of the light. Light dispurses as it travels away from the source. Only a small fraction of the light from the sun hits this planet (which is further than pluto, at least in the time we've been looking with telescopes) and then even less of that light hits earth on it's way back.
Galaxies and stars emit way more light than this relatively microscopic (compared to stars and galaxies) planet reflects.
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You're right on the point that a planet is much dimmer than a galaxy You also have to consider the planet's albedo (reflectivity of sunlight).
Also remember that you have to know where to look to observe objects. Distant planets like Neptune (and formally Pluto) are two far away to observe on one's own. They were both discovered in the same manner as this possible planet - by observe the motions of objects near them and inferring that a planet was affecting them.
Once you run the calculations you can then aim a telescope to that area of the sky.