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0
votes
1answer
57 views

Why can't the surfaces of stars be observed?

If I'm correctly informed, only three stars: Sol, Betelgeuse and Altair have surfaces which have been resolved by telescopes. All other stars are only point sources of light, even in the greatest of ...
0
votes
1answer
25 views

Adaptive Optics?

I get the general idea of adaptive optics. The light from an object distorted by differences in the earth's atmosphere, and a telescope with AO tries to compensate for this distortion by various ...
3
votes
1answer
52 views

How do telescopes “zoom” and change angle of view?

Images from the Hubble Space Telescope have widely different angles of view. Is this only the result of composing multiple images, or can the telescope itself change its "zooming" optically, ...
0
votes
1answer
48 views

Can the Sun be used as a point source of light to achive better focus?

There's a limit to how well sunlight can be focused by a parabolic reflector or a lens because the Sun is not a point source. I wonder if the sunlight could be engineered to work as if it was (much ...
4
votes
2answers
144 views

Why does e.g. Hubble's secondary mirror not block part of the picture?

The SOHO observatory has an opaque object in the light path that blocks the direct light from the sun making it possible to observe the corona. Hubble and many other telescopes have a big primary ...
3
votes
1answer
157 views

How does a Bahtinov mask work?

For focusing the image of a telescope, one can use a Bahtinov mask. How does this mask work, and how did Mr Bahtinov get the idea to cut such a peculiar shape? Is it possible for me to design my own ...