13 Astrophysics Flashcards
Universe
Large collection of billions of galaxies
Galaxy
Large collection of billions of stars
Our solar system
Milky Way galaxy
Gravitational field strength (g) increases when
Mass of source increases
Distance from source decreases
(G) earth > (g) moon because
Earths mass higher
Suns mass is far higher than earths but we are attracted to earth because
Distance to centre is smaller
Objects in orbits cannot
Escape gravity —> moves in circles
Objects in orbit speed and direction
Speed constant at all points
Direction different at all points
- therefore velocity is different at all points
Velocity to weight of objects in orbits
90 degrees from weight in opposite direction
Orbit of comets when CLOSE to sun
Gravitational field strength higher
Force on comet higher
Orbit is TIGHTER
Planets and moons orbit
Circular or slightly elliptical
Comets orbit
Highly elliptical
The Big Bang: universe began
14 billion years ago
The Big Bang
- created energy, space and time
- followed by expansion and cooling of space
Singularity
Tiny hot dense point that Big Bang began with
Evidence for Big Bang
- cosmic microwave background radiation
- red shift of galaxies
Cosmic microwave background (CMB)
- background radiation from all over Universe
- appears to be same in all directions
- this implies to all parts of the universe that were in contact at one point
- used to be gamma rays but wavelength has increased overtime
Universe was
Hotter a long time ago
Stationary wave sours emits
At constant wavelength and frequency
Is a source moves towards an observer
Wavelength decreases
Frequency increases
If a source moves away from observer
Wavelength increases
Frequency decreases
Redshift
Change in wavelength/reference wavelength
Speed of galaxy/speed of light
Greater distance from earth
Faster a galaxy moves
Greater redshift
More red
This implies expansion from single point
