Astronomy Flashcards
What is a star
A hot bright ball of gas held together by gravity, it produces light by nuclear fusion in its core
What is a planet
A natural satellite that orbits a star
When is something considered a planet
It needs to be large enough to be round, and have cleared its orbit
What is a moon
A natural satellite that orbits a planet
Where are we located in the universe
Solar system, milky way, local group, virgo supercluster in the observable universe
What is the difference between geo and helio centric models
Geo is where earth is at the center and helio is where the sun is at the center
What are optical telescopes
They collect light and focus it to form an image
What are radio telescopes
Receive radio waves emitted by stars and other object and form and image
What is nuclear fusion
When two nuclei fuse under immense pressure to produce light and heat energy
What is gravity
The force of attractions between two objects, it is a weak force
How do stars resist gravity
Inside of stars stellar nuclear fusion takes place which produces energy/force which pushes outward and gravity pushes inward so they balance eachother out
What is spectural class
How stars are classified based on colour, the colour is based on temp of star
What is the life cycle of a small mass star
Interstellar gas cloud gets compressed by gravity to form a small mass star then the hydrogen burns and once it runs the outer layers are removed and a planetary nebula and a white dwarf are formed which the cools and becomes a black dwarf
What is the life cycle of a medium mass star
Interstellar gas cloud gets compressed by gravity to form a medium mass star then the hydrogen burns and helium builds up in core which then makes the star expand to be a red giant then once the helium runs out the outer layers are removed forming a white dwarf and planetary nebula
What is the life cycle of a large star
Interstellar gas cloud gets compressed by gravity to form a large mass star then the hydrogen burns and helium builds up in core which then makes the star expand to be a red giant then once the helium runs out carbon is fused in the core and other elements until it gets to iron fusion, when the iron is fused it takes energy and the star implodes and causes a super nova and the star could become a white dwarf, a neutron star or a black hole depending on how big it was
What is a neutron star
A very dense star where the force is so great protons and electrons form neutrons
What is a black hole
They are formed when a massive star collapses and forms a black hole. They are very dense and have such great gravity light cant escape
What is the evidence for a black hole
- Gravitational lensing where the light around it gets distorted and the stars look identical around black holes
- Binary star systems where if 2 stars are close to eachother and one becomes a black hole the other will be stripped of its stellar mass
What is the colour of a star based on
Its temperature, so if it is very hot it emits lots of energy at high frequencies which are ultra violet and violet on the spectrum and so they appear blue and white, but cooler stars emit energy at lower frequencies and are in the red and infrared on the spectrum
What is the difference between apparent and absolute magnitude
Apparent magnitude is how bright a star appears from Earth, while absolute magnitude is how bright it would appear if all stars were observed from the same distance
What factors determine brightness
How much light the star emits and how far away it is
What is a spectrometer
A spectrometer breaks starlight into a spectrum, and by studying the pattern of colors and dark lines, we learn what stars are made of and how they behave.
What is a light year
The distance light travels in one year (9.46 trillion km)
What is the speed of light
300 million metres/second
