Flashcards in ⭐️topic SP7 - Astronomy Deck (61)
What is the geocentric model?
The idea that the sun and all the planets are orbiting the Earth; the earth is the Center of everything
Who came up with the geocentric model?
The greeek astronomer ptolemy
What is the heliocentric model?
The idea that the sun is in the centre of the solar system
Who came up with the heliocentric model?
The polish astronomer nicolaus Copernicus
What did the invention of the telescope allow?
Scientists to see objects in space in much more detail and to find new objects
What did Galileo Galilei achieve?
The discovery of four of Jupiter’s moons and by plotting their movements he proved not everything orbited the earth and lead him to support coppernicus’s idea
What other discoveries were made with the improvements of telescopes?
Uranus, Neptune, the dwarf planet Pluto, asteroids and many comets
What is the difference between a comet and an asteroid?
Comets are mostly made of ice, asteroids are rocky bodies
What shape do all the planets move around the sun?
In an elliptical orbit
What are natural satellites?
What has the invention of photography allowed astronomers to do?
Make detailed observations and measurements.
How have computers affected modern astronomy?
Increased the speed and detail in which info from telescopes can be analysed.
Why are some telescopes in orbit around the earth?
-They give much clearer images as clouds and dust aren’t in the way.
-if the telescope is designed to detect radio waves and infrared emitted by space objects, they must be placed in orbit as the atmosphere absorbs some of that radiation
What is weight?
Mass x gravitational field strength
What is gravitational field strength in earth?
What does gravitational field strength on a body depend on?
The mass of the body and the distance from its centre to the surface (radius)
The greater the mass of a body...
...the smaller it’s radius and the greater it’s surface gravity
What are artificial satellites used for?
Communication and to observe earth and space
Describe satellites in highly elliptical orbits
The are used for communication in parts of the earth near the poles
Describe a satellite in a polar orbit
Will eventually pass over all parts of the earth
Describe satellites in circular geostationary orbits
They remain over 1 point on the Earth and are used for broadcasting. They move at 3070 m/s
Describe satellites in low earth orbits
Need the least fuel for launching and they move around 7500 m/s
Why does the force change its direction but not it’s speed on an orbiting body?
As the gravitational force between the earth and the satellite is at right angles to the direction of movement
The gravitational force of a satellite in low orbit is...
...greater than that on a satellite in higher orbit
There are two satellites. A is in a higher orbit than B, which one has to be moving faster to stay in orbit
B as if it slows down, it will fall towards the earth.
What happens when an object falls out of orbit?
It gains speed as it falls until its moving fast enough to stay in a new lower orbit, if it falls into contact with the atmosphere, then the air will slow it down and it’ll eventually fall to earth
How does a star start off?
A nebula - cloud of gas and dust
If the hydrogen in a nebula has a large enough mass?
Gravity will cause it to pull into itself to form a ball being a protostar
How is fusion triggered in starts?
When as the hydrogen atoms accelerate increasing kinetic energy and temperature allowing them to collide due to the increase in pressure