P2h: The Big Bang Flashcards
Evidence for galaxies moving away from us and what it means (2+1)
light from other galaxies shifting to the red end of the spectrum (lower frequencies) (Doppler effect) (red shift)
more distant galaxies generally show greater red shifts - they are moving away more quickly than nearer ones
whole Universe is expanding
What does the Big Bang theory account for? (4)
light from other galaxies shifting to the red end of the spectrum, showing they are moving away
more distant galaxies generally show increased red shifts - moving away more quickly than nearer ones, showing universe is expanding
estimating age/starting point of universe from current rate of expansion; but hard to tell how much speed of expansion has changed
Cosmic background radiation (CMBR) which is received from all parts of the universe
Describe the properties of a black hole (2)
high density due to large mass and tiny volume
strong gravitational attraction due to the large mass
Describe the start of the life cycle of a small star(4)
clouds of dust and gas(nebula) forced together by gravity to form a protostar
gravity causes the star to become smaller, hotter and brighter
when the core temperature is high enough, the hydrogen nuclei undergo thermonuclear fusion and join together to form helium nuclei, releasing lots of heat and light
long stable period: heat from nuclear fusion provides outward pressure to balance gravity pulling everything inwards - main sequence star occurs for billions of years until the core runs out of hydrogen
Describe the end of the life cycle of a small star (3)
hydrogen runs out and star swells into red giant (core contracts and outer part cools) (red as surface cools)
star unstable and ejects outer layer of dust and gas as planetary nebula
leaves behind hot, dense solid core - shines brightly as a white dwarf which cools down and eventually becomes black dwarf and fades away
Describe the end of the life cycle of a large star (4)
hydrogen runs out and star swells into red supergiants
start to glow brightly again as they undergo more fusion and expand and contract several times, eventually exploding in a supernova
throws outer layers of dust and gas into space, leaving behind a very dense core - neutron star
if star big enough, the core of the neutron star continues to collapse, becomes denser and forms a black hole
What type of stars shine longer and why
Small stars shine longer
they have less hydrogen but use it up at a slower rate
Ptolemaic model of the universe
ancient Greek astronomers believed Sun, Moon, planets and stars all orbited the Earth in perfect circles (geocentric model)
Copernican model of the universe
the Earth and planets all orbit the Sun, which is at the centre of the universe, in perfect circles (heliocentric model)
Evidence/observations that caused Copernicus and Galileo to develop new scientific models of the universe (3)
Galileo developed telescope w/ powerful magnification to see things that were previously too small to observe
he observed Jupiter w/ it; saw some stars in a line near the planet which never moved, suggesting they were moons orbiting
Jupiter
showed not everything was in orbit around the Earth - evidence that the Ptolemaic model was wrong
Explain why the theories of the Copernicus and Galileo models were considered controversial when they were announced (3)
weren’t popular as current model(Ptolemaic model) had been around for a long time
model was condemned by the church as it went against the Bible which said Earth was at centre of universe
-speaking out against the ideas of the church was considered blasphemy(a crime)
When and why were the Copernicus and Galileo models eventually accepted? (2)
adopted eventually after many years passed
gradually, evidence for the Copernican model increased thanks to more technological advances
