Space Physics Flashcards

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1
Q

describe the formation of stars

A

nebula ( cloud of gas and dust). Gravity causes this to spiral together to form a protostar. gravity causes the density to increase and particles collide more frequency so temperature rises.

when it gets hot enough, hydrogen nuclei begin to undergo nuclear fusion to form helium nuclei

at this point a star is born

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2
Q

explain what happens through the life of a main sequence star

A

energy released by nuclear fusion gives outward force, balanced by the force of gravity pulling inwards. equilibrium. its like this for several billion years. when hydrogen runs out fusion of heavier elements occurs up to iron in the core occurs .

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3
Q

what happens to a star about the same size as the sun when it dies

A

expand into a red giant when it begins to run out of hydrogen. becomes red because the surface cools.

it will then become unstable and eject its outer layer of gas and dust as a planetary nebula.

this leaves behind a hot dense solid core (white dwarf)

when it no longer emits a significant amount of energy it is a black dwarf and eventually disappears from sight

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4
Q

what happens when a star much bigger than the sun dies

A

explode into red super giants when they run out of hydrogen. they explode and contract several times forming elements as heavy as iron in nuclear reactions.

eventually they run out of elements to fuse and become unstable and explode in a supernova, forming elements heavier than iron.

this leaves a dense core called a neutron star. If the neutron star is big enough, it will become a black hole.

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5
Q

what are 3 things the sun is orbited by

A

planets
dwarf planets
satellites

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6
Q

what are satellites

A

objects that orbit a second more massive object. for example moons and artificial satellites

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7
Q

explain how a planet stays in orbit

A

the planet is accelerating towards the sun because the force of gravity is pulling to the sun. However the motion of the object (instantaneous velocity) is pulling it a a right angle to the force

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8
Q

how does speed of an object effect the radius of an objects orbit

A

if the object moves faster the radius must be smaller

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9
Q

what is red shift

A

when you looks at light from a distance the wavelength increases, causing it to move to the red end of the spectrum

it occurs when the source of the light is moving away from the observer

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10
Q

how do we know the universe is expanding

A

the light from over galaxys has been red shifted suggesting it is moving away from us. More distant galaxys have a greater red shift than nearer ones suggesting they are moving away quicker

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11
Q

what is the big bang theory

A

all matter was occupied in a very tiny, hot, dense space.

then it exploded and started expanding, and is still expanding now

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12
Q

what are 3 unexplained things about the universe

A

galaxies are accelerating away at faster and faster speeds but dont know why

dark matter is an unknow substance which holds galaxies together

dark energy is thought to be responsible for the accelerated expansion of the universe

no one knows what these things are

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