Option D Astrophysics (SL) Flashcards
how many planets are there in our solar system
8
name the planets in order
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
My Very Enthusiastic Mother Just Served Us Noodles
what is the hottest planet
venus
what are asteroids
lumps of rock mostly found between Mars and Jupiter in the astroid belt
what are comets
- they are made of dust and ice
- take hundreds of years to orbit the sun
- they start to melt when they get close to the sun, this make a tail
What is a planetary system
a group of planets orbiting a sun
what are binary stars
a pair of stars orbiting their common centre of mass
how can binary stars be detected
- visual - can be seen as two seperate stars
- eclipsing - detected by periodic variations in brightness as one star obscures the other
- spectroscopic - detected by changes in the wavelength of light received from each star (due to Doppler effect)
what is a stellar cluster
a close group of gravitationally bound stars, gas and dust
what is a globular stellar cluster
- contains about 10,000 – 100,000 stars
- symmetrically arranged and more closely packed in the centre.
- contains OLD stars
what is open stellar cluster
- contains several hundred stars
- irregular in shape
- contains YOUNG stars
Average distance between starts within a galaxy/average distance between galaxies =
10^-6
10^-6 =
Average distance between starts within a galaxy/average distance between galaxies
how can stars exist
singly or as binary stars
what is a galactic cluster
a group of galaxies gravitationally bound together
what is a supercluster
a larger group of galactic clusters
what is nebulae
an intergalactic cloud of dust and gas
what are constellations
- where certain stars appear to make patterns in the sky.
- it is important to realise that these stars are not necessarily close to each other.
what measurement do we use in the solar system
astronomical unit (AU) = 1.5x10^11m
what measurement do we use outside the solar system
light year = 9.46x10^15m
what is stellar parallax used for
- to find the distances to stars we see in the night sky
- it is used to determine the distance of stars relatively close to Earth (100 parsecs is max distance)
how does stellar parallax work
- the star’s apparent position relative to background stars is noted at 6 month intervals
- using trig: tan p = earth-sun distance÷sun-star distance
- as p is a very small angle, tan p = sin p = p (in radians)
- the angle p is so small it is measured in arc-seconds (1/3600th of a degree)
- using d (parsec) = 1/p(arcsecond)
definition of parsec
the distance at which the angle subtended by the radius of the Earth’s orbit is one arc-second
what is parallax angle
half of the observed angular displacement of the star