Astronomy & Astrophysics: Astronomy Overview

Planetoid, or minor planet, small body orbiting the sun. More than 10,000 asteroids have orbits sufficiently well known to have been cataloged and named; thousands more exist.

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.

A small celestial body consisting mostly of dust and gases that moves in an elongated elliptical or nearly parabolic orbit around the sun.

One of the 88 areas into which the sky is divided for the purposes of identifying and naming celestial objects.

Grouping of millions or billions of stars, held together by gravity.

From Collins Dictionary of Astronomy
A catalog of the brightest ‘nebulae’ prepared by the French astronomer Charles Messier and printed in final form in 1784.

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.

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.

The sun and the surrounding planets, natural satellites , dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity.

Luminous globe of gas, mainly hydrogen and helium, which produces its own heat and light by nuclear reactions.

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.

Totality of matter and energy in existence.

In astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation).

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.

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.

Area of science that aims at a comprehensive theory of the structure and evolution of the entire physical universe.

Or astrobiology, search for extraterrestrial life within the solar system and throughout the universe.

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.

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.