galaxies and the universe
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Galaxies and the Universe. Spectra of Science Amole 2013. The Hierarchy. The Universe. The sum of all space, matter, and energy that exists, has existed, or will exist There is only one You are part of it too! We see it as it was in the past Contains many other galaxies - PowerPoint PPT PresentationTRANSCRIPT
Galaxies and the Universe
Spectra of ScienceAmole
2013
The HierarchyUniverse
Galaxy
Stars
Solar System
Planet
World
Continent
Country
State
City
The Universe
• The sum of all space, matter, and energy that exists, has existed, or will exist
• There is only one• You are part of it too!
• We see it as it was in the past• Contains many other galaxies• Most of it is empty space
The Hubble Telescope• A reflecting telescope that was placed into orbit in 1990• Sends images and measurements back to Earth
electronically
• A deep image of an “empty” portion of the sky reveals thatthe universe is filled with galaxies
• The light we see from the most distant galaxies has traveled approximately 10 billion years to reach us
Galaxies
• A collection of stars, dust, and gas bound together by gravity
• We live in the Milky Way galaxy• There may be more than 100 billion galaxies• Not spread out evenly through space; exist in
clusters– Clusters can join and form superclusters
Fun Fact:If you counted 1,000 galaxies a night, it would take 275, 000
years!
Fun Fact:The Milky Way is part of a
cluster called the Local Group.
The Milky Way Galaxy
Galaxy Types
Spiralhave arms of
stars, gas , and dust that curve away from the center of the galaxy in a
spiral patternEx. – Milky Way
Ellipticalshaped like spheres or eggs; have almost no
dust or gas between
stars; contain old stars
Irregularfaint galaxies
without a definite shape; smaller than
the other types of galaxies;
contain fewer stars
The Big Bang Theory• Occurred 10-20 billion years ago• Before there was nothing• No space; No time• Out of nothingness came an explosion
of energy in all directions• This energy gave rise to all the matter
we know today • Thought to have expanded within a
second from something the size of a spec of dust to the size of our solar system
Misconception Alert:Describing this theory as
the “Big Bang” is a misnomerbecause there really was not an explosion, just a release of
energy
The Big Bang
• After 3 minutes, protons and neutrons began to fuse to form the nuclei of hydrogen and helium atoms
• About 300,000 years later, temperatures were cool enough for complete hydrogen and helium atoms to form
• Photons escaped from matter about the same time, and light existed for the first time
The Big Bang
• After under a billion years the first stars form– They live and die slowly creating heavier elements
• Galaxies and clusters also begin to slowly follow
The Evidence• Edwin Hubble
determined that other galaxies exist, besides the Milky Way
• He observed that galaxies were moving away from each other
– Hubble Law – the farther away a galaxy is, the faster it is moving away from us; supports the Big Bang Theory
The Evidence• Hubble found spectral lines shifted
towards red
The Evidence
• Explained by the Doppler Effect– Objects that are moving away from us
emit longer wavelengths– Toward the red end of the spectrum
The Evidence
• Arno Penzias & Robert Wilson accidentally detected faint radiation on a radio telescope in 1965
• Determined that the radiation was leftover thermal energy from the “big bang”
The Fate of the Universe
1. The universe will keep expanding forever
2. The expansion of the universe will gradually slow down, and approach a limit in space
3. The universe will stop expanding and start to fall back in on itself
The fate will depend on mass!
The Fate of the Universe1. Too much = gravity
will cause everything to collapse on itself
2. Too little = not enough gravity to stop expansion
3. Just right = it will slow down, but never really stop
Einstein’s Theory of Relativity• Mass curves space– Think about how a mattress reacts when
you sit on it• During a solar eclipse scientists
noticed stars were in different positions than expected
Interstellar Matter• The gas and dust located between
stars and galaxies
Quasar• The most distant and radiant objects
in space• Discovered by the radio waves that
they emit• May be infant galaxies• May have huge central black holes
Dark Matter• Highly debated• Scientists have evidence that there may be
more matter than just that that is visible• As much as 90% of universe may be dark
matter• Could be planets, black holes, or brown
dwarfs (stars that never start fusion)
Astronomical Unit (AU)• unit of distance equal to the average
spacing between the Earth and the Sun• equal to about 150 million kilometers (93
million miles)• light takes about eight minutes to cover
this distance
150 million km(93 million mi.)
The Earth animation
is not rotating in the correct direction;it should
be rotating from west
to east
Light Year• the distance that light travels in one year
in a vacuum, which is about 9.5 trillion kilometers (6 trillion miles)– The Milky Way Galaxy is about 100,000 light
years in diameter• the speed at which light travels this
distance is about 300,000 km/sec (186,000 mi/sec)
Fun Fact:The second closest star to
the Earth is a little over four light years away.
Parsec• unit of distance equal to about 3.26
light years (or 206,265 AU)
Parallax• the apparent shift in position of an
object when viewed from different locations
• used by astronomers to measure distance Try This:
Focus on the star to the left. Open and close your eyes in an alternating manner. What do you notice about the star’s
position?