Stars
A distinctive pattern in the night sky formed by a group of stars; the pattern often looks like a familiar object, such as an animal
Constellation
The regular path of an object, such as a celestial body or an artificial satellite, around another body such as a star or a planet
Orbit
An apparent switch in the motion of a celestial body from eastward to westward motion, or vice versa, as viewed from Earth
Retrograde Motion
The thin outer layer of the Sun where hot gas rises to the surface, cools, and then sinks back into deeper layers; reaches temperatures of about 5800°C
Photosphere
A natural object in space, such as the Sun, the Moon, a planet, or a star
Celestial Body
The fusion of two or more atoms to create a different, larger atom, and a great deal of energy
Thermonuclear Reaction
A celestial body that orbits one or more stars, is large enough that its own gravity holds it in a spherical shape, and is the only body occupying the orbital path
Planet
Representing the Sun as the centre of the universe
Heliocentric
The outermost part of the Sun’s atmosphere, a layer of gas that can reach more than 3 000 000°C
Corona
An ancient instrument used to locate and predict the positions of the Sun, Moon, planets, and stars
Astrolabe
A star pattern that is not a constellation; may consist of a small group of stars within a constellation or individual stars from different constellations
Asterism
One of many small rocky bodies in our solar system, most of which orbit the Sun between Mars and Jupiter
Asteroid
A measurement equal to the average distance between the Sun and Earth, about 150 million km
Astronomical Unit (AU)
Dark patches on the Sun’s surface that are slightly cooler, about 3500°C, than surrounding areas
Sunspots
The path followed by the Sun through the sky, as seen from the Earth
Ecliptic
A constellation that never appears to “set”, or dip below the horizon; this classification depends on the position of the viewer
Circumpolar Constellation
Streams of high-energy particles ejected by the Sun; when some of these particles enter Earth’s atmosphere they cause the auroras, or the northern and southern lights
Solar Wind
The passage of a planet between the Earth and the Sun
Transit
Large loops of super-hot gas that extend out from the Sun’s surface
Solar Prominences
A celestial body that orbits a planet
Moon
A celestial body of hot gases with a nuclear furnace at its core that makes its own thermal energy
Star
A small body made up of rocky material and ice that occurs in the Kuiper Belt and the Oort Cloud; when one of these is bumped into the inner solar system, the Sun’s light may make the "tail" visible from Earth
Comet
Representing Earth as the centre of the universe
Geocentric
The 3000 km thick layer of atmosphere beneath the Sun’s corona, composed of hot (6000–20 000°C), low-density gas
Chromosphere
An instrument that gathers and focusses light or other types of electromagnetic radiation to magnify distant objects
Telescope