Astronomy Flashcards
What does geocentric mean?
That the sun and other planets orbit around the earth
What does heliocentric mean?
That planets orbit around the sun
What do bodies of lower mass orbit around?
Bodies of higher mass
Name 3 natural satellites
Planets, moons and comets
Name two types of artificial satellite
Satellites in geostationary orbits around the earth (GPS) and satellites in low polar orbits (weather, military, etc)
What is the difference between the Big Bang theory and the steady state theory?
Big Bang states that the universe started as a tiny particle 1.8 billion years ago, and continually expands. Steady state says the uni has always been here, and constantly expands
What is red-shift and how does it suggest that the universe is expanding?
When objects that emit light, such as galaxies, are moving away from us the light they emit is red shifted (greater wavelength and lower frequency). Since the furthest galaxies show more red shift than the ones closer to us, this proves that the uni is expanding.
What does blue-shifted mean?
A light source moving towards an observer will have a smaller wavelength and higher frequency. This is part of the Doppler effect
Describe the life cycle of stars
1) the cloud of dust and hydrogen gas (nebula) are pulled inwards by gravity.
2) they get hot enough for the nuclei to fuse. Nuclear fusion leads to a larger helium nuclei being produced. The star will give out light and is now a main sequence star.
3) when most of the hydrogen gas has been converted to helium, the star becomes a red giant.
4) When all fusion stops, the star collapses to become a white dwarf
What is the life cycle of a high mass star?
Same as normal star, however it forms a red supergiant and explodes as a supernova (which can leave black holes)
Why do comets travel more slowly farther away from the sun?
The gravitational force of the sun acting of the comet gets weaker as the comet gets further away, because the comet travels in an elliptical orbit, not a circular orbit
