P16-Space Flashcards
How is the solar system formed?
From dust and gas clouds gradually becoming more and more concentrated because of their gravitational attraction.
What is a protostar and how is it formed?
It is formed by particles in clouds being pulled together by their own gravitational attraction so the particles speed up. The clouds then merge together and become more and more concentrated forming a protostar.
What happens once a protostar becomes denser?
The particles speed up and collide more, transferring energy form the kinetic to thermal energy store. Once it becomes hot enough the nuclei of the hydrogen atoms fuse and form helium, releasing energy and making it shine.
What happens to objects too small to become stars?
They are attracted by a protostar to become planets orbiting the star.
What is a main sequence star?
A star that radiates energy because of hydrogen fusion in the core.
How does the fusion in the core continue?
Energy released in the core keeps the core hot so the fusion continues. This spills out radiation from the core in all directions.
Why is a star stable?
This is because the forces within are balanced. The force of gravity inwards makes the star contract and the radiation of the nuclear fusion causes the star to expand.
When do stars become unstable?
When they have no more hydrogen nuclei that they can fuse together.
What is the life cycle of a star about the same mass as the sun?
Protostar - main-sequence star - red giant- white dwarf - black dwarf
What is the life cycle of a star with a larger mass than the sun?
Protostar - main-sequence star - red supergiant - supernova - neutron star(or black hole if enough mass)
How were all light elements formed?
Through fusion in stars, when it becomes a red giant fusing the helium atoms and other small nuclei into large nuclei.
What is the future of the sun?
It will eventually become a black dwarf.
What is a supernova?
The explosion of a red supergiant after it collapses.
What is left after a supernova?
It compresses the core of the star into a neutron star, which is dense and made only of neutrons. If it is big enough it becomes a black hole instead.
What does the force of gravity do to a planet and satellites?
It keeps the planet moving along the sun’s orbit and it makes sure the satellite moves along the earth’s orbit.
Where is the force of gravity on an orbiting body in a circular orbit directed?
Towards the centre of the circel.
As a body in a circular orbit moves around the orbit what occurs?
The magnitude of its velocity(speed) does not change but direction is continually changing and always at right angles to the direction of force. This means it experiences acceleration to the centre of the circle.
What must an object to stay in orbit at a particular distance?
Must move a particular speed round a larger body.
What happens the further a satellite is from the earth or a planet is from the sun?
The less particular speed needed for it to stay in circular orbit as the force is weaker. The longer the orbiting body takes to move around the orbit once as the orbit is bigger and moves slower.
What is a red shift?
It is when the light waves are stretched out if the star or galaxy is moving away from you, so the spectrum of light is shifted towards the red part of the spectrum.
What is a blue shift?
It is when the light waves are squashed together if the star or galaxy is moving towards you, reducing the wavelength moving the spectrum of light towards the blue part of the spectrum.
What is the relationship between speed of the galaxy and size of the shift?
The faster a star or galaxy is moving. the bigger the shift is.
What did Hubble discover?
The light from distant galaxies was red-shifted and the further a galaxy from earth, the bigger the red shift is. He concluded that due to distant galaxies moving away from earth, the universe is expanding.
What did the big bang theory state?
The universe is expanding after exploding suddenly from a very small, dense section and that space, time and matter were created in the Big Bang.
What is the evidence for the big bang?
The scientists detected microwaves coming from every direction in space, and this detection of cosmic microwave background which is electromagnetic radiation which was created in the Big Bang.
What is dark matter?
It i missing mass in the galaxy that cannot be seen.
