Topic 7: Astronomy Flashcards
What is a galaxy?
A collection of stars, gas, and dust held together by gravity.
What is the name of our galaxy?
The Milky Way.
What is the Big Bang Theory?
The theory that the universe began from an extremely dense and hot state and has been expanding ever since.
What evidence supports the Big Bang Theory?
Redshift of galaxies and cosmic microwave background radiation.
What is a star’s life cycle for a star like the Sun?
Nebula → Main Sequence Star → Red Giant → White Dwarf.
What is a supernova?
A massive explosion that occurs at the end of a large star’s life.
What are black holes?
Regions of space with gravity so strong that not even light can escape.
What causes redshift in light from distant galaxies?
The stretching of light waves as galaxies move away due to the universe’s expansion.
What force keeps planets in orbit around the Sun?
Gravitational force.
What is a light year?
The distance light travels in one year (9.46 × 10^12 km).