Unit 8 - Space Flashcards
How are stars formed?
Dust particles attracted by gravity to form a nebula, until the nebula becomes hotter and more dense so fusion occurs. The star remains stable if the outwards pressure of fusion is equal to the inward force of gravity (main sequence). When a star dies, the outward pressure increases causing it to expand and turn into a red giant (if similar size to our sun) or a super red giant (if larger than our sun)
What happens when a red giant dies?
When fuel has run out, a white dwarf is formed. Over time, the white dwarf cools and forms a black dwarf
What happens when a super red giant dies?
It causes a supernova, where heavy elements and new nebula are created. This can lead to the formation of a very dense neutron star or a black hole.
What do satellites do?
Natural and artificial satellites orbit the Earth while geostationary satellites orbit above the same point on the equator
How are satellites accelerating?
Their orbits are circular, meaning while their speed is constant, their velocity is always changing due to a constant change in direction. This means they are accelerating but not getting faster.
What force is responsible for circular motion?
Centripetal force - always acts towards centre of orbit
(centripetal force and velocity are perpendicular)
What does it mean if satellites are in elliptical orbit?
Their speed increases when closer to Earth and vice versa.
What is the red shift?
Wavelengths of light from distant galaxies move to the red end of the spectrum: the wavelength is increasing as galaxies move away from us. The light from more distant galaxies is more red shifted, suggesting they move at a faster rate
What is the evidence for the big bang theory?
Due to the red shift showing all galaxies moving further apart from us, it suggests all galaxies at one point originated from the same position.
Cosmic background radiation - microwave radiation detected from every direction of space, which could be from the matter still cooling down from the big bang
