6.Space physics Flashcards
Heliocentrism
The idea that the earth orbits around the sun
Orbit
A curved path that an object follows around another object. For example, the Earth orbits the Sun.
What are the two types of experiences on earth, caused by orbits?
- Day and night
- Seasons
What causes day and night?
The Earth spins on its axis once every 24 hours.
–> For approx, 12 hours a particular spot on the earth is facing away from the sun and experiencing night.
+ vice versa.
(the sun moving across the sky is actually jut the earth rotating to/away from it)
Why years/ seasons occur (basic reason)
The earth takes just over 365 days to complete one full orbit of the sun.
This is called a year.
Most countries (aside from those near the equator), experience four seasons.
This is because of the slight (23.5) tilt of the Earth’s axis.
Why does the tilt of the earth’s axis, cause seasons.
In December, the northern hemisphere is angled away from the sun + the southern hemisphere is angled towards the Sun.
This means that the northern hemisphere experiences less sunlight, whereas the southern hemisphere experiences more sunlight.
+ vice versa in June
Working out the circumference of an orbit (under the assumption it is perfectly circular)
C = 2πr
eg.
r = distance from the centre of the Earth to the centre of the Sun
C = circumference of earth’s orbit.
Working out the speed of an object in orbit. (eg. earth around the sun)
Speed = distance/time
Speed = 2πr/time
bc C = 2πr
What is the orbital period of earth
1 year
Why does the moon shine?
It reflects the light from the sun.
How long does it take for the moon to orbit the earth
1 month
What happens during the monthly orbit of the moon?
The moon travels around the earth whilst rotating at the same rate –> That way only one half of the moon is seen by the earth.
The sun shines towards the earth and the moon. Half the moon will always be lit up.
However, if the moon is between the earth and the sun, there will be no moon (known as a new moon) bc the earth can’t see the light reflected from the sun.
If the moon is behind the earth, all of the sunshine is being relfected by the moon –> Full moon.
The Solar System
Sun
Mercury
Venus
Earth
Mars
Asteroid belt
Jupiter
Saturn
Uranus
Neptune
Dwarf planets (eg. Pluto)
Comets also occur throughout the solar system.
Found in the milky way galaxy.
Order of the planets
My - Mercury
Very - Venus
Excellent - Earth
Mother - Mars
Just - Jupiter
Served - Saturn
Us - Uranus
Noodles - Neptune
Sun
All the planets, comets and asteroids in the Solar System orbit the Sun.
Mercury
Small rocky planet
1st planet in the solar system.
Venus
Small rocky planet
2nd planet in the solar system.
Earth
Small rocky planet.
3rd planet in the solar system.
Mars
Small rocky planet
4th planet in the solar system.
Jupiter
Gas giant planet
5th planet in the solar system
Saturn
Gas giant planet
6th planet in the solar system.
Uranus
Gas giant planet
7th planet in the solar system.
Neptune
Gas giant planet
8th planet in the solar system.
Dwarf planets
Small, rocky bodies orbiting the Sun, not big enough to be called planets. Pluto is an example.
Comet
Balls of ice which orbit the Sun in elliptical orbits. When they come close to the Sun they heat up and some of the ice evaporates, becoming a visible tail.
Asteroid belt
Millions of rocks, much smaller than planets, orbiting the Sun between Mars and Jupiter.
Dwarf planet Ceres can be found in the asteroid belt.
Natural satellite
An object that orbits a planet or another body that is larger than itself.
Natural satellites are not man-made.
Pattern of planet composition, moving out of the solar system.
Four planets closest to the sun = small + rocky
Four planets further from the sun = large + gaseous (primarily made of hydrogen and helium)
Interstellar clouds
Clouds of dust and gas found in space. Interstellar means between stars, so these clouds are found in deep space. They contain the elements necessary to eventually form stars and planets.
Sometimes referred to as a nebula
How was the solar system formed?
Over billions of years, interstellar clouds of dust gradually clump together because of its own gravity.
This eventually began to spin as a disc and eventually MOST of it ignited + became the sun.
Particles in the remaining disc of dust began to clump together + combine
–> grow into larger chunks, pulled together by gravity. –> Planets
(This is called the accretion model)
At what angle is the earth tilted
23.5 degrees
Accretion model
The conceptual model for how planets are formed from a disc of material around a star. Planets and other natural satelittes form through matter clustering together due to gravity.