Earth and Space Flashcards
Astronomy
The study of the universe and everything in it
Geocentric
A theory of the structure of the solar system in which the earth was thought to be at the centre
Heliocentric
A theory of the structure of the solar system where the Sun is at the centre.
Universe
Everything that exists, including planets, stars, galaxies and all forms of matter and energy.
Big Bang
Most scientists believe that the universe began with an explosion - the Big Bang - about 14 billion years ago.
Galaxy
A large group of stars, dust, gas and dark matter held together by gravity.
Antimatter
The mirror image of matter. Every particle of matter has a corresponding particle of antimatter. When they meet they destroy each other and are converted into pure energy.
Hypothesis
Collection of ideas that seem to explain what is observed
>predictions that can be tested
Models
Describes reality based on Hypothesis that have withstood observational and experimental tests >explains with mathematics properties and behaviors of some object or phenomenon
Theory
Series of well-tested hypothesis that together from a self-consistent and accurate description of nature >capable of making predictions that can be tested and verified by anyone
Laws
Proven theories that have stood the test of time and have broad applicability
Constellation
Some of these stars seem to be grouped forming images in the sky
There are 88 constellation covering the entire sky
Ecliptic plane
Plane of Earth’s orbit around the sun
The orbit is not quite a circle (eclipse) squashed circle
Antimatter
matter consisting of elementary particles which are the antiparticles of those making up normal matter.
Solar system
Our solar system includes the Sun and all the objects that orbit around it due to its gravity, including the Earth.
Celestial body
Any natural body outside of the Earth’s atmosphere. There are various celestial bodies, including planets, stars, moons, comets and asteroids.
Planet
An object that is in orbit around a star, has sufficient mass to assume a nearly round shape, and has become gravitationally dominant. This means that it can clear the space debris in its orbit
Moon
A natural satellite that orbits a planet
Star
A ball of heat radiating gas that is held together by gravity. Stars contain mostly hydrogen as well as helium and smaller amounts of other elements.
Sun
The star that lights and heats our planet. The Sun is powered by a fusion reaction at its core.
Light-year
The distance that light travels in one year. Light-years are often used in astronomy to describe the distance to faraway stars and galaxies.
Asteroid
Lumps of rock that orbit the Sun but are too small to be classified as planets. There are three types of asteroids, divided based on what they are made up of:
C-type asteroids are made up of carbon compounds;
S-type asteroids are made up of stony material;
M-type asteroids are mostly made of metals, such as iron.
Comet
A celestial body that orbits the Sun, made up of a nucleus, a coma and one or more tails. The nucleus of a comet is made up of dust and ice. The coma (a fuzzy outline or atmosphere caused by the Sun’s radiation) is made up of carbon dioxide, dust and water vapour. The tail is made up of gas and dust produced by the nucleus.
Terrestrial planet
Planets made up of rock. In our solar system, the terrestrial planets are the four inner planets.
Gas giant
The outer planets in our solar system are called gas giants because they are mainly made of gases hydrogen and helium.
Gravity
A non-contact force of attraction between objects. There is a gravitational pull between all masses.
Force field
A region in space where an object feels a force.
