P16- Space Flashcards
5 things included in our solar system?
What galaxy is our solar system a part of?
The sun, 8 planets, dwarf planets, moons that orbit planets, and natural satellites
The Milky Way
How are stars formed?
Particles in clouds of dust and gas (nebula) are pulled together by gravitational attraction to form a protostar. The particles speed up and collide more, increasing the temperature. When hot enough the nuclei of hydrogen atoms fuse together to form helium nuclei. This nuclear fusion releases energy and creates a main sequence star.
How do stars reach equilibrium?
When do stars become unstable?
Nuclear fusion inside a star (radiation pressure) tries to make it expand, while gravity acts inwards trying to make the star contract. These are balanced.
When they have no more hydrogen nuclei that can fuse together
Lifecycle of stars with a similar size to the sun
Nebula–> protostar–> main sequence star–> red giant–> white dwarf–> black dwarf
What happens to a star (same size as Sun) between main sequence and end of the star’s life?
Star expands to become a red giant
Then collapse to become white dwarf
Then cool to become black dwarf
Lifecycle of stars larger than the Sun
Nebula–> protostar–> main sequence star–> red supergiants–> supernova–> neutron star/ black hole
If massive enough then is a black hole
How are naturally occurring (light) elements formed?
Why are they different?
How are naturally occurring (heavy) elements formed?
-Fusion in stars
Too much energy is needed to form heavy elements
-Supernova, then distributed across the universe when it explodes
What is a supernova?
The explosion of red supergiants after they collapse
What does gravity do to orbits?
What type of force is it?
Gravity allows planets and satellites to maintain their circular orbits
A centripetal force as it acts towards the centre of a circle e.g the Sun
Artificial satellite def?
A man-made object that orbits a planet
What effect does gravity have on a planet’s speed, velocity and acceleration? Why?
Speed doesn’t change as the gravitational force acts at right angles to the planet’s direction of motion, so no work is done on the planet.
Velocity changes as the gravitational force causes the planet to change direction in a circular orbit
Acceleration towards the centre of the Sun due to force of gravity
What is needed for an object to stay in a circular orbit?
The smaller body must move at a particular speed
How does the distance from Earth affect the required speed of a satellite?
The further away the satellite is, the lower the speed needed to stay in a circular orbit as the gravity is weaker
How does the distance from Earth affect the time it takes for the satellite to orbit once?
The further the distance, the longer the time taken for a single orbit as the circumference of the orbit is bigger
Relationship between speed and radius of an object in a circular orbit?
If speed of an object increases, radius will increase, causing the speed to decrease as it’s in a higher orbit
How to tell if a distant galaxy is moving away from you?
What is it called?
The light observed from it has longer wavelengths
Red-shift as the light is shifted towards the red part of the spectrum
How does the speed of a galaxy/star affect the shift?
How does the distance of a galaxy/star affect the shift and speed?
The faster the star/galaxy is moving, the greater the shift
The greater the distance, the greater the shift and speed
Why do scientists think the universe is expanding?
Light from distant galaxies was greatly red-shifted. Red shift is greater the further from Earth, so distant galaxies are moving away from Earth
The Big Bang theory says that..?
-The universe is expanding after exploding from a very small, hot and dense region
What is cosmic microwave background radiation?
High-energy radiation released after the Big Bang that now travels through space
What did observations of supernovae in distant galaxies suggest?
That distant galaxies are accelerating away from each other, potentially using dark energy
What is dark matter?
The missing mass from galaxies that increases their densities
