Language/English/Vocabulary/Astronomy

In today's lesson, we are going to learn some vocabulary related to astronomy. Please edit this wiki page to complete it 😊

The Earth

The planet you are on now. See Planet.

Space

Everything that exists outside of The Earth and its atmosphere. Note that we do not use the definite article with "Space".

The Universe

Everything that exists in space plus the Earth.

Galaxy

A system of millions of stars held together by gravity.

Star

A star is a type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The sun is the star closest to our planet.

The Sun

The star which is closest to our planet and which we can easily observe in the sky, especially during daytime.

Solar System

Any collection of planets and their moons orbiting around a star; "Our Solar System" consists of eight planets (the Earth included), some of them with one or more moons, asteroids and our sun.

Solar Wind

The high energy particles emitted from the Sun as a result of heating and nuclear fusion. These have enough energy to escape the Sun's gravity.

Asteriod

A celestial body smaller than a planet moving in an elliptical orbit around a star. Another term used for an asteriod is a planetoid.

Meteor

An asteroid which is pulled towards a planet or moon and then heats up in its atmosphere.

Meteorite

A meteor or a piece of one which has landed on the Earth, another planet or moon which has not completely been evapourated during its passage through an atmosphere after heating up.

Orbit

The path of a celestial object which it takes around another celestial body. For example, the orbit of the Earth around the Sun takes exactly 1 year.

Comet

A type of meteorite which consists of ice, dust and rocky matter and possibly carbon compounds with a highly elliptic orbit. When it comes close to the sun, it heats up because of solar wind and then emits a tail of gas and dust which points away from the sun. These can sometimes be seen from the Earth.

Planet

A heavy celestial body moving in an elliptical orbit around a star. The more technical details are that it has enough mass to assume a nearly spherical shape as a result of achieving hydrostatic equalibrium, it has cleared its neighbouring orbital region of other bodies.

Dwarf Planet

A celestial body which is "almost a planet". The most famous example is Pluto, which is no longer classified as a planet. Technically speaking, it fulfills just about all the definitions of a planet, but might miss or nearly miss one or two. In the case of Pluto, it has been unable to substantially clear all the asteriods and other celestial bodies which it comes across in the neighbourhood of its orbit around the Sun.

Black Hole

A celestial body from which nothing can escape from its gravitation pull, not even light. These often occur at the centre of galaxies.

Moon

A natural satellite orbiting a planet. "The Moon" refers to the Earth's own natural satellite.

Saturn, Uranus, Mars, Venus, Mercury, Jupiter, Neptune

These are planets in the solar system.