Space Flashcards
1
Q
what 6 bodies make up the solar system?
A
- the sun
- planets
- moons
- dwarf planets
- asteroids
- comets
2
Q
what is our solar system a part of?
A
a galaxy
3
Q
describe the process of how stars are formed
A
- nebula- All stars begin life in the same way. A cloud of dust and gas, also known as a nebula, made mostly of hydrogen.
- protostar- Gravity begins to pull the dust and gas together. As the mass falls together it gets hot to form a protostar. hydrogen nuclei to fuse together to make helium. The fusion process releases energy, which keeps the core of the star hot
- main sequence star- the force of gravity holding the star together is balanced by higher pressure due to the high temperatures. The Sun is at this stable phase in its life.
- Following this, stars develop in different ways depending on their size.
- Stars that are a similar size to the Sun follow the left hand path:red giant star, white dwarf, black dwarf
- Stars that are far greater in mass than the Sun follow the right hand path: red super giant star, supernova, neutron star, or a black hole (depending on size)
- red giant star- When all the hydrogen has been used up in the fusion process, larger nuclei begin to form and the star may expand to become a red giant.
- white dawrf- When all the nuclear reactions are over, a small star like the Sun may begin to contract under the pull of gravity. It fades and changes colour as it cools.
- supernova- A larger star with more mass will go on making nuclear reactions, getting hotter and expanding until it explodes as a supernova, throwing hot gas into space
- black hole- Depending on the mass at the start of its life, a supernova will leave behind either a neutron star or a black hole.
4
Q
how do fusion processes lead to the formation of new elements?
A
- In a main sequence star, hydrogen nuclei fuse together to form helium nuclei.
- This happens in several steps, but one way to simplify the overall change is:
- Two hydrogen nuclei fuse to produce a helium nucleus and a neutron.
5
Q
how have supernovas allowed heavy elements to appear in later solar systems?
A
- Elements heavier than iron are formed in the supernova explosions of high mass stars.
- When the supernova explodes, all the elements produced are thrown out into the Universe.
- The heavy elements found on Earth, such as gold, came from material thrown out in previous supernova explosions.
6
Q
what happens to velocity and speed in a circular orbit?
A
- the force of gravity leads to a constantly changing velocity but unchanged speed
- change in velocity results in
acceleration, so an object moving in a circle is accelerating even though its speed may be constant. - An object will only accelerate if a
resultant force acts on it. For an object moving in a circle, this resultant force is the centripetal force that acts towards the middle of the circle. - Gravitational attraction provides the centripetal force needed to keep planets and all types of satellite in orbit.
7
Q
explain the relationship between radius and speed in a stable orbit
A
- the radius must change if the speed changes
- The gravitational attraction between two objects decreases with distance.
- This means that the closer the two objects are to each other, the stronger the force of gravity between them.
- If the force between them is greater, a greater acceleration will occur.
- The greater the acceleration, the greater the change in velocity - this causes the object to move faster.
- This means that objects in small orbits travel faster than objects in large orbits.
8
Q
define red-shift and explain how it happens
A
- The change in wavelength of light from a distant star moving away from Earth.
- Astronomers can observe light from distant galaxies.
- When they do this, they see it is different to the light from the Sun.
- The dark lines in the spectra from distant galaxies show an increase in wavelength.
- The lines are moved or shifted towards the red end of the spectrum.
9
Q
how does red-shift change with distance from the earth and what is this a result of?
A
- The more red-shifted the light from a galaxy is, the faster the galaxy is moving away from Earth.
- Astronomers see red-shift in virtually all galaxies.
- It is a result of the space between the Earth and the galaxies expanding.
- This expansion has the effect of increasing the wavelength of the light from these galaxies, shifting them towards the red end of the spectrum.
10
Q
why is the change of each galaxy’s speed with distance evidence of an expanding universe?
A
- the wavelength of light from most distant galaxies is increased
- they are longer than they should be- they’re towards the red end of the spectrum (red-shift)
- measurements of red-shift suggests the source of light (such as distant galaxies) is moving away from us
- more distant galaxies have greater red-shifts than nearer ones meaning they are moving away faster than the nearer ones
- this means all galaxies are moving away from every other galaxy- the whole universe is expanding
11
Q
how did scientists use observations to arrive at the big bang theory?
A
- red-shift= Universe was a very small, extremely hot and dense region. From this tiny point, the whole Universe expanded outwards to what exists today.
- More distant galaxies have greater red-shift= More distant galaxies should move away faster
- CMBR (cosmic microwave background radiation) is everywhere at a temperature of about -270°C= Initial Big Bang heat should now be thinly spread across the whole Universe
12
Q
give 2 examples of things in the universe that are still not understood
A
- The expansion of the Universe appears to be accelerating. Scientists do not entirely understand how this could happen but call it dark energy- An unknown form of energy, put forward as a solution to the problem of why the expansion of the Universe is accelerating.
- dark matter- An unidentified form of matter that accounts for galaxies rotating faster than their visible mass should cause. galaxies seem to rotate too quickly for the mass of their stars. This suggests that there is mass in the Universe that is invisible to the instruments used by scientists
