The Universe, the Big Bang,
Stars, and Galaxies
“The universe is a pretty big place, it’s bigger than anything
anyone has ever dreamed of before. So if it just us, seems like an
awful waste of space, right?”
Contact opening scene (2:57)
Last scene Men in Black (1:10)
Universe
The Hubble Ultra Deep Field, or HUDF, is an image of a small region of space in the constellation Fornax, composited from Hubble Space
Telescope data accumulated over a period from September 3, 2003 through January 16, 2004. It is the deepest image of the universe ever
taken in visible light, looking back in time more than 13 billion years. The HUDF contains an estimated 10,000 galaxies. The total field of view
represents only 1 ten millionth of the total sky.
• consists of all matter, empty space, and
energy that exists
• objects are so far away, we are seeing
what they looked like millions of years
ago
• the visible universe is a region some 28
billion light years in diameter.
– it takes one year for light to travel 5+ trillion
miles (a light year)
• around 14-20 billion years old
• is expanding faster and faster
The Big Bang Theory
• Origins
– began with a large explosion called the
big bang theory
– only energy before this, no matter
– first hydrogen and helium were formed
– larger elements were formed later by stars
• Evidence
1. is expanding, therefore must have been
smaller at one point
• evident by galaxies’ red shift
– most look red because they are moving away from us
• if they were moving towards us, they would look
bluer (blue shift)
2. cosmic background radiation
– scientists found “noise” in our galaxy that was
the cosmic microwave background radiation
predicted by the Big Bang theory
3. most elements in universe are H and He
– when stars reach the end of their life cycle,
they distribute C, O, and Fe into the universe
•
if the universe was older, there would be more C,
O, and Fe
Stars
Show Planet and
Stars Scale video
• Closest star to Sun is Proxima Centauri
– 4.2 light years away
• life cycle varies depending on the size
• all begin life inside a huge cloud of gas (mostly
hydrogen) and dust called a nebula
• then turns into a protostar
– H is converted to He
– gravity squeezes the atoms of a star so tight
that the electrons are stripped away and the
bare nuclei of atoms almost touch each
other
• The Hertsprun-Russell (H-R)
Diagram
– graphs the brightness and
temperature of stars
– helps astronomers understand how
stars change over time
• for average, Sun-sized stars
– eventually runs out of H
– core contracts, gets hotter making elements
up to Fe
– expands outwards making a red giant
– hydrogen fusion stops
•
•
•
•
no more energy exploding outward
gravity pulls matter inwards
VERY high density, bright, and is called a white dwarf
outer layers often expand and drift away creating a
planetary nebula
• for larger stars
– elements up to iron are fused together
– eventually may turn into a supernova
• quickly collapses because run out of energy
and gravity is now the strongest force
– core collapses and then rebounds outward with a
shock wave that makes a bright explosion
(supernova)
– at this point, the heavier elements are finally created
• if the leftover core is very, very dense, it may
form a very small neutron star or a black hole
with VERY powerful gravity
Galaxies
• a collection of millions or billions of stars
• we are in a spiral galaxy called the Milky
Way (Monte Python Galaxy song - 2:43)
• nearest to us is the Andromeda galaxy
– 2.2 million light years from earth
• galaxies can also be elliptical and
irregular shaped.
The End