The reason other stars look so small is because they are so far away. The sun is an average star compared with other stars in the universe and is one of some 200 billion within the Milky Way galaxy. The Sun appears to be brighter and larger than any other stars simply because of the close distance to Earth. The temperature of the star also determines the brightness, which can be determined from the color of the star. The mass of a star can be determined if it is gravitationally attached to a partner, or binary star.
Binary stars are a pair of stars that orbit each other attaching themselves by a common point.
This point is called the center of mass. If one star is more massive than the partner star then the center of mass is closer to the bigger star and the stars will become two units. An example of a binary star is in the constellation Big Dipper. Images These Hubble telescope images and more can be found at Jim DeLine's site .They are the copyright property of Jim DeLine and The Association of Universities for Research in Astronomy . The image on the left is Comet Hyakutake when it passed Earth 9.3 million miles away.