8 Space Flashcards
What is a light-year?
A unit of distance for astronomical scales. The distance light can travel in one earth year.
How many stars are in our solar system?
One - the sun
Name the planets in our Solar System in order of distance from the sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What is a planet?
A non-luminous, spherical object that orbits a star. It must dominate its orbit.
What is a moon?
A non-luminous, natural object that orbits a planet.
What is a galaxy?
A large collection of dust, gas and stars (each a possible planetary system of its own) held together by gravity.
What type of object is Pluto?
Dwarf planet
What is a ‘dwarf planet’?
A planet-like object in space that orbits a star but doesn’t match all the rules of being a planet
What is the name of our galaxy?
Milky Way
What is found in the spaces between astronomical objects (such as planets, moons, asteroids)?
There is a small amount of dust but there?s no air (we think of it as a vacuum), so sound can?t travel, but there is still gravity due to all of the masses nearby.
How was the Sun formed?
From clouds of dust and gas drawn together by gravity, which caused fusion reactions to occur.
What is a nebula?
A cloud of dust and gas in space
What is a protostar?
The earliest stage in the life cycle of a star. Formed when the force of gravity causes a nebula to collapse. The increased temperature and pressure allows fusion to begin.
What is a main sequence star?
A star during the main part of its lifecycle. The radiation pressure outwards from nuclear fusion balances the force of gravity inwards.
What is a red giant?
A star, about the same size as our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium
What is a red supergiant?
A star, much larger than our sun, that has expanded and cooled. It has used up all the hydrogen in its core and is now fusing helium
What is a white dwarf?
The hot, dense solid core of a red giant once it has ejected its outer layer as a planetary nebula.
What is a black dwarf?
A white dwarf that has cooled sufficiently that it no longer emits significant heat or light.
What is a supernova?
An explosion produced when the core of a red supergiant collapses. Elements heavier than iron are formed and ejected into space.
What is a neutron star?
The core of a red supergiant that has collapsed but can still be seen
What is a black hole ?
The core of a red supergiant that has collapsed. These are formed if the remaining core has a mass of more than 3 times the mass of the Sun. It is so dense that light can not escape it.
When the temperature within a protostar gets high enough, what process can begin?
Nuclear fusion (of Hydrogen into Helium)
What force brings the dust and gas inside a nebula together to form a star?
Gravitational force
Describe what happens to stars the size of the sun or smaller after the main cycle
Hydrogen runs out, Hydrogen fusion stops, Helium nuclei fuse to form larger nuclei (up to iron), star expands to be become red giant, eventually outer layers drift away leaving a white dwarf, then black dwarf