Motion in the Universe Flashcards
What is the universe?
A collection of billions of galaxies
What is a galaxy?
A collection of billions of stars
What is the Milky Way?
The name of the galaxy which contains our solar system
What is a satellite?
Anything in space which travels in an orbit. Satellites can be natural such as the moon and Earth or they can be artificial such as the International Space Station
What is an asteroid?
Lumps of rock and metal that orbit the Sun
What is a comet?
Lumps of dust and ice that orbit the Sun in really long orbits
What is gravity?
Gravity is a force which prevents us from floating about on Earth and also keeps moons and planets in orbit.
What produces a gravitational field?
All objects with mass produce a gravitational field and the heavier the object the larger the gravitational field.
Why is gravity stronger on Earth than the moon?
Because the Earth has a larger mass than the moon.
How does distance affect gravitational field strength?
The closer you are to an object the stronger the gravitational field strength.
What happens to gravity as an astronaut moves away from Earth?
The force of gravity decreases.
What do gravitational forces keep in orbit?
Gravitational forces keep moons around planets planets and comets around the Sun and artificial satellites around the Earth.
What shapes do the orbits of planets and moons take?
Planets orbit stars and moons orbit planets in (almost) circular orbits.
What shape is the orbit of a comet?
Comets travel in elliptical orbits.
What happens to the orbital period as distance from the Sun increases?
The further a planet is from the Sun the longer it takes to complete one orbit.
How long does Pluto take to orbit the Sun?
Pluto takes 248 years to complete one orbit.
What happens to comets as they get close to the Sun?
As comets approach the Sun their ice vaporises forming a visible tail.
Why do comets take longer to orbit than planets and moons?
Because comets travel to the outer edges of the solar system so their orbits are much longer.
What causes a comet’s speed to increase as it gets close to the Sun?
The Sun’s gravitational pull increases the comet’s speed as it gets closer.
