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Astronomy 1021
Ch. 1
Term | Definition |
---|---|
Field of view | The area visible in an image. Usually given as the diameter of the region. |
Scientific notation | The system of recording very large or very small numbers by using power of 10. |
Astronomical Unit | Average distance from Earth to the Sun; 1.5 x 10^8 kilometres. |
Solar system | The sun and its planets, asteroids, comets, and so on. |
Planet | A non-luminous body in orbit around a star, large enough to be spherical and to have cleared its orbital zone of other objects. |
Star | A globe of gas held together by its own gravity and supported by the internal pressure of its hot gases, which generate energy by nuclear fusion. |
Light-Year (ly) | Unit of distance equal to the distance light travels in one year. |
Galaxy | A large system of stars, star clusters, gas, dust, and nebulae orbiting a common centre of mass. |
Milky Way | The hazy band of light that circles our sky, produced by the glow of our galaxy. |
Milky Way Galaxy | The spiral galaxy containing our Sun, visible in the night sky as the Milky Way. |
Spiral arms | Long spiral pattern of bright stars, star clusters, gas and dust. Spiral arms extend from the centre to the edge of the disk of spiral galaxies. |
Superclusters | A cluster of galaxy clusters. |