Flashcards in Topic 3- Astronomy Deck (38):
The solar system contains...
Large objects that orbit a star
These are planet-like objects that aren’t big enough to be planets
These orbit planets with almost circular orbits
They are a type of natural satellite (not man made)
Ones humans have built that usually orbit the Earth in a fairly circular orbits
Lumps of rock and metals that orbit the Sun
Usually found in the asteroid belt
Lumps of ice and dust that orbit the Sun
Orbit usually highly elliptical- a very stretched out circle
Some travel from near the Sun to the outskirts of our Solar system
Planets in our solar systems...
Objects in a circular orbit at a constant speed is...
The force which causes circular orbit is...
It acts towards the centre of the circle
The centripetal force cause the object...
To just fall towards whatever it’s orbiting
But as the object is already moving, it causes it to change direction
The object keeps accelerating towards what its orbiting but the ... (which is at a right angle to the acceleration)...
Which keeps it travelling in a circle
The force that makes the orbit travel in a circle is provided by...
Gravitational force between the planet and the Sun
Gravitational field strength depends on...
The larger the...
Body creating the field
Mass of the body, the stronger it’s gravitational field
Gravitational field also varies with...
The closer you get to a star or planet, the stronger the gravitational force is
The ... the force, the ... the instantaneous velocity needed to ... it
Therefore the closer to a star or planet you get, the...
The faster you need to go to remain in orbit
For an object in a stable orbit, if the speed of the object changes , the size of the its orbit...
Faster moving objects will move in a stable orbit with...
Must do too
A smaller radius than slower moving ones
The Sun, moon and planets and stars all orbit Earth is perfect circles
Accepted model during the Ancient Greeks times until 1500s
Earth and all of the planets orbited the Sun in perfect circles
Galileo evidence- Jupiter’s moons
The modern model...
Planets orbit the Sun
But in elliptical orbits
Steady state theory...
No beginning or end (has existed and always will)
As the universe expands, new matter is constantly being created
This means that the density of the universe is always roughly the same
The Big Bang theory...
The tiny space was very dense and very hot
Explosion - the space starts expanding and still does
Currently the accepted theory
Evidence for the Big Bang theory
Red shift- wavelengths and frequency of the light spectrum change and move more towards the red
Cosmic Microwave Background Radiation- remains of the energy created from the Big Bang theory
Expanding- this supports the theory of a single explosion
Lifecycle of a star...
Main sequence star,
Red supergiant (/Red giant)
Supernova (/White dwarf)
Neutron star or black hole
Cloud of dust and gas
Force of gravity pulls dust and gas together
Temperature rises as the star gets denser
More particles collide with each other
Hydrogen nucleus can undergo nuclear fusion to form a helium nuclei
Lots of energy = hot
Main sequence star
Long stable period
Outward pressure of thermal expansion balances the force of gravity pulling everything inwards
Lasts billions of years
The hydrogen in the core runs out
Gravity force is larger than pressure, compressing the star until it is hot and dense enough to make the outer layers expand
Becomes red because the surface cools
Red giant- small star
Red supergiant- larger star
Small- medium star ejects it’s outer layer of dust and gas
Leaving behind a hot, dense solid core
Start to undergo fusion again
Expand and contract serval times as the balance shifts between gravity and thermal expansion
Explode in a supernova
A very dense core left from the exploding supernova when the outer layers of gas and dust are thrown into space
If the star is big enough it will collapse
Forming a black hole, a very very very dense point in space
Light can’t escape from it
How to improve the quality of an image on a telescope
Increase the aperture
Use a higher quality objective lens
What can effect the image from a telescope
The atmosphere (absorbs light)
Pollution - light and air pollution from the cities
Best view for a telescope
On top of a mountain because...
-Less atmosphere above it
-In a dark place away from cities
(Or in space to avoid the atmosphere all together)
X rays telescopes
Can see violent, high temperature events in space, like exploding stars
Responsible for the discovery of the cosmic microwave radiation, learnt more about origin of the Universe