In the vast field of astronomy, various celestial phenomena and instruments are studied to understand the cosmos. Galaxies, which are massive systems of stars, come in different forms such as elliptical, spiral, and irregular, each with unique characteristics.
Red Shift - Observed shift in light wavelengths occurring when a light source is moving away from an observer.
Black Holes - A star in which matter is condensed and its gravity field is so strong that light cannot escape.
Irregular Galaxy - Galaxy that contains clouds of gas and dust and stars that are in the early stages of their life cycles.
Spectroscopes - An instrument that separates visible light into its various wavelengths.
Radio Telescopes - An instrument consisting of a reflector, a receiver, and an antenna used to collect radio waves from space.
Constellations - Group or pattern of stars.
Light-Year - A measure of the distance light travels in one year, which equals to 9.5 X 10 (to the 12th power) km.
Spiral Galaxy - A disk-shaped galaxy with arms that rotates round a dense center.
Refracting Telescope - An instrument that uses an objective lens to bend light toward the focal plane where the image is formed.
Expanding Universe - Theory that states the universe is currently expanding and shall continue to do so.
Nebula - A low density cloud of gas and dust in which a star is born.
Fusion - The process of two low mass nuclei being joined to form one nucleus; the source of a star's light and thermal energy.
Absolute Magnitude - A measure of a star's actual brightness.
Reflecting Telescope - An instrument in which light is collected, reflected, and focused by a concave mirror and the image formed is magnified in the eyepiece.
Big Bang - A theory stating that the universe originated from the explosion of a huge mass of matter, which cooled, collected into clouds, and formed galaxies.
Main Sequence Star - A star that lies along a diagonal from upper left to lower right on the Hertzsprung-Russell diagram; uses up its hydrogen fuel at a steady rate.
Elliptical Galaxy - A system of stars that contains little dust and gas and may be composed of millions to trillions of stars.
