P8 Space physics (triple only) Flashcards
What two things are in balance in a main sequence star?
Radiation pressure and gravity.
Name the planets in the Solar System from the Sun outward.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
What does the Solar System consist of?
The Sun and all the planets, dwarf planets, asteroids and comets in orbit around it.
Why is dark matter thought to exist?
There doesn’t seem to be enough visible matter to account for the formation and movement of the galaxies.
Why is dark energy thought to exist?
Recent observations of supernovae suggest that the expansion of the universe is accelerating. This is acceleration is thought to be caused by dark energy.
What are the main pieces of evidence for the Big Bang theory?
The redshift exhibited by light from distant galaxies and the cosmic microwave background radiation (CMBR).
Light from distant galaxies is shifted towards the red end of the spectrum (redshift).
What can we conclude from this?
The galaxies are moving away from us. The universe is expanding.
What happens when a main sequence star runs out of hydrogen in its core?
It expands to become a red giant.
How do stars produce energy?
By nuclear fusion in the core of the star.
What type of satellites are put into geostationary orbits?
Communication satellites.
What type of orbit would weather or spy satellites be put into?
Polar orbit.
What do we call the force that keeps an object moving in a circle?
Centripetal force. (In the case of a planet this would be the force due to gravity)
If an object has a non-circular orbit, why does its speed change as it orbits?
The force of gravity will be greater when the orbit takes it closer to the body it is orbiting.
Why is the velocity of an object moving in a circle is constantly changing?
Because its direction is constantly changing.
