P1.3 Waves And The Universe Flashcards
How do planets orbits stars?
In ellipses.
What is the suns radius and mass?
Radius: 696000 km
Mass: 1.99*10(30)kg
What is a galaxy?
A collection of billions and billions of stars.
How big is the distances between galaxies?
Millions times bigger than the distances between stars.
How do scientists try to get clues about if any other life exists?
They use earth based telescopes or remote sensing techniques.
What does SETI stand for?
Search for Extra Terrestrial Intelligence.
What do SETI look for?
Narrow bands of radio wavelengths. They then look fo meaningful signals.
In what other ways do scientists look for evidence of life?
Spacecraft with probes- they send the data back
Robots- they take photos and collect soil and rock samples
What is a problem with using earth telescopes.
The atmosphere absorbs a lot of light from space.
Why is light pollution an issue for detecting stars?
Light pollution can make us unable to see dim objects.
Why is air pollution a problem for space observation?
Dust particles can reflect and absorb light coming from space.
Why are other types of EM wave telescopes useful?
We can see new parts of the universe and learn more about its structure.
What are x-ray telescopes good for?
Seeing ‘violent’ events in space eg exploding stars.
What are radio telescopes useful for?
They are responsible for the discovery of cosmic microwave background radiation (CMB radiation).
What doe bigger telescopes provide?
Better resolution.
What is a spectrometer?
A device that diffracts light given off by telescopes.
Why are spectrometers used?
To find out what a star is made of.
How does a spectrometer work?
When the light diffracts, dark lines are where the colours that it emits.
How are the dark lines on a spectrometer caused?
By light at those wavelengths being absorbed by the elements in the stars being absorbed.
What are the dark lines know as?
The absorption spectrum.
What are bright lines on a spectrometer?
The emission spectra. They are caused by extra light being emitted on those wavelengths.
What are the stages of a normal stars life?
Nebula Main sequence star Red giant Planetary nebula White dwarf
What is the sequence in a giant stars life?
Nebula Main sequence star Red giant Supernova Neutron star or black hole.
How do stars change from a nebula into a main sequence star?
When their own gravity makes the nebula spiral together and the gravitational energy is converted into heat energy so the temperature rises, which starts fusion.
How does a star go from a main sequence star to a red giant?
When the hydrogen in the core runs out, the star swells and cools.
How does a star go from a red giant to planetary nebula to a white dwarf?
The red giant becomes unstable and ejects its outer layer of dust and gas as a planetary nebula. This leaves behind a dense, solid core (a white dwarf) which just cools and disappears.
How does a star go from a red giant to supernova to a neutron star or black hole?
The red giant undergoes more fusion and forms heavier elements. They explode in a supernova. What is left is a very dense neutron star, or if the star was big enough, a black hole.
What is red shift?
Light from far away galaxies is more shifted towards the red end of the spectrum.
Why is red shift important?
It provides evidence that the universe is expanding.
Why is CMB significant?
The big bang theory is the only theory that can provide evidence for CMB,making it the accepted theory at the moment.
