Gas heated to a state where it contains ions and free-floating electrons. Also referred to as plasma.

A system consisting of a spiral galaxy surrounded by several dwarf white galaxies, often ellipticals. Our galaxy and the Andromeda galaxy are examples of hypergalaxies.

Absolute magnitude – also known as absolute visual magnitude, relates to measuring a heavenly object’s brightness when viewed from 10 parsec or 32+ light years.

The international community agreed to define absolute zero as equivalent to −273.15°C on the Celsius scale or−459.67°F on the Fahrenheit scale. It is the theoretical temperature entropy reaches its mi [..]

are a dark feature in the spectrum of a star formed by cooler gases in a star’s outer layer.

arise when material, usually gases, are transferred from one celestial object to another. There are two places astronomers find accretion disks, binary star systems and galactic nuclei.

is a combination of lenses made of different glass. These bring two wavelengths into focus (normally red & blue) on the same plane. Achromatic lenses are used to take chromatic aberrations away fr [..]

is a region in the center of a galaxy that has a higher than normal brightness. It is a class of galaxies that emit a large amount of energy from their center more than ordinary galaxies.

Technology developed in the 80’s for reflecting telescopes. The construction enables telescopes to move 8 meter primary mirrors. As the name suggests, it works by “actively” adjusting the telescope mi [..]

technology used to improve performance of optical systems through the reduction of rapidly changing optical distortion. It is used to remove atmospheric distortion through the use of astronomical tele [..]