P8 - Space Flashcards
Life cycle of stars, solar systems, orbits, red shift, big bang
The Life Cycle of Stars -
What is the life cycle of a star?
- Form from cloud of dust and gas (nebula)
- force of gravity pulls dust + gas together to form protostar (temp rises as star dense and more particles collide)
- When temp high enough, hydrogen nuclei undergo nuclear fusion form hellium nuclei (give out lots of energy keeping core of star hot) + star born
- Star enter long stable period (outward pressure = gravity inwards) called main sequence star (7 billion years eg Sun)
- Hydrogen begins to run out, star swells into red giant (if small star), red super giant (if large star), fusion of helium + other elements occurs, heavier elements (up to iron) created in core of star.
- small to medium star - unstable + ejects outer layer of dust and gas leaves behind white dwarf
- White dwarf cools down (emits less and less energy) until becomes black dwarf
- Big stars - glow brightly and undergo fusion + expand and contract several times, form elements as heavy as iron in nuclear reactions
- Eventually explode in supernova (form elements heavier than iron and eject them into universe form new planets and stars)
- Exploding supernova throws ouer layers of dust and gas into space leave neutron star. If star massive enough, become black hole (dense point in space where no light can escape)
The Life Cycle of Stars -
What is a brief summary of the life cycle of a star the same size as the Sun?
Nebula –> protostar –> main sequence star –> stars same size of sun –> red giant –> white dwarf –> black dwarf
The Life Cycle of Stars -
What is a brief summary of the life cycle of a star bigger than the Sun?
Nebula –> protostar –> main sequence star –> stars bigger than Sun –> red super giant —> supernova –> neutron star –> black hole (if star massive enough)
The Solar System and Orbits -
What is the solar system?
All the stuff that orbits the Sun
The Solar System and Orbits -
What are examples of things that orbit the Sun?
- Planets
- Dwarf planets
- Moons
- Artificial satellites
The Solar System and Orbits -
What is a planet?
Large object that orbits a star
The Solar System and Orbits -
How many planets are there in our solar system and their order?
8
mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
The Solar System and Orbits -
What does it mean if the planets are large enough to have ‘cleared their neighbourhood’?
Their gravity is strong enough to have pulled in any nearby objects apart from their natural satellites
The Solar System and Orbits -
What are dwarf planets?
Planet like objects that orbit stars (don’t meet all rules for being a planet)
The Solar System and Orbits -
What do moons do?
Orbit planets
The Solar System and Orbits -
What are moons?
Natural satellite
The Solar System and Orbits -
What are artificial satellites?
Satellites humans have built (generally orbit earth)
The Solar System and Orbits -
What galaxy is our solar system a part of?
the Milky Way
The Solar System and Orbits -
What is the Milky Way?
Massive collection of billions of stars held together by gravity
The Solar System and Orbits -
What is a satellite?
An object that orbits a second, more massive object
The Solar System and Orbits -
What does gravity provide?
The force that creates orbits
The Solar System and Orbits -
What does it mean if an object is travelling in a circle and constantly changing direction?
constantly accelerating and constantly changing velocity
The Solar System and Orbits -
What does there have to be acting on an object for it to accelerate?
Must be a force acting on it (force directed towards centre of circle)
The Solar System and Orbits -
What does the force causing the moving object to do?
Change direction
The Solar System and Orbits -
What keeps the object travelling in a circle?
The object keeps accelerating towards what’s it’s orbiting but instantaneous velocity (at right angles to acceleration) means it keeps travelling in a circle
The Solar System and Orbits -
What is the force that helps the object to stay travelling in a circle provided by?
Gravity between the planets and the Sun (or between planets and the satellites)
The Solar System and Orbits -
What does the size of the orbit depend on?
The objects speed
The Solar System and Orbits -
What happens to the gravitational force the closer you get to the star or planet?
Get stronger
The Solar System and Orbits -
What does a stronger force mean in terms of how fast object needs to travel to remain in orbit?
stronger the force, faster orbiting object needs to travel to remain in orbit.
The Solar System and Orbits -
What happens if the speed of an object in a stable orbit changes?
the size (radius) of it’s orbit changes
eg faster moving objects move in stable orbit with smaller radius than slower moving objects
Red Shift and the Big Bang -
What is the evidence that galaxies are moving away from each other?
- light from distant galaxies wavelength has increased
- wavelengths have all shifted towards the red end of the spectrum (red shift)
Red Shift and the Big Bang -
What does red shift suggest?
The source of the light is moving away from us.
Red Shift and the Big Bang -
What do measurements of red shift indicate?
distant galaxies are moving away from use very quickly
Red Shift and the Big Bang -
What do more distant galaxies have in terms of red shift to nearer galaxies?
Greater red shift than near galaxies
Red Shift and the Big Bang -
What does greater red shift of far galaxies mean?
Means that far galaxies are moving away faster then near galaxies
Red Shift and the Big Bang -
What is the overall conclusion made due to red shift?
Whole universe is expanding
Red Shift and the Big Bang -
What is the Big Bang Theory?
- all matter in the universe occupied a very small space
- then exploded
- space started expanding and expansion still going on
Red Shift and the Big Bang -
What do scientists currently think the universe is mostly made up of?
- dark matter
- dark energy
Red Shift and the Big Bang -
What does dark matter not do?
Emit electromagnetic radiation
Red Shift and the Big Bang -
What is dark matter?
Name given to unknown substances which holds galaxies together
Red Shift and the Big Bang -
What is dark energy thought to be responsible for?
Accelerated expansion of the universe
