Astrophysics Flashcards
What is a universe?
A large collection of billions of galaxies
What is a galaxy?
A large collection of billions of stars
Where is our solar system?
Milky way galaxy
What changes the force of gravity?
Mass and distance
What four things does gravitational force cause?
1) Moons to orbit planets
2) Planets to orbit the sun
3) Satellites to orbit the earth
4) Comets to orbit the sun
How do comets orbit?
Orbit the sun and are very elliptical
How do moons and planets orbit?
Slightly elliptical
What is the formula for orbital speed?
2 * Pie * orbital radius/ time period
How can stars be classified by the colour?
A blue star is the hottest, a red star is the coolest
Explain the evolution of stars?
1) Stars initially form from a cloud of dust and gas
2) The stars the enters a long stable period where the outward pressure caused by thermal expansion balances the force of gravity pulling everything inwards. This is a main sequence star
3) Eventually the hydrogen in the core begins to run out and the force due to gravity is larger than the pressure of thermal expansion. The star is compressed, until it is dense and hot enough that the energy created makes the outer layers of the star expand. This is a red giant
4) A small to medium sized star like the sun then becomes unstable and ejects its outer layer of dust and gas. This leaves behind a hot, dense solid core which is known as a white dwarf
What is the evidence for the big bang theory?
Measurements of the red shift suggest that all the distant galaxies are moving away
Change in wavelength / reference wavelength =
velocity of a galaxy/ speed of light
