topic 7 astronomy Flashcards
what is the equation for weight
mass x gravitational field strength
what are factors of gravitaitional strength
the mass of the body creating the field and distance for the mass
number of planets in solar system
8 Mercury, venus, earth, MArs, jupiter, saturn, uranus, and neptune
name other things in solar system other than planets
planet’s natural satellites (moon), dwarth planets, asteroids and meteores
Planets in order
Mercury, venus, earth, MArs, jupiter, saturn, uranus, and neptune
how has ideas of solar system changed
1)Geocentric model ( everything orbited earth in perfect circles)
2) Heliocentric ( sun at centre of solar system)
3)
argument against geocentric model
Galileo observed moons around jupiter that didn’t move from their position so wasn’t orbiting around earth
describe orbit of Planets, moons, comets
Almost circular orbit.
Object in circular orbit at a constant speed in constantly accelerating.
Causes a centripetal force.
Usually would cause object to fall towards it but since already moving just changes it’s direction.
Keeps accelerating towards what it’s orbiting but instantaneous velocity keeps it travelling in a circle.
how ( for a stable orbit) change in speed leads to change in radius.
The closer to a mass you are, the faster you need to move. So, when speed changes, the size of the orbit changes as well. Faster-moving objects will move with a smaller radius than slower-moving ones.
compare steady state theory and The big bang theory
steady state:
1) says universe has always existed as it is now and will always do so
2)as Universe expands new matter is constantly created
3) density of universe is roughly the same
4) no beginning or end
Big bang:
1)All matter in universe occupied a small space
2) very dense and hot
3) It “exploded”
4) gives finite age ( 13.8bn years)
how does redshift and cosmic microwave background radiation support the big bang
Red shift: objects are moving away from the observer as the universe expands. This can be explained by both theories.
CMB: Low frequency electromagnetic radiation from all parts of universe. Evidence of universe having a beginning as radiation released form the “explosion”
Only supporting big bang theory
which theory is used today
Big bang as there is more evidence for it with CMB
why will there be change in observed frequency and wavelength from a moving wave source from observer
The Doppler effect-
same effect as the vrr-oom from a racing car. The noise sounds lower pitch when traveling away from you because it drops in frequency.
sound waves on a stationary car are equally spaced. Nut for a moving car the wavelengths are longer at back than front.
Describe the red-shift in light recieved from galaxies a different distance from the earth
Red shift: As galaxies move away the element produced by them ,absorb different light frequencies.
Each element produces specific patterns in the visible part of the EM spectrum as black lines.
Light from distant galaxies we see same pattern but at slightly lower frequencies.
There’s an observed increase in the wavelength of light and pattern shifted towards the red end of the spectrum.
why does red-shift provide evidence for the universe expanding
measurements of red-shift suggests that all the distant galaxies are moving away from us very quickly- same reading every direction you might look.
More distant galaxies have greater red shift larger increase in wavelength.
More distant galaxies are moving away faster than nearer ones.
why does the discovery of CMB made the big bang theory the current accepted theory
as red-shift is explained by both steady state and Big Bang theory where as CMB is only explained by BIg bang
Describe the evolution of a sun
1) Nebulla (cloud of dust and gas)
2)
