Unit C - The Study Of The Universe Flashcards
Galaxy
A collection of hundreds of billions of stars held together by gravity
Universe
The term used to refer to everything that physically exists: the entirety of space and time, and all forms of energy
Celestial objects
Objects we can see in the sky e.g. the Sun, the Moon, Earth
Astronomy
The study of the universe and and the objects in it
The Solar system
Made up of the Sun, the 4 rocky inner planets, the 4 gas giant planets and other objects held my hw suns gravity such as asteroids, comets and moons
Star
A hot ball of plasma, an electrically charged gas, that shines because nuclear fusion is taking place at its core
Nuclear fusion
The process in which the nuclei of atoms fuse together and form larger atoms
Astronomical Unit (AU)
The average distance between the Suns and the Earth, about 150 million km
Light Year (ly)
The distance a beam of light can travel through space in 1 year, 63 000 AU or 9000 billion km
Asteroid Belt
A region of rocky debris that forms a ring all the way around the Sun at a distance of about 3 AU
Binary System
A system with two stars, more than half of the star systems have two or more stars
Supernova
The explosion of a star where the outer layers of the star are pulled into the core by gravity. As the outer material crashed into the inner core, the temperature and pressure increase until the star explodes
Nebula
A large cloud of dust and gas. Also called a star nursery, because stars develop from the dust and gas.
The Milky Way
The galaxy inside which is our solar system. It’s a spiral galaxy and 100 000 ly across and about 2000 ly think at its widest point near the core.
Black hole
A region of space where gravity is so strong that nothing, not even light can escape.
Dark Matter
Matter in the universe that is invisible because it doesn’t interact with light or any other kind of radiation.
Galaxy Shapes
Spiral, Barred Spiral, Elliptical, Irregular
Visible light spectrum
The rainbow band of colours into which white light separates when it passes through a prism.
Big Bang Theory
The universe formed when an infinitely dense point suddenly and rapidly expanded in a single moment.
George Gamow and Ralph Alpher
When did the universe form?
13.7 billion years ago
Electromagnetic radiation
A form of energy emitted and exhibited by charged particles that travels in waves.
The electromagnetic spectrum from long to short waves
Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma ray
Spectroscope
An optical instrument that separates light into spectral colours.
Spectral lines
A series of dark lines that appear across a stars band of colour, as each gas that makes up a star absorbs some of the light energy.
Spectral shifting
The change in position of spectral lines to the left or the right of where they normally are in the spectrum of a light source that is not moving.
Cosmic Background Radiation
Microwave energy left over from the massive and split- second expansion of the universe from a single point some 13.7 billion years ago.
Constellation
A group of stars that, from Earth, resemble a recognizable form.
Asterisms
Smaller recognizable star patterns within a larger constellation.
Astronomical phenomenon
Any observable occurrence relating to astronomy.
Formation of a star
Inside a collapsing nebula triggered by a disturbance such as the gravitational attraction of a nearby star or a shockwave from an exploding star.
Protostar
A star in its first stage of formation.
Hertzsprung - Russell Diagram
Plotted data of stars and are arranged by
- colour
- luminosity
- surface temperature
Comet
A celestial object made of ice and dust.
Meteoroids
Small pieces of rock and metal that travel throughout the solar system with no fixed path.
Meteor
A meteoroid that begins to burn up as a result of friction upon entering the Earths atmosphere.
Rotation
Earths rotation takes almost 24 h with it moving at 1670 km/h and tiled at an angle of 23.5 degrees.
Solar eclipse
Occurs when the moon blocks the suns light to viewers on earth. The moon lie directly between the earth and the sun making it seem as though the sun has disappeared.
Lunar eclipse
Occurs when the earth blocks out the suns light shining on the moon making the moon disappear fully or partially for a moment.
Equinox
A day when the hours of daylight and the hours of night are of equal length.
Orbital radius
A planets distance from the Sun.
4 types of spacecraft in use
-Rockets
Lift small capsules containing crew, equipment or satellites
-Space shuttles
Transport personnel and equipment to orbiting spacecraft
-Space stations
Orbiting spacecraft that have living quarters, work areas, and everything needed to allow people to live and work in space for extended periods
-Space probes
Carry instruments for robotic exploration of space
International space station
Assembled in stages since 1998 and orbits 400 km above Earth. Has the Canadaarm2
Artificial satellite
A device placed in orbit around Earth or another celestial object.
Geostationary orbit
When a satellite orbits the Earth at the same rate as the Earth rotates.
