Space Flashcards
List the life cycle of a star the same size as the sun
Nebula Protostar Main sequence star Red giant White dwarf Black dwarf
List the life cycle of a star much bigger than the sun
Nebula Protostar Main sequence star Red super giant Supernova Neutron star or black hole
Explain how a nebula becomes protostar
A nebula is clouds of dust and gas.
The force of gravity pulls them together to form a protostar
Explain how a protostar becomes a main sequence star
As the star gets denser, temperature rises and particles collide with eachother more. When the temperature is high enough, the star undergoes nuclear fusion, where hydrogen nuclei fuse to form helium nuclei. This gives our a lot of energy and makes the star form
Explain a main sequence star
The longest stage or a star where it is stable from the outwards pressure and onwards gravity balance eachother. The star continues to undergo nuclear fusion.
How does a main sequence star become a red giant or red super giant?
Eventually the hydrogen runs out so the star swells (as there is no longer as much outwards pressure which was caused from nuclear fusion). This swelling forms a red giant or if it is even bigger a red super giant. Fusion of helium and other elements occurs to make heavier elements up to iron.
What is a white dwarf?
a hot, dense, solid core left behind when a small/median sized star becomes unstable so sheds its outer layers after being a red giant
How does a red giant become a white dwarf?
The red giant becomes unstable so sheds out its outer layers of dust and gas to leave behind a white dwarf
How does a white dwarf become a black dwarf?
The white dwarf cools down, so that it emits less energy. When it can no longer emit a significant amount, it is known as a black dwarf.
What happens in a super red giant?
undergo lots of nuclear fusion, forming elements as heavy as iron
expand and contract several times
What is a supernova?
an explosion (of a super red giant) elements heavier than iron are formed from fusion, which are ejected into the universe to form new planets and stars
What is left behind after a supernova explosion?
a neutron star or a black hole
What is a neutron star?
a very dense core (left behind after the outer layers of dust and gas are thrown into the universe by a supernova)
What is a black hole?
an infinitely dense point in space (formed from a supernova if the star is massive enough)
What are the planets in our solar system?
in order of distance from sun
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
What are planets?
large objects that orbit a star that are large enough to have cleared their orbits (their gravity is strong enough to have pulled in any nearby objects)
What are moons?
a type of natural satellite that orbit planets
What is a satellite?
an object that orbits a more massive object
What are artificial satellites?
satellites that humans have built
What are orbits?
the paths objects take as they more around another object in space
What provides the force to create orbits?
gravity
How does a satellite stay in orbit around a circle?
to be travelling in a circle, its direction much be constantly changing, meaning it us constantly accelerating
the object is constantly changing velocity (but not speed)
for an object to accelerate, there must be a force acting on it coming from the middle of the circle (this force is gravity)
this force would cause the object to fall towards the object it’s orbiting but because the object is already moving, the force causes it to change direction
What does the size of an orbit depend on?
its speed
the stronger the force, the faster the orbit needs to travel in order to remain in orbit
What is red-shift?
The idea that there is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength.
This means that the universe is expanding as everything is gradually moving away from eachother.
What is the Big Bang Theory?
the theory that initially all matter in the universe started from a very small point (which was hot and dense)
this point started expanding and has continued expanding since
Name two examples of things scientists still know very little about in space
dark matter/mass
dark energy
What should be done to theories when new evidence is found?
test them and if the new evidence doesn’t fit it, either the theory needs to be changed or they need to create a new theory
