5.) Topic 5 Stars And Planets Flashcards
In which galaxy is our solar system
The Milky Way Galaxy
How many planets make up our solar system?
8 (plus the dwarf planets)
What do the planets in our solar system orbit around and what type of body is it?
Orbit around the sun
The sun is a star
What type of force pulled together the cloud of dust and gas to form the Sun?
Gravity (Gravitational force of attraction)
Name all the planets in our solar system in order
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
What type of planet is Pluto
Pluto is a dwarf planet
What type of planets are Mercury, Venus, earth and mars?
Rocky planets
What type of planets Jupiter, Saturn, Urnaus, Neptune and Pluto
Gas planets
Where is the asteroid belt located?
In between Mars and Jupiter
What are asteroids?
Asteroids are lumps of rock which are in orbit of the sun
Give an example of a dwarf planet in the asteroid belt and what is its diameter?
Ceres - diameter of 587 miles
What are comets?
Comets are lumps of ice and dust which are in highly elliptical orbit of the sun
Give an example of a comet and what’s the orbital period of it
Halley’s comet - orbital period of about 75 years
What word is used to describe a cloud of dust and gas?
A nebula
What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?
Fusion
What factor determines the type of lifecycle a star undergoes?
The size (and therefore mass) of a star
What is another word given to moons?
Natural satellites
What is AU
What does 1 AU equal
The mean distance from the centre of the earth to the centre of the sun
1AU = 1.496 x 10 (power of 11) metres
What is a light year
What does 1 light year equal
Light year is the distance light travels in a year
1 Light year = 9.46 x 10 (power of 15) metres
What does SM stand for
Solar masses
Which 2 planets have no moons
Mercury and venus
How does a solar system form? [4]
A dense hydrogen-rich cloud of gas and dust contracts under gravity. As the gas gets compressed, its temperature increases and the dust cloud begins to spin. A protostar begins to form at the centre of this spinning dust cloud. Nuclear fusion starts, and a star is born. The planets begin to form from the swirling dust clouds around the star.
What do stars produce by nuclear fusion?
Energy
What colour are hot, bright stars
Blue
What colour are very small, colder or old dying stars?
Red
What makes a star stable
When fusion energy and gravity are equal
Describe the life cycle of a star for smaller stars like our sun
Stars begin their life cycle as a cloud of dust and gas called a nebula
Gravity causes the cloud of dust and gas to collapse
As the particles move faster, the temperature rises to millions of degrees celcius. This early stage is called a proto-star.
Eventually the pressure gets so great that the particles fuse together. This is nuclear fusion when hydrogen nuclei fuse together to form helium nuclei
In a main sequence star, at some stage the hydrogen in the star will start to run out.
At this point the outward force due to fusion energy is less than the inward force due to gravity. This causes the star to collapse inwards. The collapse cause its temperature to increase. Now helium nuclei fuse together to form heavier elements up to Iron.
This forms a red giant which expels its outer layers and stops using helium. This is a plenary nebula.
The star than shrinks and forms a white dwarf. After a while, the white dwarf becomes cooler and forms a black dwarf.
Describe the life cycle of a star for bigger stars
Once bigger stars run out of hydrogen, they leave the main sequence stage and expand to form red super giants.
Helium nuclei fuse together to form heavier elements. At some point, the red super giants stops carrying out nuclear fusion and explodes. This is called a supernova.
The temp of a supernova is high enough to form elements heavier than iron. These elements are ejected across the universe. If the star mass was greater than 25, it forms a black hole. It has such a large gravity that not even light can escape. If it mass less than 25, it forms a neutron star
Describe life cycle of star (summary)
Nebula - protostar - main sequence star (smaller like sun)- red giant - plenetary nebula - white dwarf - black dwarf
Nebula - protostar - main sequence star (bigger stars) - red super giant- supernova - either black hole or neutron star
Which 2 phases do stars like our sun experience between being a main sequence star and a black dwarf
Red giant
White dwarf
Which 2 phases do bigger stars experience between being a main sequence star and a neutron star/black hole
Red super giant
Supernova
What condition is required or fusion reactions to occur in star
Very high temps and pressures
Where are elements heavier than iron produced
Supernova
What type of nuclei fuse together to form heavier elements in a star?
Hydrogen nuclei fuse to form heavier elements
What allows planets and satellites to maintain circular orbits? x2
Gravity
Presence of a centripetal force
Give 2 examples of artificial satellites
TV satellites
Satellites used for satellite imaging
What does a Hertzsprung - Russell diagram show?
The luminosity of stars against their temperature
What are brown dwarfs
Failed stars that don’t have enough mass in order to get hot enough to achieve nuclear fusion
What are red dwarfs
Low mass stars that do achieve nuclear fusion. They are not very bright and have very long life times. They are main sequence stars
At the end of a main sequence stage of our sun, what happens? (7)
. Light elements fuse in the centre
. Centre is exhausted of light elements - nuclear reactions top, causing pressure to drop
. Star nucleus shrinks, making density and temp to go up, allowing heavier elements to fuse
. Meanwhile the lighter elements continue fusing in a shell around the nucleus
. Stars like our sun never reach sufficient temps to fuse elements heavier than oxygen
. The outer layers of the star are pushed off by the radiation pressure of the core - enriching the interstellar medium with heavier elements
. A very dense core remains known as a white dwarf
How is a new star born (6)
Material from supernova mixes up with interstellar dust and gas. Shockwave from supernova and kickstart collapse of nebula. The effect then is the dust and gas in a nebula contracts over time. As nebula contracts, gravitational collapse converts gravitational potential energy into kinetic energy. Eventually temps of nebula reach high temps and density for fusion to start - star is born.
During formation rock tended to gather closer to the Sun and formed rocky planets whilst gaseous substances gathered together at distances further from sun to form gas planets
