Space Physics Flashcards
(60 cards)
Orbital speed
2Πr/T
r - average radius of orbit
T - orbital period
Hubble constant
Ho = 2.2 x 10^-18
Formula hubble constant
v/d
Age of the universe
d/v = 1/Hubble constant
1 light year
9.5 x 10^15
Milky Way diameter
100 000 light years
How much time does Earth take to rotate on its axis?
once every 24h
Time taken for Earth to orbit Sun
365 days
Why do we experience seasons?
Slight tilt of earth’s axis
eg: December: northern hemisphere angled away from Sun (less sunlight, winter)
southern hemisphere towards Sun (more sunlight, summer)
How long does it take the Moon to orbit the Earth?
1 month
Order of planets from sun
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
How many stars in our solar system?
One, the Sun
What are some examples of minor planets that orbit the Sun?
minor planets, like dwarf planets (Pluto)
asteroids in the asteroid belt
What is a moon?
A natural satellite of a planet
What are some other smaller Solar System bodies?
comets and natural satellites
What are natural satellites?
an object that orbits a planet or another body that is larger than itself
What are comets?
balls of ice
orbit the Sun elliptically, and when they come close to the Sun, they heat up, and some of the ice evaporates, becoming a visible tail
How can you describe the four innermost planets in the Solar System?
rocky and small
How can you describe the four outermost planets in the Solar System?
large and gaseous
Explore the accretion model
Slowly, dust from interstellar clouds gradually clumped together because of its own gravity, began to spin as a disc, eventually most ignited, became the Sun.
Particles in remaining disc of dust began to clump together and grow into larger and larger chunks, pulled together by gravity.
Close to the Sun, high temp: materials like H and He (low BP) could not solidify into planets. Heavier elements like iron were the only ones that could form planets close to the Sun. Planets closest to Sun became rocky planets, hydrogen and helium pushed further out.
Further from the Sun: H and He condense into a liquid to form planets
Why is the accretion model called this?
Because the planets slowly gain (accrete) mass over time as their gravity attracts more material.
Effect of gravity on accretion model
The bigger the mass, the greater the gravitational field strength at its surface.
All the planets orbit Sun since it contains almost all the mass of the Solar System therefore a much stronger gravitational pull than anything else
Describe orbit shapes
Planets, minor planets and comets have elliptical orbits, Sun is not at centre (except when orbit is approx. circular)
Explain planet’s movements in an elliptical orbit.
Planets move faster when it is closest to the star.
Conservation of energy:
As planet gets closer to the star, GPE is converted into KE – so it moves faster.
As it travels away, its KE is converted back into GPE, so it slows down.
