6 Space Flashcards
Earth
Rotates about its axis once every 24 hours
Earth orbits the sun every 365 days
The earth is around 1.5x10^11m away from the sun
Seasons and day/night
Seans are that since the planet is on a tilt in winter it is further away from the sun than in summer meaning it receives less light and heat.
This also means that in the winter the days are shorter due to the tilt facing away from the sun
In the summer It is tilting towards the sun meaning longer days
Orbital speed
v=2πr÷T
T=period
V= orbital speed(m/s)
r= radius(m)
Moon phases
New moon- ! waxing
Cresent
Quarter
Gibbous
Full moon- ^ waning
Solar system
In order from the Sun, these are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Minor planets also orbit the Sun and include dwarf planets and asteroids in the asteroid belt.
Dwarf planets are small, rocky bodies orbiting the Sun, but they are not big enough to be called planets.
The asteroid belt consists of large rocks called asteroids, which orbit the Sun between Mars and Jupiter.
There are also smaller bodies in the Solar System, such as comets and natural satellites.
A natural satellite is an object that orbits a planet or another body that is larger than itself.
Natural satellites are not man-made.
Solar system formation
Accretion model requirements:
Dependent on gravity
The presence of many different elements
Rotation of material into an Accretion disc
Evidence:
Organisation of our solar system, position and density of the 8 planets Planets have elliptical orbits so the distance from the Sun varies.
Star
A star is a ball of gas which radiates energy in the form of electromagnetic waves.
Stars come in different sizes, but they are usually (unless they are dying) made of hydrogen and helium.
Nuclear fusion in stars
Inside a star, hydrogen atoms are joined together with enough force to make them stick together (or fuse) into helium atoms.
This reaction produces a lot of energy, and this energy is released from the star in the form of electromagnetic waves.
However, this is only true of stable stars.
As a star gets older, it starts to run out of hydrogen and so it has to fuse other things together.
At this point it starts to become unstable.
Galaxies
Galaxies are collections of billions of stars, all orbiting around a galactic centre which is usually a black hole.
Calculate exactly how far a lightyear is
A light year is the distance travelled by light waves through the vacuum of space in one Earth year.
The speed of light is 3 × 108 m/s.
Converting one year into seconds:
1 year=365×24×60×60=31536000 s
Rearranging speed=distance/time
gives:
s=vt=3×108×31536000=9.5×1015 m
One light year is approximately 9.5 × 1015 m, or 9.5 trillion km
The life cycle of stars
All stars are born from interstellar clouds of gas and dust. The element hydrogen must be present in the cloud for a star to form.
Because of gravity, the interstellar cloud starts to collapse upon itself and clump together. Temperature increases because hydrogen nuclei start fusing. As gravity pulls in more material, the temperature increases further. At this stage, the star is called a protostar.
Then a Main sequence star is formed
(–> Red giant, –> White dwarf)
Or a Red super giant is formed
–> a supernova
Then a Nuetron star or Black hole is formed
Redshift
The wavelength of light will appear longer when the source is moving away from us
Light from every galaxy is redshifted.
And the further away the galaxy is from Earth, the more its light is redshifted.
It means the galaxy is moving away from us.
The more the light is redshifted, the faster the galaxy is moving away from us.
All the galaxies we can see are moving away from each other, and the further away they are from us, the faster they are moving.
Hubble constant
Is the ratio of an object’s speed in which it is moving away from the Earth, To its distance from the Earth
Ho=V÷d
V= receding speed(m/s)
d= distance from Earth(m)
Ho is 2.2x10^-18 per second(/s)
To calculate the age of the universe(the time it has been expanding)
S=D÷T = T=D÷S,
Ho=S÷D = 1÷Ho=D÷S
1÷Ho = 1÷2.2x10^-18(s) = 14 billion years
Cosmic microwave background radiation
shortly after the Universe was formed/after the Big Bang
Can be detected at all points in space
When the universe was formed large amounts of EM radiation were emitted.
As the universe expanded the radiation redshifted to the microwave end of the spectrum
