Space physics Flashcards
What are the main parts of the solar system
The sun is at the centre of the solar system and all planets orbit the sun. The sun is a star. There are 8 main planets orbiting the sun.
Mercury, Venus, Earth and Mars are rocky planets. Jupiter, Saturn, Uranus and Neptune are gas planets.
Our dwarf planet is Pluto.
How are stars formed?
Stars start as gas called a nebula this is mainly hydrogen. Gravity causes the gas to collapse, as the dust particles move faster, the temperature rises millions of degrees. This collapsing cloud of hot gas is a protostar when the temperature gets high enough the hydrogen nuclei go through nuclear fusion to make helium. Now this is a star - which releases a huge amount of energy. When gravity and the energy released is equal the star is in equilibrium and maintains its shape.
What are moons?
They are natural satellites that orbit other planets. Most planets have one moon.
Where is a solar system located?
In the Milky Way Galaxy
What is a Galaxy?
A massive group of stars.
What are the two forces acting on a star?
For the star to maintain its shape there is two force acting on the star. Gravity - pulling the gas inwards and the energy from nuclear fusion acting outwards.
Describe the life cycle of a star
Nebula collapses due to gravity, the temperature rises (protostar) and nuclear fusion occurs (main sequence star). This lasts for millions of years when the hydrogen in a smaller star starts to run out the outward force is less than inwards force due to less energy being produced by nuclear fusion, so the star starts to collapse this then causes the stars temperature to rise. Now the helium nuclei fuse together to create heavier elements then the star starts to expand to form a red giant when the red giant stops fusing helium the star then begins to shrink to form a white dwarf. Because the white dwarf is no longer carrying out nuclear fusion it begins to cool down eventually it stops releasing energy and turns into a black dwarf.
How are elements formed in stars?
Through nuclear fusion, and when the heavier nuclei fuse.
What happens to a large star when it is dying?
It expands into a super red giant when they run out of hydrogen the helium nuclei fuse together to produce heavier elements but none heavier than iron. When nuclear fusion stops occurring the star explodes this is called a supernova. The temperature of this explosion is high enough to produce elements heavier than iron. This supernova then forms either a dense neutron star or a black hole which has such a large gravity that not even light can escape.
What are artificial satellites?
They are man made structures that are sent into orbit for different uses. Geostationary satellites are ones that orbit once every 24 hours and point to the same place of the Earth.
What is an orbit?
Planets orbit the Sun and the the force of gravity holds it in its orbit
Why does velocity change in a circular orbit?
In the case of circular orbits, the force of gravity is leading to a change in velocity but not speed as the direction is always changing. Velocity is a vector and speed is a scalar.
What is the relationship between speed and orbit?
When the speed of an object increases the size of the orbit decreases that is because at a higher speed a satellite needs a greater force of gravity to prevent it flying off into space.
What is the Red - Shift?
This is where wavelengths increase with distance due to parts of space becoming further way from us this means the wavelength increases and things appear more red. Because galaxies are moving away light waves are stretched so their observed wavelengths increase Galaxy’s further away have a bigger red-shift.
How does this provide evidence for the big bang?
Galaxy’s are moving at different speeds, some are moving faster than others so the distance between galaxy’s get bigger, so visible light takes longer to get to Earth so wavelength increases and moves along the colour spectrum making it appear more red. This proves the big bang as everything is expanding and moving away from a central point. The extremely dense small and hot point that expanded to create the universe.
