P2- Space Physics Flashcards
How many stars does our solar system have?
1
What is the 1 star in our solar system?
The Sun
What is the solar system?
All the stuff that orbits the sun
4 things that orbit the sun
1) Eight Planets
2) Dwarf planets
3) Moons
4) Artificial satellites
What are planets?
-Large objects that orbit a star
-Their gravity is strong enough to have pulled in any nearby objects apart from their natural satellites
The Terrestrial Planets
-First 4 planets: Mercury, Venus, Earth, Mars
-All made up of rock and metal
-Denser than Jovian planets
-Substantially smaller than the gas giants
Asteroid belt
-Lies between the orbits of Mars and Jupiter
-Made up of thousands of small rocks and ices
The Jovian Planets
-Last 4 planets: Jupiter, Saturn, Uranus, Neptune
-Mainly made of hydrogen and helium in gas form
-Less dense
-Have many moons orbiting them
What are dwarf planets?
Planet-like objects that orbit stars but don’t meet all the rules of being a planet
What are moons?
A type of natural satellite that orbits planets
What is the Milky Way?
-A massive collection of billions of stars held together by gravity
-Our solar system is a tiny part of the Milky Way galaxy
How was the sun formed?
A cloud of dust and gas (nebula) was pulled together by gravitational attraction
Simple life cycle of a star that is about the same size as the sun
Cloud of gas and dust (nebula) -> Protostar -> Main sequence star -> Red giant -> White dwarf -> Black dwarf
Simple life cycle of a star that is much bigger than the sun
Cloud of gas and dust (nebula) -> Protostar -> Main sequence star -> Red super giant -> Supernova -> Neutron Star OR Black hole
What is the life cycle of a star determined by?
The size of the star
Step 1 of the life cycle of a star (Prompt: Cloud)
Stars initially form a cloud of dust and gas called a nebula
Step 2 of the life cycle of a star (Prompt: Gravity)
-Force of gravity pulls the dust and gas together to form a protostar
-Temp rises as the star gets denser
-When temp is high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei giving huge amounts of energy, keeping the core of a star hot
Step 3 of the life cycle of a star (Prompt: Pressure)
-Long stable period where outward pressure caused by the nuclear fusion that tries to expand the star, balances the force of gravity pulling everything inwards
-In this stable period, it is called a main sequence star lasting several billion years
Step 4 of the life cycle of a star (Prompt: Hydrogen)
-Hydrogen begins to run out
-Star swells into either a red giant or a red super giant
-Surface cools so it becomes red
-Fusion of helium occurs
Step 5 of the life cycle of a star (Prompt: Unstable) (stars about the same size as the sun)
-Small to medium sized star like the sun becomes unstable, ejecting its outer layer of dust and gas
-Leaves behind a hot, dense, solid core called a white dwarf
Step 6 of the life cycle of a star (Prompt: Energy) (stars about the same size as the sun)
-As white dwarf cools down, it emits less and less energy
-When it no longer emits a significant amount, it is called a black dwarf
Step 5 of the life cycle of a star (Prompt: Elements) (stars much bigger than the sun)
-Big stars glow brightly again
-Undergo more fusion and expand and contract several times
-Form elements as heavy as iron in various nuclear reactions
-Eject these elements into the universe to form new planets and stars
-Stars and their life cycles produce and distribute all naturally occurring elements
Step 6 of the life cycle of a star (Prompt: Dense core) (stars much bigger than the sun)
-Exploding supernova throws outer layers of dust and gas into space leaving a very dense core called a neutron star
-If the star is massive enough, it becomes a black hole
What is a satellite?
Any celestial object orbiting the Earth or any other planet
Uses of satellite
-Communication
-Space exploration
-Weather monitoring
-Navigation (GPS)
-Spying
What happens in an orbit?
-The force of gravity always acts towards the centre of the orbit so the orbital speed of the planet increases
-The velocity of the planet or satellite acts tangential to the orbit and is constantly changing
What allows planets and satellites to maintain circular orbits?
-Gravitational force acts as the object’s centripetal force
-The presence of a centripetal force allows for the object to maintain its circular orbit
What happens if you launch artificial satellites too fast?
It will fly off into space
What happens if you launch artificial satellites too slow?
It will crash back to earth
What is a geostationary orbit?
An orbit that takes 24 hours
What is the Red shift?
-There is an observed increase in the wavelength of light from most distant galaxies
-Further away the galaxies, faster they are moving and the bigger the observed increase in wavelength
What does the Red shift suggest?
-The source of light is moving away from us
-Distant galaxies are moving away from us very quickly
-More distant galaxies have greater red shifts than nearer ones
What is the conclusion of the Red shift?
The whole universe is expanding
What theory does the Red shift support?
The Big Bang Theory
What is the Big Bang Theory?
-Initially, all matter in the universe occupied a very small space
-This tiny space was very dense and hot
-Then it ‘exploded’ and space started expanding (expansion is still going on)
What do Observations of supernovae from 1998 show?
Distant galaxies are moving away from us faster and faster
What do scientists currently think the universe is mostly made up of?
-Dark matter
-Dark energy
2 examples of why there is still much about the universe that is not understood
-Dark mass
-Dark energy
How are elements distributed throughout the universe?
Through the explosion of a supernova
How are elements heavier than iron produced?
In a supernova
Explain why the radius of orbit must change if the speed changes, for a stable orbit
-Higher speeds= Object requires higher centripetal force
-For a greater centripetal force, gravitational force must increase
-Achieved by radius of orbit being reduced
Explain how the force of gravity acting on a satellite affects its speed and velocity
-Force can alter its velocity since direction is continually changing
-Can’t cause a change of speed since there is no force component in the direction of motion
