space Flashcards
how long ago was the universe created?
the universe was created 13.7 billion years ago
what is thought to be at the center of the milky way (our galaxy)?
a black hole (also known as the galactic center)
how long ago was our solar system formed?
our solar system was formed 4.6 billion years ago
what is the solar system?
the solar system is any object that is bound by gravity to a sun.
name 4 objects that are in the solar system?
any 4 from:
- one star - the sun
- 8 planets
- natural satellites called moons that orbit planets
- dwarf planets
- comets
- asteroids
- satellites
- dust, ice and rocks make up the remaining mass
what are artificial satellites?
man made objects that are put into space, for example, ISS
what is nebula?
a nebula is dust and gas clumped together
what force pulls dust and gas together to form a star (the sun)?
gravitational attraction
what do fusion reactions (joining) lead to?
fusion reactions lead to an equilibrium between the gravitational collapse of the star and the expansion of the star due to fusion energy
the sun, like all stars, releases energy through _______ ______ reactions in the core.
nuclear fusion
what two isotopes of hydrogen are used in nuclear fusion?
deuterium and tritium are involved in nuclear fusion
explain the process of nuclear fusion in stars?
two isotopes of hydrogen (deuterium and tritium) are forced together under high temperatures and pressure. nuclear fusion occurs to form helium and a neutron.
a tiny amount of mass is converted into a large amount of energy, which is why stars emit a lot of energy.
the heat produced in the fusion process make the star ______ through thermal pressure.
expand
_____________ __________ is pulling the mass of the star inwards.
gravitational attraction
how does a star remain stable?
as long as the inward force of gravity is the same as the outward force generated by fusion the star remains stable
a _________ ______ occurs at the end of a red giant’s life.
planetary nebula
what happens when a red giant collapses?
when a red giant collapses, its outer layers shed off and what remains is a white dwarf
what is a white dwarf?
a white dwarf is a very hot, dense star
what is a black dwarf?
a black dwarf is a hypothetical star, created when a white dwarf cools so it no longer emits heat or light.
why do scientists believe that there aren’t any black dwarfs?
the time required for a white dwarf to become a black dwarf is around 13.7 billion years.
what is the different between stars and ‘giant’ stars?
‘giant’ stars are brighter and larger.
after hydrogen has been used up in the core of a giant star, it becomes a ___ __________
red supergiant
what is the death of a large star called?
a supernova
how are supernovae formed?
- in the core of a red supergiant, lighter elements fuse to form iron
- iron nuclei absorb energy when they fuse and so the process slows down
- decreased pressure in the core means the outer layers aren’t held up and they collapse inwards which sets off an explosion
the longest, most stable period of a star’s life is called a ____ ________ ____ .
main sequence star
how is a redgiant formed?
- whilst hydrogen converts to helium it creates heat and light*
- a star expands as it grows old
- as the core runs out of hydrogen and then helium the core contracts
- the other layers expand thus becoming cooler and less bright, forming a redgiant
place these in order of life cycle of a star: protostar red super giant supernova nebula black hole main sequence star neutron star
nebula protostar main sequence star red super giant super nova neutron star or black hole
