astro Flashcards
What orbits the sun?
Planets, dwarf planets, asteroids and comets
What orbits the earth?
Moon, artificial satellites
How to calculate orbital speed?
Orbital speed = 2pi*orbital radius/time period
What is weight + equation for weight?
Weight is the force acting on an object due to gravitational attraction.
mass * gravitational field strength
Difference between asteroid and comet?
Asteroids are lumps of rock and metal
Comets are lumps of ice and dust.
How do stars begin?
Stars begin as a cloud of dust and gas called a nebula. They continue to clump together (and form a protostar) until the pressure and temperature is great enough for nuclear fusion.
What is nuclear fusion (for a nebla/star)
Hydrogen nuclei fuse together to form helium which releases large amounts of energy and creates great amounts of outward pressure.
The outward pressure then balances with the inward pressure (gravity) and is now stable and a main sequence star.
What happens after the main sequence to a star.
When the hydrogen in the star is used up, there is not enough outward pressure from nuclear fusion and it collapses under it’s own gravitational attraction, becoming unstable.
What happens to a collapsed star that is the around the same mass as the sun?
expands and becomes a Red giant (hydrogen fuel running out) -> white dwarf -> black dwarf
What happens to a collapsed star that has a larger mass than the sun?
expands and becomes a Red Super giant -> explodes into a supernova -> and becomes a neutron star, unless it was massive and then it becomes a black hole.
How are stars classified?
By colour (relates to temperature)
Red = cooler
Blue = hotter
What is absolute magnitude?
The absolute magnitude of an object is the magnitude an object would have if it were 10 parsecs away from Earth.
What is red shift?
Red shift is when the light source moves away from you/us, the light emitted will be shifted towards. the red end of the spectrum. This happens as the light waves are stretched out (lower freq. too)
