P8 (pmt) Flashcards
What is red-shift?
An observed increase in the wavelength
of light from distant galaxies
What two things can be said about the motion and
wavelength of emitted light from a galaxy, the further
away it is?
● The further away a galaxy is, the faster it is
moving
● The further away a galaxy is, the greater
the observed increase in wavelength
What does red-shift provide evidence for?
● Provides evidence that the universe is
expanding
● Supports the Big Bang theory
What does the Big Bang theory suggest?
The entire universe started from a very
small, hot and dense region in space.
Compare the observed red-shift of two galaxies, one
further away than the other
● The galaxy that is further away is
travelling faster
● The observed red-shift is greater the
further away it is
What did scientists observe to provide evidence that
the universe is expanding at an ever faster rate?
They observed supernovae, which
suggested that galaxies are moving
away at an ever faster rate.
Prior to observations of supernovae, what was
believed about the rate of expansion of the universe
and why?
● The rate of expansion was expected to
occur at an ever slower rate
● It was thought that gravitational forces
would cause this slowing down
What two ideas could explain the universe’s ever
increasing rate of expansion?
● The existence of energy and mass that we
can’t detect, known as dark matter and dark
energy
● These ideas are still being developed by
scientists and are not yet fully understood
Which galaxy is our solar system part of?
The Milky Way galaxy.
Which galaxy is our solar system part of?
How many planets make up our solar system?
Eight (plus the dwarf planets).
What do the planets in our solar system orbit around
and what type of body is it?
● The planets orbit around the sun
● The sun is a star
What type of force pulled together the cloud of dust
and gas to form the Sun?
]
Gravitational force of attraction.
What word is used to describe a cloud of dust and
gas?
a nebula
What type of reactions take place at the start of a
star’s life cycle as dust and gas is drawn together?
Fusion reactions.
What factor determines the type of lifecycle a star
undergoes?
The size of the star
Which two phases do all stars of the same or greater
size than the sun undergo?
- Protostar phase
2. Main sequence phase
What do stars of a similar magnitude to the sun
become at the end of their life-cycle?
A black dwarf.
What two things can stars much bigger than the sun
become at the end of their lifecycle?
- Neutron star
2. Black hole
What two phases do stars of similar size to the sun
go through between being a main sequence star and
a black dwarf?
- Red giant
2. White dwarf
What two phases do stars of greater size than the
sun go through between being a main sequence star
and a neutron star/black hole?
- Red super giant
2. Supernova
What are produced during the fusion processes in a
star?
All of the naturally occurring elements
What condition is required for fusion reactions to
occur in a star?
Very high temperatures
How are elements heavier than iron produced?
In a supernova.
