The brightest type of active galactic nucleus, believed to be powered by a supermassive black hole. The word “quasar” is derived from quasi-stellar radio source, because this type of object was first identified as a kind of radio source. Quasars also are called quasi-stellar objects (QSOs). Thousands of quasars have been observed, all at extreme distances from our galaxy.
An object that orbits Earth, the moon, or another celestial object. Artificial satellites are man-made objects placed into orbit. Natural satellites are smaller celestial bodies that orbit around larger celestial bodies. Two examples are moons that go around planets and small galaxies that orbit larger galaxies.
The sixth planet in the solar system, noted for its obvious ring structure. Saturn is almost ten times the Earth's distance from the Sun. The planet completes a circuit around the Sun in about 30 Earth years. Saturn is the second largest and the least dense planet in our solar system. The planet has more than 21 moons, including Titan, the second largest known moon in our solar system.
The Sun and its surrounding matter, including asteroids, comets, planets, and moons, held together by the Sun's gravitational influence.
The study and interpretation of a celestial object’s electromagnetic spectrum. A spectrum breaks light into its component wavelengths and reveals clues to the object’s state, temperature, speed, quantity, distance, and composition.
A spiral-shaped system of stars, dust, and gas clouds. A typical spiral galaxy has a spherical central bulge of older stars surrounded by a flattened galactic disk that contains a spiral pattern of young, hot stars, as well as interstellar matter.
A huge ball of gas held together by gravity. The central core of a star is extremely hot and produces energy. Some of this energy is released as visible light, which makes the star glow. Stars come in different sizes, colors, and temperatures. Our Sun, the center of our solar system, is a yellow star of average temperature and size.
A galaxy undergoing an extremely high rate of star formation. Starburst galaxies contain massive, deeply embedded stars that are among the youngest stars observed.
A group of stars born at almost the same time and place, capable of remaining together for billions of years because of their mutual gravitational attraction.
The explosive death of a massive star whose energy output causes its expanding gases to glow brightly for weeks or months. A supernova remnant is the glowing, expanding, gaseous remains of a supernova explosion.
The glowing, expanding, gaseous remains of a supernova explosion.