Topic 8 - Space Physics Flashcards
What are the stages in the
life cycle of a star?
(much bigger than the sun) (6 stages)
- Cloud of Dust and Gas
- Protostar
- Main Sequence Star
- Red Super Giant
- Supernova
- Neutron Star OR Black Hole
What are the stages in the
life cycle of a star?
(about the same size as the sun) (6 stages)
- Cloud of Dust and Gas
- Protostar
- Main Sequence Star
- Red Giant
- White Dwarf
- Black Dwarf
What are the
first three stages of the life cycle of a star?
(explained)
u got this!! xx
- Stars initially form from a cloud of dust and gas called a nebula.
- The force of gravity pulls the dust and gas together to form a protostar. The temperature rises as the star gets denser and more particles collide with each other. When the temperature gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei. This gives out huge amounts of energy, which keeps the core of the star hot. A star is born.
- The star enters a long stable period where the 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’s called a main sequence star and it typically lasts several billion years.
What are the
next three stages of the life cycle of a star?
(explained) (a star much bigger than the sun)
- Eventually the hydrogen begins to run out. The star then swells into a red super giant. It becomes red because the surface cools. Fusion of helium (and other elements) occurs. Heavier elements (up to iron) are created in the core of the star.
- Big stars start to glow brightly again as they undergo more fusion and expand and contract several times, forming elements as heavy as iron in various nuclear reactions. Eventually they’ll explode in a supernova, forming elements heavier than iron and ejecting them into the universe to form new planets and stars. Stars and their life cycles produce and distribute all naturally occuring elements.
- The exploding supernova throws the other layers of dust and gas into space, leaving a very dense core called a neutron star. If the star is massive enough, it will become a black hole - a super dense point in space that not even light can escape from.
What are the
next three stages of the life cycle of a star?
(explained) (a star about the same size as the sun)
- Eventually the hydrogen begins to run out. The star then swells into a red giant. It becomes red because the surface cools. Fusion of helium (and other elements) occurs. Heavier elements (up to iron) are created in the core of the star.
- A small-to-medium-sized star like the Sun then becomes unstable and ejects its outer layer of dust and gas. This leaves behind a hot, dense, solid core - a white dwarf.
- As a white dwarf cools down, it emits less and less energy. When it no longer emits a significant amount, it is called a black dwarf.
What is a
planet?
a large object that orbits a star
they have to be large enough to have “cleared there neighbourhoods”, this means that their gravity is strong enough to have pulled in any nearby objects (apart from their natural satellites)
What is our
solar system?
all of the things that orbit our Sun
How many
planets are there in our solar system?
8
What is the
order of planets in our solar system?
[Sun]
My - Mercury
Very - Venus
Educated - Earth
Mother - Mars
Just - Jupiter
Served - Saturn
Us - Uranus
Noodles - Neptune
What is a
dwarf planet?
planet-like objects that orbit stars, but don’t meet all of the rules for being a planet
What is a
moon?
a type of natural satellite that orbits a planet
What are
artificial satellites?
satellites that humans have built
they generally orbit the Earth
What is the
Milky Way Galaxy?
a massive collection of billions of stars that are held together by gravity
our solar system is a tiny part of this
How does
gravity provide the force that creates orbits?
(5 steps)
- If an object is travelling in a circle it is constantly changing direction, which means it is constantly accelerating.
- For an object to accelerate, there must be a force acting on it. This force is directed towards the centre of the circle.
- This force would cause the object to just fall towards whatever it was orbiting, but as the object is already moving, it just causes it to change direction.
- The object keeps accelerating towards what it’s orbiting but the instantaneous velocity keeps it travelling in a circle.
- The force that makes this happen is provided by the gravitational force between the planet and the Sun.
(or between the planet and its satellites)
How does
distance from star/planet affect orbits?
The closer you get to a star or planet, the stronger the gravitational force is. So, the stronger the force, the faster the orbiting object needs to travel to remain in orbit.
For an object in a stable orbit, if the speed of the object changes, the size of its orbit must do so too. Faster moving objects will move in a stable orbit with a smaller radius than slower moving ones.
