P8 Space Flashcards
Planets in the solar system
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto (dwarf planet)
Natural satellites
Moons of a planet or dwarf planet
Our moon takes 27.3 days to obit us
A star
Make their own light and have a strong gravitational field
When a protostar gets bigger and hotter from it gravitational field pulling in gas and dust. The core is so hot hydrogen gas fuses which releases energy and ignites the protostar in a massive nuclear reaction. A star is formed
Planet
Spherical
In orbit of a star
Gravitational field strong enough to clear other material outer its orbit
Dwarf planet
Spherical
Orbits a star
Gravitational field strength is too weak to clear other materials out of it orbit
Moon
Orbits planets not stars
Earths orbit
About 150 million km from the sun
Takes a year to orbit the sun
Almost circular orbit
Artificial satellites
Obit the earth for communication, GPS, weather forecasts etc.
They are launched at right angles to the earth so that is stays within the gravitational field
Nebulae
Huge clouds of dust, hydrogen, helium are sometimes the the birthplaces of stars
Protostar
Over millions of years, the force of gravity pulls the gas and dust in the cloud together. As the vast cloud compresses it gets hotter until the core begins to glow.
Nuclear fusion
When hydrogen atoms fuse together to produce large amounts of energy. The hydrogen repels other hydrogen atoms so to over come the high temperatures of 15000000 degrees Celsius must be created by the force of gravity compressing the gases
Main sequence
When stars are at a stable state
Forces in equilibrium
In main sequence stars forces are at equilibrium
Inward force from gravity
Outward force from fusion reactions
Life cycle of stars
10billion year life
The time it takes for all the hydrogen to be bonded into helium
Forces change as helium fuses to create larger (heavier) elements
Although star could potentially collapse and explode if gravity was stronger than outward forces
Red giant
Star has become unstable and outer layers of the star are pushed out to many times the stars original size
Life cycle of a star
Nebula Protostar Sun (main sequence) Red giant White dwarf Black dwarf
Red super giant
3-50x bigger than sun.
Shorter life (millions not billions of years)
Hydrogen used up quicker and star expands & helium nuclei fuse to form larger nuclei of elements such as carbon and nitrogen. With each cycle temperature increases and more lighter nuclei fuse together
Supernova
Fusion stops and the core collapses causing a gigantic explosion which blows the outer layers of the star into space. Distributes elements formed by fusion throughout universe.
Neutron star
If the surviving core is between 1.5&3 solar masses it contracts to become very small and dense
Black hole
If the core is greater than 3 solar masses the core contracts to become a black hole.
The early universe
Only contained clouds of hydrogen with little helium. Clouds of gas were compressed by gravity to form the first stars. Hydrogen started to fuse together and form helium
Making light elements
All elements up to iron are made bumpy nuclear fusion.
The larger the star the greater the range of elements
energy is not released when iron nuclei fuses they require energy to fuse together
Making elements heavier than iron
When the star collapses the temperature becomes high enough for heavier elements such as gold and uranium to be formed. These heavier metals are then spread out and biome part of a new nebula
Red shift
The greater the speed of the light source relative to the observer, the greater the change in wavelength of the light observed
What did Edwin Hubble notice?
Light form distant galaxies had longer wavelengths than expected. Light has wavelengths shifted towards the red end of the spectrum
An expanding universe
Degree if red shift was directly proportional to the distance of the Galaxy away from the earth. The further away a galaxy is from another galaxy, the faster it is moving away from it
Big Bang
Suggests the universe was denser together before and Big Bang was the point in which it started to expand. Also suggests this dense region was extremely hot
Dark matter
The mass of the visible star isn’t enough to hold the stars in orbit around the Galaxy. There must be extra matter that we can not see, which holds galaxies together by gravitational attraction
Dark energy
Most of the mass/ energy of the universe must consist of something we know nothing about for the rate of expansion of the universe to appear to be increasing.
Percentages of energy in the universe
4% visible matter
22% dark matter
74% dark energy
