Critical+Vocabulary


 * Hertzsprung-Russel Diagram:** A graph of the absolute magnitude of stars plotted against their surface temperature or color, used in the study of stellar evolution.

**Magnitude** The great size or extent of something.

**Luminosty:** The intrinsic brightness of a celestial object (as distinct from its apparent brightness diminished by distance).

**Nebula:** A cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against...

**Main sequence:** The main sequence is a continuous and distinctive band of stars that appear on plots of stellar color versus brightness.

**Giant:** a very bright star of large diameter and low density (relative to the Sun).

**Super Giant:** These are the largest, brightest stars known. Of luminosity classes I, they are found along the top of the HR diagram and have evolved.

**Supernova:** A supernova (plural supernovae) is a stellar explosion that is more energetic than a nova.

**Dwarfs:** A star of relatively small size and low luminosity, including the majority of main sequence stars

Galaxy: A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

Fusion: The process or result of joining two or more things together to form a single entity. Black Hole: A region of space having a gravitational field so intense that no matter or radiation can escape. Neutron Star: A celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed. Protostar: A contracting mass of gas that represents an early stage in the formation of a star, before nucleosynthesis has begun.

Scientific Theory: a theory that explains scientific observation

Big Bang Theory: A cosmological theory holding that the universe originated approximately 20 billion years ago from the violent explosion of a very small agglomeration of matter of extremely high density and temperature.

- Light Years: A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles)

-Light Second: the distance light travels in a vacuum in one second; approximately 300,000 kilometers.

-Apparent Magnitude: The magnitude of a celestial object as it is actually measured from the earth. -Absolute Magnitude: The magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.