space physics Flashcards
Name six things that orbit the sun in our solar system.
things that orbit the sun in our solar system:
- the eight planets
- the dwarf planets
- natural satellites (eg. moons)
- asteroids (minor planets)
- comets (icy rocks that release gases)
- artificial satellites (eg. man-made, like TV satellites)
Name the eight planets in our solar system.
the eight planets:
- Mercury
- Venus
- Earth
- Mars (all above are relatively small, rocky plants)
- Jupiter
- Saturn
- Uranus
- Neptune (Jupiter to here are much larger)
What galaxy is our solar system part of?
Our solar system is part of the Milky Way galaxy.
What is a galaxy?
A galaxy is a large group of stars.
Describe the life cycle of smaller stars, like the sun.
life cycle of small stars:
1) stars begin as a cloud of dust and gas called a NEBULA
2) gravity causes this to collapse
3) as the particles move faster, the temperature rises to millions of degrees - this is a PROTOSTAR
4) if the temperature increases high enough, then the hydrogen nuclei fuse together to form helium nuclei - this is a MAIN SEQUENCE STAR, which lasts around 10 billion years
5) the hydrogen begins to run out, so the outward force due to nuclear fusion is less than the inward force due to gravity, so it collapses
6) this causes the temperature to increase, so the helium nuclei fuse to form heavier elements
7) the star expands - this forms a RED GIANT
8) when it stops fusing helium, it shrinks to a WHITE DWARF
9) it gradually cools down as there is no more fusion
10) eventually, it stops releasing energy and forms a BLACK DWARF
Describe the life cycle of larger stars.
life cycles of larger stars:
1) stars begin as a cloud of dust and gas called a NEBULA
2) gravity causes this to collapse
3) as the particles move faster, the temperature rises to millions of degrees - this is a PROTOSTAR
4) if the temperature increases high enough, then the hydrogen nuclei fuse together to form helium nuclei - this is a MAIN SEQUENCE STAR, which lasts around 10 billion years
5) when they run out of hydrogen, they expand into RED SUPER GIANTS
6) helium nuclei fuse together to form heavier elements
7) they stop carrying out nuclear fusion and explode - this is called a SUPERNOVA
8) the temperature becomes high enough to produce elements heavier than iron, and the supernova distributes the elements throughout the universe
- the remains of the star become one of two things:
9) NEUTRON STAR - neutrons densely packed together
9) BLACK HOLE - such high gravity that even light waves can’t escape it
What is the difference between circular and elliptical orbit? How are they achieved?
- circular orbit - perfect circle orbiting an object
- elliptical orbit - uneven circle orbiting an object (this is earth around the sun)
- they are both achieved due to the force of gravity
What is a geostationary satellite?
A geostationary satellite orbits once every 24 hours.
Why is there a constant change in velocity and acceleration for circular orbits, but a constant speed?
In circular orbits, gravity leads to a constant change in velocity and acceleration, but not speed as the direction is constantly changing.
What happens to the radius of the orbit as the speed increases? Why?
As the speed of a satellite increases, the radius of orbit decreases as the satellite needs a greater force of gravity to prevent it from flying off into space, so it needs to be closer to the force of gravity.
What is the Doppler effect?
the Doppler effect:
- if an object is moving towards you, the wavelength decreases and the frequency increases
- if an object is moving away from you, the wavelength increases and the frequency decreases
- this applies to sound and light
State the visible light spectrum.
visible light:
- red (lowest frequency, highest wavelength)
- orange
- yellow
- green
- blue
- indigo
- violet (highest frequency, lowest wavelength)
Describe red shift.
If a star moves away from us, due to the Doppler effect, the wavelength will increase and the frequency will decrease, so it will be shifted towards the red end of the electromagnetic spectrum.
- nearby galaxies have a small red shift
- further galaxies have a larger red shift
Describe how red shift provides evidence for the Big Bang theory. Who observed this?
Hubble observed that:
- most of the galaxies’ light was red shifted
- the further away the galaxy is, the more red shifted it is
so. .. - most galaxies are moving away from us
- the further away a galaxy is, the faster it is moving away from us
- therefore, the universe is expanding
- the Big Bang theory states that the universe began from a very small region that was extremely hot and dense
- this provides evidence for this as if they are moving away, they must have started from one specific point
What is dark matter and energy?
Dark matter and energy is undetectable in the universe. Scientists say this may provide reason for why the expansion of the universe is speeding up. However, this is not very understood at the moment.
