Hobbies And Interests
Stars
According to NASA, a star is "a huge, shining ball in space that produces a tremendous amount of light and other forms of energy." Except for Earth's sun, stars look like twinkling points of light. The sun looks bigger to us because it's closer.
Types of Stars
There are many kinds of stars, including white and black dwarfs, neutron stars and supergiants. White dwarf stars occur after a planetary nebula fades. This kind of star consists mostly of carbon and oxygen.
Other Types of Stars
A black dwarf star is basically a dying star; it's the end of the life cycle of an intermediate-mass star. Neutron stars are made almost entirely of neutrons, but they are so small their light is hard to see. A supergiant is a massive star--the largest star known--about the diameter of the solar system out to the planet Jupiter.
Galaxies
NASA defines a galaxy as "a system of stars, dust, and gas held together by gravity." The eight planets in our solar system---nine if you still count Pluto--are in a galaxy called the Milky Way. Scientists estimate that there are more than 100 billion galaxies scattered throughout the visible universe.
Types of Galaxies
There are several different types of galaxies, including spiral galaxies, lenticular galaxies, elliptical galaxies and irregular galaxies. Spiral galaxies usually consist of two major components: a flat, large disk and young star clusters. Lenticular galaxies are essentially short, spiral galaxies.
Other Types of Galaxies
Elliptical galaxies are ellipsoidal in shape, usually triaxial and sometimes referred to by scientists as cosmic footballs. Irregular galaxies are oddly shaped and don't really fit in with other galaxies because their gravitation is distorted.