- Asteroid: Topic Page
Any of thousands of small rocky objects, 1km to 1000km in diameter, that orbit around the Sun, mainly between the orbits of Mars and Jupiter.
- Brown dwarf: Topic Page
A star with very low mass (less than 8% of that of the Sun) such that thermonuclear reactions cannot occur, its dim appearance being the result of contraction due to gravitational force and constant release of energy.
- Comet: Topic Page
A small celestial body consisting mostly of dust and gases that moves in an elongated elliptical or nearly parabolic orbit around the sun.
- Constellation: Topic Page
One of the 88 areas into which the sky is divided for the purposes of identifying and naming celestial objects.
- Galaxy: Topic Page
Grouping of millions or billions of stars, held together by gravity.
- Messier Catalog
From McGraw-Hill Concise Encyclopedia of Science and Technology
An early listing of nebulae and star clusters. Although Charles Messier (1730–1817) was primarily a comet hunter, he is remembered for his catalog of objects.
- Nova: Topic Page
Faint star that suddenly erupts in brightness by 10,000 times or more, remains bright for a few days, and then fades away and is not seen again for very many years, if at all.
- Orbit: Topic Page
In astronomy, path in space described by a body revolving about a second body where the motion of the orbiting bodies is dominated by their mutual gravitational attraction.
- Planet: Topic Page
A celestial body, in orbit around the Sun or another star, which has too small a mass to become a star itself, and shines by reflecting light from the star around which it revolves.
- Solar system: Topic Page
The sun and the surrounding planets, natural satellites , dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity.
- Star: Topic Page
Luminous globe of gas, mainly hydrogen and helium, which produces its own heat and light by nuclear reactions.
- Supernova: Topic Page
A massive star in the latter stages of stellar evolution that suddenly contracts and then explodes, increasing its energy output as much as a billionfold.
- Universe: Topic Page
Totality of matter and energy in existence.
- White dwarf: Topic Page
In astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation).
- Astrology: Topic Page
Study of the relative position of the planets and stars in the belief that they influence events on Earth.
From Astronomy Encyclopedia
Branch of astronomy that uses the laws of physics to understand astronomical objects and the processes occurring within them. The terms ‘astronomy’ and ‘astrophysics’ are however often used as synonyms.
- Biology: Topic Page
Science of life. Biology includes all the life sciences - for example, anatomy and physiology (the study of the structure of living things), cytology (the study of cells), zoology (the study of animals), botany (the study of plants), ecology (the study of habitats and the interaction of living species), animal behaviour, embryology, and taxonomy (classification), and plant breeding.
- Cosmology: Topic Page
Area of science that aims at a comprehensive theory of the structure and evolution of the entire physical universe.
- Exobiology: Topic Page
Or astrobiology, search for extraterrestrial life within the solar system and throughout the universe.
- Physics: Topic Page
Branch of science traditionally defined as the study of matter, energy, and the relation between them; it was called natural philosophy until the late 19th cent. and is still known by this name at a few universities.
- Space Exploration: Topic Page
The investigation of physical conditions in space and on stars, planets, and other celestial bodies through the use of artificial satellites, space probes, and spacecraft with human crews.
- Space Science: Topic Page
Body of scientific knowledge as it relates to space exploration; it is sometimes also called astronautics.