P8.3.1-2 Flashcards
What do we use as evidence to say that galaxies are moving away?
Red shift
What is red shift?
- Our universe is expanding, as an galaxy moves further away in space, the wavelength increases and frequency decreases.
- Since the wavelength is longer, the light coming from the galaxies is shifted towards the red end of the spectrum, giving off a red light.
If a galaxy is moving away from us and its distance is increasing, is it going faster or slower?
Faster
How did our universe start?
With the big bang
- All matter occupied a single point
- Exploded
- Space started expanding and is still expanding.
What other evidence is there for the big bang?
- Microwave radiation is coming form all direction
- This is leftover from the Big Bang
- Called Cosmic Microwave Background Radiation (CMBR)
- This energy has stretched overtime to be equivalent to the microwave region of the electromagnetic spectrum.
What does our solar system comprise of?
Sun Planets Moons (natural satellites) Minor Planets (e.g. dwarf planets like Pluto, asteroids) Comets Artificial satellites
What are the 4 inner planets?
Mercury, Venus, Earth and Mars
What are the atmospheres on Venus, Mars and Mercury like?
On Mars and Mercury the atmosphere is thin.
On Venus the atmosphere is made of mainly CO2 and it rains sulphuric acid.
What are the 4 outer planets?
Jupiter, Saturn, Uranus and Neptune
What are Jupiter and Saturn known as?
The gas giants
What are Uranus and Neptune known as?
The ice giants
What is the asteroid belt?
- It is between Mars and Jupiter
- Asteroids are bits of rock left over from the formation of the Solar System.
- Also has a dwarf planet called Ceres.
How was the sun formed?
- Formed from a huge cloud of hydrogen
- Gravity pulled the gas and dust together and the central core got very hot
- Particles were moving fast enough and nuclear fusion occured
Describe the life cycle of a star up to a main sequence star.
- Clouds of gas and dust are brought together by gravity
- Spiral together and form a prostar
- Temperature increases as the star gets denser as particles collide more often with greater force
- When the temperature is high enough hydrogen nuclei undergo nuclear fusion giving out lots of energy forming a star.
Describe the characteristics of a main sequence star.
- A main sequence star is at a period of equilibrium
- Energy released by fusion gives an outward pressure, this is balanced by the force of gravity pulling everything inwards.
- Lasts billions of years
What is gravitational collapse?
Gravity pulling everything inwards.
After a main sequence star is formed, what can be formed?
Red giant or red supergiant
- Hydrogen in the core runs out and fusion of heavier elements occur. Star swells up and turns red as the surface coosl
- Small to medium sized stars (e.g. Sun), form red giants
- Bigger stars form Red Supergiants - they glow brightly as more fusion occurs and they expand and contract several times.
What happens when a red giant runs out of fuel for fusion?
- It becomes unstable and ejects its outer layer of dust and gas in the form of a planetary nebula.
- Leaving behind a dense solid core called a white dwarf which eventually cools and fades away.
What happens to red supergiants when they run out of fuel?
- They collapse into themselves and have a massive explosion called the supernova.
What does the supernova do?
- Throws layers of gas and dust into space, leaving a dense core called a neutron star
- If the neutron star is big enough it will become a black hole - super dense point in space that even light can’t escape from it.
