angular sizes of point sources - quiz
The Angular Sizes of Stars
These are optical image of several stars, including the central star of HT Cas, from the Schmidt telescope. Each pixel in each image is 0.0005 degrees across. The stars themselves are different sizes. You may think that a telescope gives a perfectly magnified image of a far away object. In fact, telescopes are not perfect, and the images from a telescope suffer from various distortions. The distortions tend to spread out the light from a source. This is especially important in the case of stars, which are so far away that they are actually "point sources", with the light of the star coming from one point in space.
|Click here if you cannot determine HT Cas' angular size from this image|