space Flashcards
(19 cards)
what are stars initially formed from?
a cloud of dust and gas called a nebula.
what is a protostar?
a nebula that has collapsed under it’s own gravity.
how does a protostar turn into a main sequence star?
the temperature increases as the protostar gets denser from gravity until the temperature is high enough to cause nuclear fusion. hydrogen nuclei forms helium nuclei
what is a main sequence star?
a star in a stable period where the outwards pressure from nuclear fusion balances with gravity. lasts several billion years
how is a red giant formed?
when a main sequence star runs out of hydrogen for fusion reactions its core shrinks and heats up causing the outer layers to expand and cool. *causing the red appearance.
how is a white dwarf formed?
when a small to medium star ejects the outer layers of dust and gas leaving being a hot dense solid core.
how is a black dwarf formed?
when a white dwarf cools down and no longer emits much energy.
how is a supernova formed?
big stars start to glow again from new fusion reactions such as with helium expanding and contracting multiple times eventually exploding in a supernova.
how is a neutron star or black hole formed?
an exploding supernova ejects layers of dust and gas leaving a dense core a neutron star if the star is large enough it will become a black hole.
what is the solar system?
the sun and everything that orbits it.
what are the 8 planets?
mercury venus earth mars jupiter saturn uranus neptune.
what are dwarf planets?
planet-like objects that orbit stars but don’t meet the requirements for being a planet.
what are moons?
a natural satellite that orbits a planet.
what is a galaxy?
a massive collection of stars held together by gravity.
what is gravity?
the force of attraction between 2 objects with mass.
how do things orbit?
gravity is constantly pulling an object inwards but because the object is always moving forward it follows a curved path and stays in orbit.
how does speed change the size of an orbit?
fast moving objects orbit in a smaller radius than slow objects.
why do we think the universe is expanding?
when looking at light from distant galaxies we find the wavelength has increased to be longer than it should be towards the red end of the spectrum which is called red-shift. as space expands light waves are stretched out making them longer
why do we think the universe started with a bang?
we know all galaxies are moving away from eachother which suggest something an explosion got them moving.
