Astronomy Flashcards
What units are used to measure the size of the universe?
For short distances, i.e. Within a solar system , astronomical units are used. For long distances, i.e. Interstellar and intergalactic distance, the units of measurement is light years.
What is the physical composition of the universe?
Planets -> stars -> nebulae -> galaxy -> universe
What is a lightyear?
A light year is equivalent to the distance that light travels in one year, which is nearly 6 million million miles.
How are stars formed?
Stars form from nebulas.
What are nebulas?
Nebulas are regions of concentrated dust and gas.
What is the 2nd step in a star’s life cycle?
As the nebula contracts, a small star is formed called a protostar.
What is the 3rd step in a star’s life cycle?
The star joins the main sequence undergoing nuclear fusion where hydrogen is converted into helium.
What is the 4th step in a star’s life cycle?
Stars begin to die when they run out of hydrogen. As a result of this they start making heavier elements such as carbon and oxygen and gravity begins to take over.
How do low to medium mass star’s die?
Main sequence -> Red giant -> Planetary nebula -> White dwarf
How do high mass stars die?
Main sequence -> Red super giant -> Supernova -> Black hole or Neutron star
