what is thought to be at the centre of the milky way
a massive black hole
The Universe is thought to have formed how many years ago
13.7 billion years ago.
The solar system formed how many years ago
4.6 billion years
what is The solar system
The solar system is any object that is bound by gravity to a Sun.
All objects in the solar system orbit The Sun.
in our solar system there is what
- one star – the Sun
- eight planets
- dwarf planets
- natural satellites called
moons that orbit planets.
Other objects in
The solar system include:
* Comets
* Asteroids
* Satellites
how does a solar system from
(a) The universe contains ‘clumps’ of
dust and gas each called a nebula.
(b) Gravitational attraction pulls this
dust and gas together.
(c) Forming the Sun (a star).
(d) Fusion reactions lead to an
equilibrium between the
gravitational collapse of the star and
the expansion of a star due to fusion
energy.
(e) The remaining parts of the solar
system form from the remaining
dust and gas.
why do small stars live longer than big stars
Small stars live a lot longer than massive stars as they use up their fuel more slowly.
The Sun will be a
main sequence
star for how long
20 billion years.
describe the life cycle of a small star
1) Nebula (Cloud of gas and dust)
2) protostar
3) Main sequence star
4) Red Giant
5) white dwarf
6) black dwarf
describe the life cycle of a large cycle
1) Nebula (Cloud of gas and dust)
2) protostar
3) Main sequence star
4) Red super Giant
5) supernova
6) neutron star / black hole
describe the Life of a star
- cloud of gas and dust (nebula)
- pulled together by gravity
- causing increasing temperature (to start fusion)
- becomes protostar
- hydrogen nuclei fuse to form helium nuclei
- fusion produce new elements
- star becomes main sequence
describe the Death of a star
- Hydrogen runs out
- helium nuclei fuse to make heavier elements
- up to iron
- star expands
- becomes red super giant
- star collapses rapidly and explodes
- called a supernova
- creating elements heavier than iron
- and distributing them throughout the universe
- leaving behind a neutron star
- or a black hole.
The Sun, releases energy though what
nuclear fusion reactions in the core.
describe how the Sun releases energy
Isotopes of Hydrogen forced together under high temperature and pressure.
Nuclear fusion occurs to form Helium and a neutron.
A tiny amount of mass is converted into a
large amount of energy, So stars emit a lot of energy.
describe Fusion
Light nuclei
Fuse to make a heavier nuclei
Some mass gets converted into energy
describe equilibrium in a star
Fusion produces thermal pressure
(pushes out)
Gravity pulls inwards
Leads to equilibrium
To avoid being pulled into the sun, a planet must be what
must be travelling faster, the closer
it is to the sun. This is why Mercury’s orbit of the sun takes 3 Earth months
whereas it takes Neptune 165 Earth years to orbit the sun.
In a perfectly circular orbit what happens
a body will travel at constant speed to maintain its
orbital distance.
why don’t things have a circular orbit
gravity is constantly changing the direction of the body. As velocity
depends on speed and direction, the velocity is constantly changing even
though speed remains the same (only direction changes)
why does red shift happen
Red shift happens because galaxys are moving away from us at high speed,
causing the wavelengths of light to be increased.
summarise what red shift is
- Red light has a longer wavelength than blue light.
- Most distant galaxies show an increase in wavelength of light.
- The further away the galaxies the faster they are moving and
the bigger the increase in wavelength. - This effect is called the RED-SHIFT.
- The observed red-shift provides evidence that the universe is expanding and supports the Big Bang theory.
how does red shift support the big bang theory
- light from galaxies shifted towards red end of spectrum
- the further away the galaxy, the greater the red shift
- wavelength (appears) to increase
- this shows that galaxies are moving away from us
- this suggests that Universe is expanding from initial point
- Cosmic Microwave Background Radiation (CMBR) can only be explained by the big bang
how do we know galaxy’s are moving away from us at different speeds
Absorption spectra from stars in every galaxy would look the same if all the
galaxies were a fixed distance from the Earth. Galaxies have different amounts of
red shift which means they are moving away from us at different speeds.
give the strengths for the Balloon model
as the balloon expands, dots get further apart, representing the galaxies moving apart
-
chemistry topic one32
-
chemistry topic 233
-
chemistry topic 318
-
chemistry topic 429
-
chemistry topic 521
-
Chemistry topic 622
-
chemistry topic 740
-
chemistry topic 828
-
chemistry topic 923
-
chemistry topic 10 (most important p2)63
-
CS 1.350
-
computer science 2.127
-
music24
-
history medicine63
-
History Germany55
-
history conflict and tension in Asia42
-
physics topic one27
-
physics topic two42
-
physics topic three12
-
physics topic four35
-
physics topic 558
-
physics topic 669
-
physics topic 747
-
physics topic 828
-
biology topic 589
-
biology topic 684
-
biology topic 764
-
elizabeth history42
-
elizabeth history 16 marker0
