Space Flashcards
Within our solar system there is:
- One star, the Sun
- 8 planets and dwarf planets which orbit the Sun
- Moons (natural satellites that orbit planets)
What is a moon?
A natural satellite that orbits a planet.
How do stars such as the Sun form?
- Stars form from clouds of dust and gas called a nebulae.
- In a nebula the gas is mainly hydrogen.
- Gravity causes the cloud of dust and gas to collapse to form a protostar.
- As the dust particles move faster, the temperatures rise very high.
- If the temp. of the protostar gets high enough, hydrogen nuclei can now join together to form helium via nuclear fusion which releases a lot of energy.
- Now the protostar has turned into a star.
What is a galaxy?
The solar system is a just a tiny part of:
A massive group of stars.
The Milky Way galaxy.
In a nebula what is the main gas?
What is a nebula?
Hydrogen
A cloud of dust and gas.
What is a protostar?
A collapsing ball of hot gas and dust.
When a star undergoes nuclear fusion describe the forces exerted within the star:
There are two forces exerted within the star:
- The forces due to energy from nuclear fusion acting outwards on the star. (causing the star to expand)
- The forces due to gravity acting inwards on the star. (causing star to collapse)
^Because these two forces balance each other out, the star could be said to be at equilibrium.
Describe the life cycle of stars that are about the same size as the Sun:
Nebula
Protostar
Main sequence star
Red giant
White Dwarf
Black Dwarf
- Stars form from clouds of dust and gas called nebula where the gas is mainly hydrogen.
- Gravity causes the nebula to collapse.
- As the dust particles move faster, the temperatures rise to millions of degrees Celsius to produce a cloud of hot dust and gas called a protostar.
- If the temperature of the protostar gets high enough, hydrogen nuclei can join tg to form helium nuclei by nuclear fusion.
- At this point the protostar has turned into a main sequence star.
STARS THAT ARE ABT THE SAME SIZE AS THE SUN:
- In the main sequence star the hydrogen begins to run out so the outward force due to fusion energy is less than the inward force due to gravity.
- This causes the star to collapse inwards resulting in its temp increasing.
- Now helium nuclei fuse tg to make heavier elements and the star expands to form a red giant.
- When the red giant stops fusing helium it shrinks to form a white dwarf.
- Bc the white dwarf no longer carries out fusion it gradually cools down and stops releasing energy.
- This forms a black dwarf.
Describe the life cycle of stars that are much bigger than the Sun:
Nebula
Protostar
Main sequence star
Red super giant
Super Nova
Neutron star or black hole
- Stars form from clouds of dust and gas called nebula where the gas is mainly hydrogen.
- Gravity causes the nebula to collapse.
- As the dust particles move faster, the temperatures rise to millions of degrees Celsius to produce a cloud of hot dust and gas called a protostar.
- If the temperature of the protostar gets high enough, hydrogen nuclei can join tg to form helium nuclei by nuclear fusion.
- At this point the protostar has turned into a main sequence star.
- When they run out of hydrogen they leave the main sequence stage and expand to form Red super giants.
- At some point the Red super giant stops carrying out nuclear fusion and explodes to form a supernova.
- The temperature of a supernova is high enough to produce elements heavier than iron.
- When the supernova explodes, these elements are distributed throughout the universe.
- After the supernova the remains of the star can form either:
A neutron star; a star consisting of neutrons densely packed together.
A black hole; an area of such a great amount of gravity that not even light can escape.
Elements heavier than iron are only produced where?
In a supernova.
What force acting between the Sun and the Earth holds the Earth in its orbit?
Gravity.
True or false, gravity provides a force which allows planets and satellites to maintain their orbits?
True.
A force of gravity in circular object may lead to the change in velocity but not the change in speed, explain.
Velocity is the speed of the object in a given direction.
Bc the direction of the orbit is changing, even though its speed remains constant, the velocity is changing.
So the force of gravity is changing the velocity of the object, but not the speed.
If the speed of the satellite orbiting the earth changes, what must have changed?
The radius of its orbit.
If the speed increased, the radius of the orbit must have decreased + vv.
WHY?
- At a higher speed, the satellite needs a greater amount of gravity to prevent it flying off into the Earth.
- So by moving closer to the Earth, the satellite remains in a stable orbit bc the gravitational force on the satellite is greater.
What is meant by red-shift?
How does it prove the universe is expanding?
There is an observed increase in the wavelength of light from most distant galaxies.
The red-shift theory serves as evidence for the fact that the universe may be expanding. Bc the wavelength of light may be increasing so the distance of galaxies which are emitting the light to us are also increasing.
