Physics - Space & Beyond Flashcards
What are some ideas about the universe from different cultures?
Some poeple thought the Sun was eaten by monsters during a solar eclipse.
People thought the earth was flat and was supported by pillars surrounded by oceans.
The earth was supported on the back of a turtle.
Describe the geocentric model of the solar system.
In this model the Sun, Moon, planets, and stars moved around the Earth.
They moved on crystal spheres that light could travel through.
Suggest an observation that could not be explained by the geocentric model.
Sometimes the planets appeared to go backwards. This is called retrograde motion. You do not notice it during one night, but if you make observations over several months you can see that the paths of the planets change direction. However this model stated that they all move in perfect circles.
How did observations lead to a different model of the Solar System?
To explain all of the problems with the geocentric model, Copernicus suggested that the earth and all of the planets orbited the Sun.
What are some similarities and differences between different models of the Solar System?
Similarities:
* Both rotate around one celestial body
* Both used to try to show what orbits what in the universe
* both models of the solar system
* the moon orbit the earth in both
Differences:
* Geocentric-everything revolves around the earth
* heliocentric - everything revolves around the sun
* the heliocentric model were ellipses not circular orbits
Describe the heliocentric model of the Solar System.
In this model the planets orbited the Sun.
Describe the timescale of the Universe.
The Big Bang happened 13.8 billion years ago
The first stars appeared 150 million years after the Big Bang
The milky way formed 13.6 billion years ago
The sun formed 4.6 billion years ago
The earth formed 4.6 billion years ago
The first life appeared on earth 3.7 billion years ago
Dinosaurs lived between 200 million years ago and 65 million years ago.
Humans have existed for less than half a million years.
Why could atoms not be formed immediately after the Big Bang?
The universe was both too hot and too dense for elements to form. Hydrogen didn’t appear until the universe had spread out — and subsequently cooled — enough for the first protons and neutrons, and later simple atoms, to form
What is meant by the Big Bang?
The expansion of space which scientists believe is how the Universe started.
How is the Big Bang theory supported by evidence?
Red shift (wavelength of the light is stretched, so the light is seen as ‘shifted’ towards the red part of the spectrum meaning the source is further away) shows that stars and galaxies are moving away from each other which shows that the universe is expanding.
How do you get a satellite into orbit?
A satellite maintains its orbit by balancing two factors: its velocity (the speed it takes to travel in a straight line) and the gravitational pull that Earth has on it.
Compare the orbits of different satellites.
Geostationary orbit:
Passes over the equator.
Takes 24 hours to complete one orbit
It stays above the same point on the Earth all the time
Low polar orbit:
Passes over the poles
Takes less than a day to complete one orbit
It doesn’t stay above the same point on the earth all the time.
Low earth orbit:
Passes over anywhere
Takes less than a day to complete one orbit.
It doesn’t stay above the same point on the earth all the time.
What are some uses of satellites?
Satellites are used for
* communication
* monitoring the weather
* studying the Earth and space
What are some risks of the space programme?
The rocket exploding with the astronauts lying on top.
As they travel back to Earth through the atmosphere the spacecraft could get very, very very hot due to friction.
Their parachutes might not work to slow their descent.
There is danger from the Sun while they were travelling there and back. The Sun produces lots of radiation. Occasionally the Sun emits a solar flare. A huge amount of extra radiation is thrown out into space. A solar flare could stop all the on-board computers working.
Space debris could collide with a spacecraft.
The rockets launched pollute the atmosphere.
Lots of money is spent on the missions rather than more important things.
What are some benefits of the space programme?
The liquid-cooled suits used by racing-car drivers and fire-fighters are based on the Apollo astronauts’ spacesuits.
The computer programs for swiping credit cards use software designed for the Apollo missions.
Water filters use technology designed to recycle astronauts’ urine.
Baby-milk formulas are based on protein-rich drinks developed for astronauts.
The shock-absorbing materials used in sports shoes were developed for spacesuits.
