Topic 3- Astronomy Flashcards Preview

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Flashcards in Topic 3- Astronomy Deck (38):
1

The solar system contains...

Planets
Dwarf Planets
Moons
Artificial satellites
Asteroids
Comets

2

Planets...

Large objects that orbit a star

3

Dwarf planets...

These are planet-like objects that aren’t big enough to be planets
Eg. Pluto

4

Moons...

These orbit planets with almost circular orbits
They are a type of natural satellite (not man made)

5

Artificial satellites...

Ones humans have built that usually orbit the Earth in a fairly circular orbits

6

Asteroids...

Lumps of rock and metals that orbit the Sun
Usually found in the asteroid belt

7

Comets...

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

8

Planets in our solar systems...

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
(Pluto)

9

Objects in a circular orbit at a constant speed is...

Constantly accelerating

10

The force which causes circular orbit is...

Centripetal force
It acts towards the centre of the circle

11

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

12

The object keeps accelerating towards what its orbiting but the ... (which is at a right angle to the acceleration)...

Instantaneous velocity
Which keeps it travelling in a circle

13

The force that makes the orbit travel in a circle is provided by...

Gravitational force between the planet and the Sun

14

Gravitational field strength depends on...
The larger the...

Body creating the field
Mass of the body, the stronger it’s gravitational field

15

Gravitational field also varies with...

With distance
The closer you get to a star or planet, the stronger the gravitational force is

16

The ... the force, the ... the instantaneous velocity needed to ... it

Therefore the closer to a star or planet you get, the...

Stronger/Larger/Balance

The faster you need to go to remain in orbit

17

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

18

Geocentric model...

The Sun, moon and planets and stars all orbit Earth is perfect circles
Accepted model during the Ancient Greeks times until 1500s

19

Heliocentric model...

Earth and all of the planets orbited the Sun in perfect circles
Galileo evidence- Jupiter’s moons

20

The modern model...

Planets orbit the Sun
But in elliptical orbits

21

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

22

The Big Bang theory...

The tiny space was very dense and very hot
Explosion - the space starts expanding and still does
Finite age
Currently the accepted theory

23

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

24

Lifecycle of a star...

Nebula,
Prostar,
Main sequence star,
Red supergiant (/Red giant)
Supernova (/White dwarf)
Neutron star or black hole

25

Nebula...

Cloud of dust and gas

26

Prostar

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

27

Main sequence star

Long stable period
Outward pressure of thermal expansion balances the force of gravity pulling everything inwards
Lasts billions of years

28

Red giant/supergiants

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

29

White dwarf

Small- medium star ejects it’s outer layer of dust and gas
Leaving behind a hot, dense solid core

30

Supernovas

Start to undergo fusion again
Expand and contract serval times as the balance shifts between gravity and thermal expansion
Explode in a supernova

31

Neutron star

A very dense core left from the exploding supernova when the outer layers of gas and dust are thrown into space

32

Black hole

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

33

How to improve the quality of an image on a telescope

Increase the aperture
Use a higher quality objective lens

34

What can effect the image from a telescope

The atmosphere (absorbs light)
Pollution - light and air pollution from the cities

35

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)

36

X rays telescopes

Can see violent, high temperature events in space, like exploding stars

37

Radio telescopes

Responsible for the discovery of the cosmic microwave radiation, learnt more about origin of the Universe

38

Modern telescope

Better resolution
Gather more light
Improved magnification
Work alongside computers