Notes: The Universe

OBJECTIVE: EXLAIN HOW THE UNIVERSE WAS CREATED.

The Universe

• The universe is everything that exists everywhere. It includes all of space, matter, and energy that there ever was and ever will be.

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The known universe

How did the Universe Begin?

• The Big Bang Theory: About 13.7 billion years ago, all matter was compressed to about the size of a period. Then it exploded releasing all of the matter and energy in our universe.

The Big Bang Theory

• As the universe expanded, it began to cool. After about 200 million years, gravity cause the first stars and galaxies to form.
• All matter in the universe was created during this explosion.

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Evidence of the Big Bang

• The ever-expanding universe. The matter in the universe is still expanding or moving away from a center point.

Evidence of the Big Bang

• Cosmic Background Radiation. The leftover thermal energy from the big bang that is distributed in every direction.

Evidence of the Big Bang

• The amount of hydrogen and helium in the universe is consistent with what we predict would have been created in the Big Bang.

Evidence of the Big Bang

• Older galaxies are very different from newer galaxies, we know this by studying the light that comes from them.

Question: How long ago did the big bang happen?

• The big bang happened…

Galaxies

• Galaxy: A group of stars, star systems, dust, and gas bound together by gravity.

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Galaxies

• Spiral: Bulge in middle with arms.
• Elliptical: Oval and older, mostly stars.
• Irregular: No regular shape.

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The Milky Way

• We are part of a galaxy called the Milky Way, it is over 100,000 LY wide and has over 100 billion stars swirling around a giant black hole.

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Question: What is a galaxy?

• A galaxy is…

Nebula

• Nebula: A large cloud of gas and dust spread out in an immense volume.
• Often times, gravity will pull the gas and dust together forming a star.

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Stars

• Star: When gravity pulls gas and dust together becoming so dense and hot that nuclear fusion starts.
• Nuclear fusion is the process in which atoms of hydrogen combine to form helium, releasing energy.

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Stars

Lifecycle of a star.

• Low/Medium Mass Protostar🡪Small/medium Star 🡪Red Giant 🡪 Planetary Nebula 🡪 White Dwarf.
• Hi mass protostar 🡪 Large Star 🡪 Supergiant 🡪 Supernova 🡪 Neutron Star or Black Hole.
• Hotter stars are blue, cooler stars are red (our sun is yellow).

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Stars

Stars

All of the light that we see in the universe is produced by stars. The moon lights up because it is reflecting the light from the sun.

Question: What is a star?

• A star is…

Measurements

• Lightyear: The distance light travels in one year, about 6 trillion miles.
• Astronomical Unit or AU: The distance between the sun and Earth, about 93,000,000 miles.

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Measurements

• Parallax: the apparent change in position of an object when you look at it from different places, the less the star moves, the farther it is.

Black Holes

• Black Hole: an object with gravity so strong that nothing, not even light, can escape. Immense matter compressed into a tiny space.

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Composition of the Universe

• @68% = Dark Energy (Scientists aren’t exactly sure what it is other than it makes up space)
• @27% = Dark Matter (Scientists aren’t exactly sure what it is other than it affects gravity)
• @5% = Matter as we know it.

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Our Solar System

• Our Solar System consists of the sun and all of the objects that obit the sun including the 8 planets and their moons, the Kuiper Belt, and the Oort Cloud.

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The Sun

• The sun most likely formed about 4.6 billion years ago when gravity brought gas and dust together. It can fit over a million Earth’s inside it, and it makes up about 99% of the mass of the solar system.

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The sun

The Sun

• The sun accounts for most of the light in the solar system and the gravity that holds the planets in orbit. Nuclear fusion should keep the sun burning for another 5 billion years.

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