Physics - stars and planets Flashcards
What is the order of planets from the sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
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What is a natural satellite?
A body that orbits a planet. For example, the Moon is a natural satellite of the Earth
What are comets?
Comets are balls of rock and ice. The ice melts as the comet gets closer to the Sun, producing its ‘tail’. They have highly elliptical or eccentric orbits.
What are asteroids?
Asteroids are large rocks that are mainly found in a belt between Mars and Jupiter. They are the remains of planets that failed to form due to Jupiter’s large gravitational pull.
How does a solar system form?
-A dense hydrogen-rich cloud of gas and dust contracts under gravity. As the gas gets compressed, its temperature increases and the dust cloud begins to spin.
-A protostar begins to form at the centre of this spinning dust cloud. Nuclear fusion starts, and a star is born.
-The planets begin to form from the swirling dust clouds around the star.
-Gravity is greater closer to the star. Most of the dense material in the dust cloud is attracted strongly and ends up here.
What are the inner four planets and how were they formed?
-The inner four planets (Mercury, Venus, Earth, and Mars) are rocky and have solid surfaces that can be walked on
-When the solar system formed, rocks (and other dense, heavy materials in the dust cloud such as iron and uranium) tended to gather closer to the Sun, and these materials combined together to form the inner planets.
What are the outer four planets and how were they formed?
-The outer four planets (Jupiter, Saturn, Uranus, and Neptune) are called gas giants.
-When the solar system formed, gaseous substances gathered together further away from the Sun and formed the gas giants.
What are planet diameters measured in?
Planet diameters are measured in metres and kilometres.
What are the distances between the planets and the Sun measure in?
-Distances between the planets and the Sun are measured in AU (Astronomical Unit).
-1 AU is the average distance between the Earth and the Sun and is approximately equal to 150,000,000 km (or 1.5 × 1011 m).
What is a light year?
The distance that light can travel in a year. 3 × 10^8 m/s
What is the life cycle of an low mass star?(simple)
1) Protostar
2) Average mass main sequence star
3) Red giant
4) White dwarf
5) Black dwarf
What is the life cycle of a high mass star?(simple)
1) Protostar
2) Massive main sequence star
3) Red super giant
4) Supernova
5) Black hole / Neutron star
What happens to stars when they are in their main sequence?
When stars are in their main sequence the forces on them balance. Outward radiation and gas pressure forces are balanced by gravity forces.
What is the life cycle of a low mass star?(extended)
1) Protostar - All stars start at a protostar. Once nuclear fusion takes they turn into a main sequence star.
2) Main sequence star - Overtime the forces acting on the stars become unbalanced. The forces become unbalanced when the hydrogen begins to run out, the star begins to fuse helium and then increasingly heavier elements until iron is formed and nuclear fusion stops and the star contracts under gravity. Low mass stars then for red giants.
3) Red giant - Red giant stars collapse to form a white dwarf star.
4) White dwarf - White dwarf stars gradually cool over time to form a black dwarf.
5) Black dwarf - The star stays at a black dwarf for the rest of its life cycle.
What is the life cycle of a high mass star?(extended)
1) Protostar - All stars start at a protostar. Once nuclear fusion takes they turn into a main sequence star.
2) Main sequence star - Overtime the forces acting on the stars become unbalanced. The forces become unbalanced when the hydrogen begins to run out, the star begins to fuse helium and then increasingly heavier elements until iron is formed and nuclear fusion stops and the star contracts under gravity. High mass stars form red super giants.
3) Red supergiant- Red supergiants quickly collapse, producing a giant explosion called a supernova.
4) Neutron stars - After the supernova high mass red supergiants form neutron stars which are very dense stars.
5) Black holes - After the supernova very high mass supergiants collapse with such force that they form black holes.
