Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
69 Cards in this Set
- Front
- Back
|
Milky way |
Galaxy containing billions of stars |
|
|
Galaxy |
Cluster if billions of stars held together by gravity |
|
|
Sun’s gravitational field |
Keeps many objects in orbit around it |
|
|
Solar system order |
Mercury, venus, earth, mars, jupiter, saturn, uranus, neptune |
|
|
Moons |
Natural satellites which orbit a planet |
|
|
Dwarf planets |
Gravitational field strength not enough to clear neighbourhood so there may be other objects in its orbit around the sun |
|
|
Asteroids |
Made of metals and rocky material and orbit the sun in highly elliptical orbits(oval shaped orbits) |
|
|
Comets |
Similar to asteroids but made up of rocky material, dust and ice. They vaporise as they approach the sun and produce a distinctive tail |
|
|
When was the solar system formed |
4.6 billion years ago |
|
|
How the solar system was formed |
From a nebula which collapsed under its own gravity so it got denser and rotated rapidly and transferred GPE to KE, core began to form dense protostar as collisions meant KE converted to thermal energy |
|
|
Nebula |
Cloud of gas and dust which if massive enough can collapse under gravity to form a protostar |
|
|
Protostar |
The early stage in the formation of a star, the bit before nuclear fusion occurs |
|
|
When can nuclear fusion occur |
When the sun’s core is hot and dense enough |
|
|
Reactions that occur during the nuclear fusion which forms a star |
1. Hydrogen nuclei join together to form a helium nuclei 2. Energy is transferred by radiation |
|
|
How gravitational collapse is balanced by expansion(for the sun) |
Fusion energy: the sun is at equilibrium, gravity pulls it inwards and radiation pressure expands it outwards |
|
|
Orbital motion |
Gravity provides the force needed to maintain stable orbit of both planets around a star and also of moons and artificial satellites around a planet |
|
|
For an object to remain in a steady circular orbit |
It must be travelling at the right speed |
|
|
For an object to remain in a steady circular orbit |
It must be travelling at the right speed |
|
|
If satellite is moving too quickly |
Gravitational attraction is too weak so it moves off into space |
|
|
If satellite moving too slowly |
Gravitational attraction too strong and satellite will fall towards earth |
|
|
If satellite moving too slowly |
Gravitational attraction too strong and satellite will fall towards earth |
|
|
If they orbit at the same speed |
They have a stable orbit so will orbit in a fixed path |
|
|
When an object moves in a circle at constant speed |
Direction constantly changes which causes changes in velocity as velocity is a vector quantity |
|
|
An object will only accelerate if |
A resultant force acts on it |
|
|
An object will only accelerate if |
A resultant force acts on it |
|
|
Centripetal force |
Force needed for a circular motion which acts towards the centre of the object |
|
|
An object will only accelerate if |
A resultant force acts on it |
|
|
Centripetal force |
Force needed for a circular motion which acts towards the centre of the object |
|
|
The closer 2 objects are together |
The stronger the force of gravity between them |
|
|
The 2 orbits artificial satellites travel in |
Polar orbits and geostationary orbits |
|
|
The 2 orbits artificial satellites travel in |
Polar orbits and geostationary orbits |
|
|
Polar orbits |
Satellites over the earths poles which travel very close to the earth so at very high speeds |
|
|
Geostationary orbits |
Take 24 hours to orbit the earth so remain in the same part of the sky when viewed from the ground. They orbit higher so travel slower |
|
|
Formation of a star step |
Protostar, main sequence star If same size as sun - red giant star, white dwarf, black dwarf If bigger than son - red super giant star, supernova, either neutron star or black hole |
|
|
Emission spectrum |
Light from star does not contain wavelengths of the electromagnetic spectrum, elements in the star absorb some of the emitted wavelengths so dark lines are present |
|
|
Emission spectrum |
Light from star does not contain wavelengths of the electromagnetic spectrum, elements in the star absorb some of the emitted wavelengths so dark lines are present |
|
|
Spectra from distant galaxies |
Dark lines show an increase in wavelength, lines shifted towards the red end of the spectrum |
|
|
Red shift |
The change in wavelength of light from a distant star moving away from earth |
|
|
Red shift |
