topic 7

Created by

Bethan Newman

Cards (36)

What is in the solar system?
planets, dwarf planets, moons, artificial satellites, asteroids and comets
What is an asteroid? 
A rock orbiting the Sun that was left over when the planets formed.
usually found in the asteroid belt
What is a comet? 
an object made of gas, ice, and dust that orbits around the sun
usually have a highly eliptical orbit
What is the geocentric model?
Earth is the center of the solar system
it was accepted at the times of the ancient greeks
what is the heliocentric model?
The sun is the center of the solar system
How did Galileo's discoveries help support the heliocentric theory?
While looking at Jupiter with a telescope, he noticed some stars in a line near a planet
he saw these "stars" never moved away from the Jupiter and seemed to be carried along with the planet
This showed not everything orbitted the earth
How do orbits work?
There is an attracting force between any two objects, and it pulls them together, and the gravitational force makes one orbit the other
The centripetal force always pulls the object towards the centre of the object it is orbitting
Because the object is always changing direction (and velocity is a vector), it can be said to be accelerating, as its velocity is changing, even is its speed isn't.
What are the stages of the lifecycle of a sun-sized star?
nebula
protostar
main sequence star
red giant
white dwarf
What are the stages of the lifecycle of a large star?
nebula
protostar
main sequence star
red supergiant
supernova
neutron star or black hole
What is a nebula?
a cloud of gas and dust
Describe a protostar 
The force of gravity pull the gas and dust in a nebula together to form a protostar
The temp rises as the protostar gets denser, and when it gets high enough, hydrogen nuclei undergo nuclear fusion to become helium nuclei
This gives out lots of energy which keeps the core hot
Describe main sequence stars
During this stable phase in the life of a star, the force of gravity holding the star together is balanced by higher pressure due to the high temperatures. The Sun is at this stable phase in its life, which usually lasts several billion years.
The heavier the star, the shorter the main sequence period
Descibe a red giant
The hydrogen in the core begins to run out and the force due to gravity is greater than the pressure of thermal expansion. The core is compressed, until it is dense and hot enough that the enrgy released makes the outer layers expand. The star becomes a red giant, or a red super giant. It becomes red and the surface cools.
Describe a white dwarf 
A small-to-medium-sized star like the sun then becomes unstable and ejects its outer layers, leaving behind a dense, solid core - a white dwarf
Describe a supernova 
Big stars glow brightly again (after being a red super giant) and undergo more fusion to produce heavier elements. They expand and contract several times as the balance shifts between thermal expansion and the force due to gravity. Eventually, they explode in a supernova.
Describe a neutron star
The exploding supernova throws the outer layers of dust and gas into space, leaving a very dense core - a neutron star
Describe a black hole
If the star is massive enough, the supernova will collapse and become a black hole - a super dense region of space from which light cannot even escape.
What is the doppler effect?
A change in sound frequency caused by motion of the sound source, motion of the listener, or both.
When an object moves forwards, the wavelengths in front are much shorter than thsoe behind it. This means the frequency observed in front will be much higher.
Therefore, when the object is travelling away from you, the observed frequecy will be much lower.
What is red shift? 
When the wavelengths from distant galaxies shift towards the red end of the spectrum in order to be longer than they should be
An increase in wavelength
This indicates they are moving away from us, and each other, indicating the universe is expanding
How does red shift provide evidence for the Big Bang
it suggests the universe is expanding.
What is the Big Bang Theory?
the idea that all matter and energy in the universe began in an unimaginably dense state, and then space itself began expanding
it gives the universe a finite age
What is the evidence for the Big Bang Theory?
CMBR and red-shift.
What is CMBR and how does it support the Big Bang theory?
Cosmic Microwave Background Radiation
It is coming from all parts of the universe, and shows that the universe was originally much hotter and denser, suggesting that the universe had a beginning.
What is the evidence for the Steady State Theory? 
Red shift
Why do space telescopes obtain clearer images than Earth-based telescopes?
There is less light and air pollution, so it is easier to pick out dim objects
What are X-ray telescopes used for?
To see violent high temperature events, like stars exploding
What are radio telescopes used for?
cosmic background radiation
how have telescopes improved
better resolution, better magnification, often work with computers which can create clearer images or store and analyse huge amounts of data
what is a geostationary orbit?
When an object orbits at the same spot in relation to the earth. If an object is far enough away it will orbit at the same speed as the earth spins. this means that it will make a complete orbit once every 24 hours
what is the steady state theory?
constant density
matter is always added
no beginning or end
universe expands
what is big bang theory?
started 14 billion years ago
began from small hot dense spot
universe expands
what evidence supports both theories?
red shift
what is red shift?
galaxies moving away from each other
wavelength increases and frequency decreases
what is cmbr? 
cosmic microwave background radiation
leftover radiation from the big bang
what theory is cmbr evidence for?
big bang
how does red shift provide evidence for universe expanding?
galaxies are moving further away