Space Flashcards
(27 cards)
What is a star?
A star is a large ball of gas - mostly hydrogen and helium that undergoes nuclear fusion
What is a light year?
The distance travelled by light, in a vaccum, in 365 days
What is a parsec and what is it used for?
A parsec is 3.26 light years (ly) - used to figure out how far a star is - with the sun as reference
How can stars differ from each other?
They can vary in size, mass, temperature and brightness
If a star is bright, what does that indicate?
A brighter star indicates a higher apparent magnitude
How does a star get energy?
The gases that make up the star are constantly reacting at the core and provide energy for the star when it undergoes nuclear fusion - this energy is emitted as light, which is what we see in the night sky
What is nuclear fusion?
When two light atomic nuclei join together to form a single heavier nuclei.
What does a stars brightness mean? - Apparent magnitude
The brightness of a star viewed from Earth can be measured using a scale called the apparent magnitude scale - a measure of how bright it “appears” to be. The sun is the brightest star we can see, and it has an apparent magnitude of -27. The more positive the number, the dimmer the star.
What does a stars brightness mean? - Absolute magnitude
Measures the brightness of a star as if they are all the same distance from Earth - the actual brightness/luminosity. If a star is hotter and further away it will have a higher absolute magnitude
What does a stars colour mean?
The colour of a star depends on its surface temperature
What stars are the hottest/coolest?
Hotter stars are blue and colder stars are red - can use the Hertzsprung Russel diagram to show this
What is a galaxy?
When groups of stars are held together by gravity
What is a nebulae?
A giant cloud of gas and dust in space
What do small stars do when they die?
Small stars will cool and die, forming white and black dwarfs
What do big stars do when they die?
Big stars will explode into novas and supernovas - releasing large amounts of energy and light
What happens to the rest of the star when it dies?
The remaining core of the star becomes a neutron star
How are stars born?
When there is a nebulae - a cloud of gas and dust made of hydrogen. lots of hydrogen atoms = greater attraction force - there is a lot of pressure in the gas cloud, causing it to heat up. when there is enough heat, the atoms form together to make helium - this nuclear fusion releases large amount of heat and light energy
Draw the life cycle of a star:
ok
How can you determine the elements present in the universe?
Elements will absorb light in specific wavelengths - creating an absorption spectrum, when they return to a stable state, they release the same wavelengths as an emission spectrum
What is the Doppler effect?
The change in the frequency of a wave as the object moves closer or away from the observer
If an object is moving away from Earth, what way will it shift on the absorption spectrum?
An object moving further away means its wavelength will increase, the greater the redshift, the faster the object is moving away
What is the Big Bang theory?
The universe developed from a small dense singularity into a massively expanded space
What are the 3 pieces of evidence for the Big Bang theory?
- Expansion of the Universe
- Cosmic Microwave Background Radiation (CMBR)
- Mixture of elements - abundance of H and He
Evidence of the Big Bang - Expansion of the Universe
Redshift in galaxies - moving away from us. Light from an object moving away from us appears to have a longer wavelength - doppler effect.
