6.12 Astronomy - Universe, Galaxies, Solar System etc. Flashcards
What are planets?
These are large objects that orbit a star. They also have to be large enough to have “cleared their neighbourhoods”. This means that their gravity is strong enough to have pulled in any nearby objects apart from their satellites. All the plants in the solar system orbit the Sun in the same direction.
What are minor planets?
These include comets and asteroids, like Halley’s comet. These are objects that orbit stars, but don’t meet all of the rules for being a planet.
What are artificial satellites?
Satellites that humans have built. They generally orbit the Earth. A satellite is just an object that orbits a second, more massive object.
What are moons?
These orbit planets. Most planets in the solar system have at least one. They’re a type of natural satellite.
What is our solar system apart of?
The Milky Way Galaxy
What is the Milky Way Galaxy?
This is a massive collection of billions of stars that are all held together by gravity.
For an object in orbit, the _________ its speed, or the ________ the orbital radius, the greater the force needed to keep it in a stable orbit. A stable orbit just means the object is orbiting with a constant speed.
greater, smaller
How was the solar system formed? (7)
- Our solar system was formed from one big swirling cloud of dust and gas.
- All parts of the dust and gas attracted all other parts due to gravity, so over a long period of time, the force of gravity brought the gas and dust together.
- As the dust and gas collapsed towards the centre of the cloud, the density of the cloud increased, particularly at the centre.
- Areas of higher density had a greater gravitational pull, so they got denser and denser.
- The force of gravity did work to compress the dust and gas in this way. In terms of the particle model, energy was transferred to the kinetic energy stores of the particles, increasing the temperature and pressure, so the denser regions also got hotter and hotter.
- The region at the very centre of the cloud became so dense and hot that it eventually formed the Sun.
- Other areas of high density further out also got denser and hotter. Eventually, the dust and gas was compressed together enough to form planets. They orbit the Sun as any leftover bits of the cloud continue to swirl, and the Sun’s gravity holds them all in place.
What type of orbit do the planets orbit the sun around?
An elliptical orbit
What is an elliptical orbit?
An orbit that isn’t a perfect circle
What is any star being orbited by planets called?
A star system
What is the asteroid belt?
A region of our solar system that contains millions of asteroids
Which two planets is the asteroid belt found between?
Mars and Jupiter
What is a comet mostly made of?
Ice and dust
What is an asteroid mostly made of?
Rock and metal
