Astronomy Flashcards
What is the order of the planets?
Men - Mercury Very - Venus Easily - Earth Make - Mars Jelly - Jupiter Serve - Saturn Useful - Uranus Needs - Neptune
What was the geocentric model?
A model of the solar system where the Earth was at the centre with all the planets and the Sun moving around the Earth
What is the heliocentric model?
A model of the solar system with the Sun at the centre with all the planets orbiting the sun
What are natural satellites?
Satellites formed by natural processes, examples include planets, moons, comets
What are artificial satellites?
Satellites that are manufactured and launched into space
What are the different types of artificial satellites?
- Satellites in geostationary orbits (used for GPS)
- Satellites in low polar orbits (used for weather monitoring, millitary purposes etc.)
- Satellites that orbit and monitor the sun, other planets or asteroids in the solar system
What type of orbit do planets orbiting the sun move in?
Circular or near-circular orbits
What type of orbit do comets travel in?
Highly elliptical orbits
What happens to a comets speed as it gets further away from the sun?
It decreases because the gravitational force of the sun is weaker when it is further away
What is the big bang theory?
A theory of the universe that states that the universe started out as a tiny particle and expanded from this point to what it is today, the universe is still expanding today
What is the steady state theory?
A theory of the universe that states the universe has always existed and is expanding, creating new matter as it expands
What is red-shift?
When an object is moving away from us the wavelengths of light it’s emitting are stretched meaning they spectral lines will shift further towards the red end of the spectrum. The faster the object is travelling away from us the more the light is red-shifted.
Why is red-shift evidence for an expanding universe?
The furthest galaxies show more red-shift than the ones nearer to us
What is CMB (Cosmic Microwave Background)?
CMB is radiation that is present in the universe today, it is present everywhere and has a very low temperature. Because it is everywhere it suggests that it was there when the big bang happened and has moved with the expanding universe. The fact that it has a very low temperature is even more evidence for the big bang because the radiation would have originally been extremely hot. This suggests that it was present a very long time ago to have cooled that much
What is the Doppler effect?
Waves are have a longer wavelength and lower frequency when they’re moving away from us and they have a shorter wavelength and higher frequency
Describe the life-cycle of a low mass star
- The star starts off as a nebula (a cloud of dust and hydrogen gas)
- Nuclear fusion occurs to produce heavier helium nuclei and releases large amounts of energy
- The star now undergoes its main sequence, it spends most of its life in its main sequence
- When most of the hydrogen gas has been converted to helium the star expands and becomes a red giant
- Eventually all nuclear fusion stops due to the elements that cause fusion being used up, the star then collapses and becomes a white dwarf
Describe the life-cycle of a high mass star
- Follows the same stages as a low mass star until it starts undergoing nuclear fusion
- It then starts its massive main sequence
- When most of its hydrogen has been used up it becomes a red supergiant
- The star explodes and becomes a supernova
- If what remains after the explosion is less than 4 times the mass of the sun it will be pulled together by gravity to form a neutron star
- If it is more massive it will form a black hole
What is blue shift?
When the waves are moving towards us they’re squished so the spectral lines move towards the blue end of the spectrum, this is called blue shift
