P16 - Space Flashcards
Explain how the Sun was formed:
-cloud of gas and dust (nebula) pulled together by gravitational attraction and forms a protostar
-friction between particles increases thermal energy, until there is enough to cause fusion reactions
-this leads to an equilibrium between the gravitational collapse of the star and the expansion of the star from the fusion reactions
✨hydrostatic equilibrium✨
Describe how the Sun will end its life from its current stage:
-expands into a red giant
-collapses to become a white dwarf
-cools into a black dwarf
What is the life cycle of a star dependent on? Draw a diagram to represent the paths any star will take throughout its life:
depends on mass
note that aqa ignores the planetary nebula step before white dwarfs
If you mention a supernova, what should you also say?
the star explodes
How did the heavier elements in the universe form?
-fusion in stars can produce all elements up to iron
-anything heavier than iron is formed in supernovae, and the explosion distributes the elements throughout the universe
What allows satellites to maintain a stable orbits? Explain why their speed must be controlled too:
-gravity
-if the orbiting object’s speed changes, the radius of the orbit must also change (and vice versa)
As orbital radius increases, orbital speed must decrease
Explain why the satellite’s velocity changes as it orbits Earth:
-gravity causes the satellite to accelerate towards Earth
-the acceleration causes a change in direction
-velocity is a vector quantity and includes direction, meaning the velocity changes
Describe the orbits of 2 types of artificial satellites:
polar - orbits closely and quickly over the poles
geostationary - orbits around the equator at the same rate (24hrs for 1 orbit) as the Earth rotates, so relative to the ground it appears to be stationary
There is also a geosynchronous orbit, similar to geostationary but it has a different inclination rather than being just over the equator, which makes it appear to oscillate up and down
What are the uses of the 2 types of artificial satellites?
polar - weather monitoring, taking images of Earth’s surface, and military applications (spying)
geostationary - communications and satellite TV
What is red-shift? How does it change?
-the observed increase in wavelength seen by the light from distant galaxies that are accelerating away from us
-the further the galaxy is, the faster they are moving relative to us, and the bigger the observed increase in wavelength
What does the Big Bang theory suggest, and what is the evidence?
-the universe began from a very small region that was extremely hot and dense
-redshift
-observations of supernovae in 1998 and onwards
How does redshift provide evidence for the Big Bang?
it shows that space is expanding, implying objects used to be closer together
How did observations of supernovae provide evidence for the Big Bang?
it showed that space is expanding at an accelerating rate, as the more distant supernovae had a larger redshift
Explain how this data shows that the Universe began from a very small region:
-the furthest galaxies are moving the fastest
-this suggests that the Universe is expanding from a very small region
