History of Universe & Solar System Flashcards
3 ideas important in framing universal context:
- Universe is vast & old
- Elements of life are widespread
- Same physical laws that operate on Earth operate throughout universe
Primary lesson of Copernican revolution?
We are not the center of the universe.
Definition of galaxy?
Great island of stars in space, all held together by gravity and orbiting a common centor.
Local gropu?
Groups of galaxies. Our local gropu is lcoated in the outskirts of the Local Supercluster, called Laniakea
Superclusters?
The regions in which galaxies & galaxy clusters are most tightly packed.
Universe?
Sum of all matter and energy.
What key points doe sthe voyage model teach us?
- Sun is larger than any of planets
- Planets vary a lot in size
- Emptiness in our solar system
Star?
Large glowing ball of gas that generates heat and light through nuclear fusion in its core.
When can an object be considered a planet?
- It orbits a star
- It is large enough for its own gravity to make it round
- Has cleared most objects from its orbital path.
What is 1 light year?
9.46 trillion kilometers.
How do you calculate how fast something can travel / what distance?
Distance = speed x time
Nearest star system?
Alpha Centauri
What two types of evidence are there for the big bang?
- Universe must have been hotter and denser when it was smaller, with high temperature and density. As it cooled down it left a faint glow of radiation called cosmic microwave background which is detected and studied.
- Calculations that run backward allows scientists to predict when chemical elements should have been born. First soup contained 3/4 hydrogen and 1/4 helium.
How is a star born?
Gravity compresses material dense enough to generate energy by nucleaur fusion.
What is nucleur fusion?
A process in which lightweight atomic nuclei smash together and stick/fuse together to make much heavier nuclei.
How are planets/is a galaxy born?
Planets may be born at the same time as stars. The natural spin of an interstellar cloud keeps some of its gas spread away from its center while shaping it into a flattened disk.
What happens after a star is born?
It shines with energy. During most of it’s life nucleur fusion combines hydrogen nuclei to make helium nuclei (4 hydrogen for 1 helium because helium nucleus has slightly less mass). A small amount of energy has disappeared and becomes energy in accordance with E = mc^2.
How does a star die?
It lives until it has burned through all fuel. When everything has been exhausted, a star blows much of its content back into space. Massive stars die in huge explosions called supernovas. Returned matter become part of new clouds of gas and dust from which new stars can be born.
What are 4 features of our solar system?
- Patterns of motion
- Two types of planets
- Asteroids & Comets
- Exceptions to the trend.
Two types of planets?
Terrestrial & Jovian.
What are asteroids?
Chunks of rock & metal that orbit the Sun in much smaller size than planets.
Comets?
Like asteroids but contain large amounts of ice and are found much further than the Sun.
Two places where comets come from in our solar system?
Kuiper belt; donut shaped region beyond Neptune
Oord cloud; spherical region that extends to thens of thousands of times Earth’s distance from the Sun.
What type of patterns of motion are there?
- All planets orbit the Sun in nearly same plane and same direction.
- All have nearly circular orbits
