Hubble, Expansion of the Universe
What is a nebula?
A large collection of gas and dust
What were the first three types of particles that existed in the early universe?
Quarks, electrons, elementary particles
What is a galaxy?
A large clump of stars
What is a baby planet called?
Planetesmal
How old is the universe?
13.8 billion years
Which piece of evidence told Hubble that the universe was expanding?
He saw a redshift occur in light coming from distant galaxies - space between observer and source is stretched
Why did it take a long time for neutral atoms to form?
The universe was too hot and dense and needed to cool
What were the main elements in the early universe that eventually formed our sun?
Hydrogen and Helium
How are elements heavier than iron created?
Through a supernova explosion
What is the most common star type in the milky way?
Red Dwarf
How can scientists determine what is inside of a star?
They look at the star's spectrum, either absorption or emission. The spectrum gives a pattern of lines characteristic to each element in it.
What was considered the first light in the universe?
Cosmic background radiation (CMB)
How do stars get their energy, and how do they die?
They do fusion reactions within their core. They die when they run out of elements to fuse (reach iron).
What are the three parts of accretion theory?
1) Rotating cloud of dust
2) Solar winds
3) Coalescence
How many stars are in the milky way?
100 billion
Which colour of light in the visible spectrum has the shortest wavelength and longest frequency?
Purple/violet light
Why is the universe temperature 3 Kelvin and not zero? What is important about this?
Cosmic background radiation leftover from the big bang - it is the major piece of evidence for this theory
What are the two main forces that keep a star stable?
Inward gravity, and outwards pressure - when gravity becomes too much the star collapses
How did the sun form, according to accretion theory?
A rotating cloud of dust accumulated and eventually formed our sun
What three things are comets made of?
Dust, rocks, ice
Why do sirens sound low pitched as they pass you? Describe what happens to the sound waves.
The sound waves will elongate and spread out, this effect is called the Doppler Effect.
Why could light not escape for a long time after the big bang?
The universe was too dense
What are the two types of objects a supernova can become?
A black hole or a neutron star
Why is fusion only possible up to iron, except for in a supernova explosion?
It requires too much energy to do fusion, supernovae explosions produce enough energy to be able to fuse heavier elements but no other known process can
What colour are the hottest stars?
Blue