space physics Flashcards
objects in the universe ( increasing size)
1) interstellar clouds of gas + dust
2) comets
3) meteors
4) moons
5) planets
6) stars
7) planetary systems
8) constelations
9) galaxies
10) clusters of galaxies
how old is the universe
13 billion years old
what is 1 light year in meters
9.47 x 10 ^15m
the earth spins on its axis once every
24 hours
earth tilt and seosons
the earth is tilted at a 23 degree angle, so the length of day and night may vary acording to the latitude. this changes through out the year.
why is H hotter in the summer
- there are more hours of sunlight and sun heat energy
- the sun has a greater elevation and its energy is spread over a smaller area, energy is more intense
- there is less atmosphere for the energy to pass through as the sun is higher in the sky
how long does it take for the earth to orbit the sun
365 days
time T=
3.156 x 10 ^ 7
avarage distance of sun to earth
1.5 x 10 ^11 m
orbital speed v=
2 pie r / T
the earth orbits in what shape
eclipse and when its closer to the usn it travels faster because it gains more potential energy which is transfered to kinetic energy. energy is conserved
how long does the moon take to orbit the sun
27 days
why does the moon have phases
depending on the angle between the sun, the moon and the earth, so different amounts of moon are seen.
what is a solar system
consists of a large mass star which planets orbit, asteroids and comets.
how does the sun produce its energy
it produces its energy ( light, thermal, infra red, and ultraviolet by nuclear fusion
what happens siince the suns mass is so great
planets and other bodies orbit it
what is the dominant force in a solar system
gravity- provides the centripetal force that makes the planets orbit the sun
eliptical orbits:
most planets orbit the sun in a eclipse. the sun is not at the centre
what is the effect of mass in gravitational force
the greater the mass the greater gravutational field strength
what is pluto
it is a dwarf planet, small and rocky
relation which orbital speed and distance
orbital speed decreases with increasing distance as the suns gravitaciona field strength decreases with increasing distance
why does the average surface temperature decrease as distance from the sun increases.
because they recieve less heat energy
what is the asteroid belt
rocks in different sizes, orbiting the sun between jupiter and mars
what are moons
natural satelites orbiting planets
why do we see moons?
because they reflect sun to us
what are comets
balls of rock and ice in very eliptical orbits around the sun ( comets tail points away from sun)
what are meteors
pieces of dust to large rocks which orbit around the sun, they burn due to friction when they enter our atmisphere and becomes a meteriorite when reaches earcth
how long ago did the solar system form
4.7 billion years ago
how did the solar system form
all the material, gas, dust, that made the sunn and the planets came from a giant star that exploded at the end of its lifetime in a supernova
what is a nebula in formation of solar system (formation of sun)
giant cloud of interstellar space and gas and dust. the gravitational force between them pulled it together and colapsed the cloud on itself. the cloud began to spin. the hydrogen gas at the centre was pulles together in such a small space that the temp increases so much that nuclear fussion startes. the sun was born
formation of planets in our solar system
remaining material began to be pulled together by gravity into clumps. the solar wind swept away lighter elements. this left only atoms with greater mass m, forming inner rocky planets
where the solar wind had less force, the lighter elements where pulled together due to gravitational force between them, forming 4 large gas planets
what does the sun consist of?
medium sized star made of mainly hydrogen and helium
why does the sun consist of hydrogen and helium?
because the centre of the sun is at the hugh temp of 15 million degrees celcius which gives a hydrogen nuclei enough kinetic energy to fuse together and release energy
how is energy from the sun radiated
infared, visibe light, and ultra violet regions- but all electromagnetic waves are emitted
what does it mean for stars to have luminosity
produce light
what is a light year
the distance travelled by light in the vacum of space in the time of 1 year ( 365 X 24 X 60 X 60)
what is 1 light year
9.5 x 10^15
what are galaxies
billions of stars sperated by vast distances
what is between stars and galacies
interstellar matter
length of milky way
10^5 light years
what does gravity do for stars
provides the centripetal force that allows the rotation of stars about the centre of the galaxy
star formation
intersellar cloud of gas-> hot-> protostar( hotter -> main sequence star( stabble) (hottest)
what is a protostar
the interstellar cloud is collapsing and temp is increasing due to internal gavitational attraction
stable star
the protostar becomes stable, because the inward gravitational force is balanced with the outward force dure to nuclear fusion in the high temperature core
what are red giants
large cool stard that are made when main sequence stars run out if hydrgen
low mass star lifecycle eg(sun)
main sequence star-> red gian ( fusion of helium)-> nebula+white dawrf
white dwarf
very dense, very hot, carbon or oxygen core, no fusion, cooling, size of earth, very small, cannot be seen by naked eye,
what does a white dwarf cool into
invisible black dwarf
high mass star
star bigger than sun will form a red super giant star when hydrogen runs out. it wil have fussion of higher elements but when they run out will be a massive supernova explosion. very dense neutron star is left behind and a nebulla
very high mass star
for a star much more massive than the sun, form a red super giant star when fusion stops, the even bigger supernova will resukt in a black hole and a nebula cloud.
what is a black hole
has so much density that it bends space time and not even light can escape from it.
what is a nebula from a supernova
contains hydrogen and heavier elements made in explosion. new stars can e formed in it
the universe is
expanding, galaxies are moving away from each other
big bang therory
the past universe was very small and very hot. all matter in the universe was in a sigle point of singularity- a point of infinate density and gravitational force.
red shift
observed light and other electromagnetic radiation emitted from most stars and galaxies that is detected on earth has a longer wavelength compared to a stationary point- this is because of redhsift
distance relation to recession speed
the further away from earth a galaxy ism the greater its recession speed
V= (2.2x10^18) x d
age of universe formula
T= 1/Ho
what is the universe beig cold evidence for
that it was very small and very hot before
how do cosmic microwave background radiation waves reach earth?
from all direction with equal intensity.
how did the wavlength change as universe expanded
wavelength increased, and now radiation is in electromagnetic spectrum.
evidence for the big bang
redshift from receading stars and gakaxies, the expading universe