The change in wavelength of light from a distant star moving away from earth |
|
|
Why can astronomers see red shift in virtually all galaxies |
Due to the space between earth and the galaxies expanding which leads to increase of wavelength of light from these galaxies, shifting them towards the red end of the spectrum |
|
|
What does the amount of red shifted light from a galaxy |
How fast it is moving away from earth |
|
|
Reasons to support the big bang theory |
1. More distant galaxies have a greater red shift 2. CMBR is everywhere at a temperature of about -270 decrees celcius |
|
|
Reasons to support the big bang theory |
1. More distant galaxies have a greater red shift 2. CMBR is everywhere at a temperature of about -270 decrees celcius |
|
|
What is CMBR |
The remains of the thermal energy from the big bang spread thinly across the whole universe |
|
|
Dark energy |
An unknown form of energy, put forward as a solution to the problem of why the expansion of the universe is accelerating |
|
|
Dark energy |
An unknown form of energy, put forward as a solution to the problem of why the expansion of the universe is accelerating |
|
|
Dark matter |
An unidentified form of matter that accounts for galaxies rotating faster than their visible mass should cause |
|
|
Lifecycle of star step 1 |
Nebula forms massive clouds of dust and gas in space and gravity pulls them together |
|
|
Lifecycle of star step 1 |
Nebula forms massive clouds of dust and gas in space and gravity pulls them together |
|
|
Lifecycle of star step 2 |
Protostar, as mass falls together it heats and star is formed and nuclear fission occurs |
|
|
Lifecycle of star step 1 |
Nebula forms massive clouds of dust and gas in space and gravity pulls them together |
|
|
Lifecycle of star step 2 |
Protostar, as mass falls together it heats and star is formed and nuclear fission occurs |
|
|
Lifecycle of star step 3 |
Main sequence star, during stable phase of stars life the force of gravity holding star together is balanced by higher pressures due to the higher temperature |
|
|
Lifecycle of star step 4 |
Red giant star, when all H2 has been used up in fusion process larger nuclei begin to form and star may expand to become a red giant |
|
|
Lifecycle of star step 4 |
Red giant star, when all H2 has been used up in fusion process larger nuclei begin to form and star may expand to become a red giant |
|
|
Lifecycle of star step 5 |
White dwarf, when all nuclear reactions are over a small star like the sun may begin to contract under the pull of gravity so it fades and changes colour as it cools |
|
|
Lifecycle of star step 4 |
Red giant star, when all H2 has been used up in fusion process larger nuclei begin to form and star may expand to become a red giant |
|
|
Lifecycle of star step 5 |
White dwarf, when all nuclear reactions are over a small star like the sun may begin to contract under the pull of gravity so it fades and changes colour as it cools |
|
|
Lifecycle of star step 6 |
Supernova, a latger star with more mass than the sun at first will go on making nuclear reactions and get hotter, expanding until it explodes as a supernova, an exploding supernova throws hot gas into space |
|
|
Lifecycle of star step 4 |
Red giant star, when all H2 has been used up in fusion process larger nuclei begin to form and star may expand to become a red giant |
|
|
Lifecycle of star step 5 |
White dwarf, when all nuclear reactions are over a small star like the sun may begin to contract under the pull of gravity so it fades and changes colour as it cools |
|
|
Lifecycle of star step 6 |
Supernova, a latger star with more mass than the sun at first will go on making nuclear reactions and get hotter, expanding until it explodes as a supernova, an exploding supernova throws hot gas into space |
|
|
Lifecycle of star step 6 |
If mass is the same as sun at the start then it will become a neutron star or black hole |
|
|
Main sequence star |
A stable with balanced forces keeping it the same size all the time |
|
|
Main sequence star |
A stable with balanced forces keeping it the same size all the time |
|
|
During main sequence: |
1.Gravitational attraction tends to collapse the star 2.radiation pressure from fusion reactions tends to expand the star 3.forces caused by gravitational attraction and fusion energy are balanced |
|
|
Fusion reaction |
Hydrogen nuclei join to form helium nuclei |
|
|
Fusion reaction equation |
1/2H + 3/1H -> 4/2He + 1/0N |
|
|
elements heavier than iron formed in |
Supernova explosion of high mass stars |
