2.5 - Stars and planets Flashcards

1
Q

In which galaxy is our solar system?

A

The Milky Way galaxy

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2
Q

What does our solar system consists of?

A

Four inner rocky planets and four outer gas giant planets as well as an asteroid belt, containing thousands of huge rocks, dwarf planets and comets.

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3
Q

What do the planets in our solar system orbit around and what type of body is it?

A

The planets orbit around the sun

The sun is a star

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4
Q

What type of force pulled together the cloud of dust and gas to form the sun?

A

Gravitational force of attraction

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5
Q

What is the order of the planets in our solar system?

A
My            - Mercury
Very         - Venus 
Easy         - Earth
Method    - Mars 
Just           - Jupiter
Speeds     - Saturn 
Up             - Uranus 
Naming    - Neptune
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6
Q

The planets go around the Sun in slightly squashed circular elliptical orbits. What is an elliptical orbit?

A

An orbit that is the shape of an ellipse. An ellipse is similar to a slightly stretched circle

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7
Q

What are comets?

A

A high speed ball of ice and rock which as it melts leaves a trial of dust and gas behind it

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8
Q

What are asteroids?

A

Lumps of rock which orbit the sun in the asteroid belt

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9
Q

How does a solar system form?

A dense hydrogen-rich cloud of ___ and ___ contracts under gravity. As the gas gets compressed, its temperature ________ and the dust cloud begins to spin. A ______ begins to form at the centre of this spinning dust cloud. _____ _____ starts, and a star is born. The planets begin to form from the swirling dust clouds around the star.

A

gas and dust
increases
protostar
nuclear fusion

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10
Q

What word is used to describe a cloud of dust and gas?

A

A nebula

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11
Q

What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together

A

Fusion reactions

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12
Q

Gravity is greater closer to the star. Most of the dense material in the dust cloud is attracted strongly and ends up here. The left over ____ (dust/ gas) created rocky planets near the sun and the left over ____ (dust/ gas) created gas giants further away from the sun

A

Dust

Gas

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13
Q

What is a light year?

A

The distance light travels in one year

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14
Q

What is an astronomical unit (AU)?

A

The mean distance from the Earth to the Sun

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15
Q

What unit of measurement is used to measure distances between the sun and planets ?

A

The Astronomical Unit (AU)

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16
Q

Alpha Centauri is 4.4 light years away from us. Can you work out this distance in metres?

A

4.4 ly × 9.46 × 10^15 m / ly

= 4.16 × 10^16 m

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17
Q

What colour stars are the hottest? Blue or red?

A

Blue stars are the hottest stars

Red stars are the cooler stars

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18
Q

Put these things into order from smallest to biggest:

Milky Way
Earth
Solar system 
Universe
Sun
A

1) Earth
2) Sun
3) Solar System
4) Milky Way
5) Universe

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19
Q

What factor determines the type of lifecycle a star undergoes?

A

The size (and therefore mass) of the star

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20
Q

What two stages do all stars of the same or greater size than the sun undergo?

A
  1. Protostar phase

2. Main sequence phase

21
Q

What do stars like the sun become at the end of their life-cycle?

A

A black dwarf

22
Q

What two things can stars much bigger than our sun become at the end of their lifecycle?

A
  1. Neutron star

2. Black hole

23
Q

What two phases do stars like the sun experience between being a main sequence star and a black dwarf

A
  1. Red giant

2. White dwarf

24
Q

What two phases do stars of greater size than our sun go through between being a main sequence star and a neutron star/ black hole?

A
  1. Red supergiant

2. Supernova

25
Q

What condition is required for fusion reactions to occur in a star?

A

Very high temperatures and pressures

26
Q

Where are elements heavier than iron produced?

A

In a supernova

27
Q

What type of nuclei fuse together to form heavier elements in a star?

A

Hydrogen nuclei fuse to form heavier elements

28
Q

How are elements distributed throughout the universe?

A

Through the explosion of a massive star (supernova)

29
Q

What allows planets and satellites to maintain circular orbits?

A

Gravity provides the gravitational force that acts as the object’s centripetal force (a force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving)
The presence of a centripetal force allows for the object to maintain its circular orbit

30
Q

What type of satellite can a planet’s moon be described as?

A

A natural satellite

31
Q

What type of planet is Pluto classed as?

A

A dwarf planet

32
Q

What is the name given to the natural satellites that orbit planets?

A

Moons

33
Q

What term is given to the 4 outer planets of our solar system?

A

Gas giants

34
Q

What is the order of stages in the life cycle in a high mass star?

A

1) Protostar
2) Main sequence star
3) Red supergiant star
4) Supernova
5) Neutron star (If star not one of biggest)
6) Black hole ( If star is one of biggest)

35
Q

What is the order of stages in the life cycle in a low mass star?

A

1) Protostar
2) Main sequence star
3) Red giant star
4) White dwarf
5) Black dwarf

36
Q

What is a protostar?

A

A cloud of gas and dust collapses due to gravity to form a baby star known as a protostar

37
Q

What is a Main Sequence Star?

A

When the protostar is hot enough to fuse hydrogen into helium it becomes a main sequence star

38
Q

What is a red giant?

A

Once all the hydrogen has run out the star expands into a red giant where it can fuse heavier elements together up to iron

39
Q

What is a White Dwarf?

A

When the star can’t fuse anything together it sheds its outer layers and collapses into a small dense white dwarf. Overtime this will cool down and get dimmer.

40
Q

What is a red super giant?

A

If the star is much bigger than the sun it will become a red super giant when it runs out of hydrogen

41
Q

What is a supernova?

A

A supernova is a huge explosion of the star which is where all the elements heavier than iron are formed

42
Q

What is a black hole?

A

If the star is one of the biggest in the universe once it has exploded in a supernova it will become a black hole. These have gravity so strong that nothing can escape them (not even light)

43
Q

What is a neutron star?

A

If the star is not one of the biggest stars, after it has exploded in a supernova it will become a neutron star which is very dense and filled with neutrons

44
Q
Where can you fine these elements?
Hydrogen
Helium
Elements bigger than helium (up to Iron)
Elements bigger than iron
A

Hydrogen - The Big Bang
Helium - main sequence stars
Elements bigger than helium (up to Iron) - red giant/ red super giant stars
Elements bigger than iron - supernova

45
Q

What are the two forces acting on a star?

A

Gravity (inwards)

Gas and radiation pressure (outwards)

46
Q

In which stage of a stars life is the forces of gravity and gas and radiation pressure equal? Hence meaning the star is stable.

A

Main sequence star

47
Q

When the star runs out of hydrogen there is no more fusion. This means pressure ______ (increases/ decreases). Gravity is bigger than pressure so the star _____. This causes it to get hotter and more dense. This extra heat means fusion can kick start again and the star can start to fuse helium. This means pressure ______ (increases/decreases). Pressure is now bigger than gravity so the star expands and cools down.

This continues throughout the star’s life time as a red super giant. This causes layers to be created with lighter elements on the outside and heavy elements in the centre.

A

decreases
shrinks
increases

48
Q

What does the Hertzsprung-Russell Diagram show?

A

The luminosity of stars against there temperature