| A | B |
|---|
| The complete orbit of one heavenly body around another | Revolution |
| Time it takes for Earth to complete one revolution | 365 days |
| When an object rotates or spins on an axis. | Rotation |
| Time it takes for Earth to complete one rotation | 24 hours |
| _________ are caused by Earth's rotation | Day and night |
| __________ are caused by Earth's revolutions | The seasons |
| a large, hot ball of gas, which is held together by gravity and gives off its own light | Star |
| a number of stats that appear to form a pattern | Constellation |
| the distance light travels in a year | Light-year |
| about 9 trillion kilometers | Light-year |
| an enormous cloud of gas and dust in space | Nebula |
| that is the first stage of star formation | Nebula |
| a star that explodes, often a supergiant that has become unstable | Supernova |
| Gases found in the core of stars | Hydrogen and helium |
| an object whose gravity is so strong that even light cannot escape from it | Black hole |
| The color of the hottest stars in the universe | blue |
| The color of the coolest stars in the universe | red |
| the color of our star | yellow |
| Stars live until this age | 10 billion years |
| The age of our sun | 4.5 billion years |
| Millions or billions of stars, together with gas and dust, held together by gravity | Galaxy |
| The name of our galaxy | The Milky Way |
| Area of the sun's photosphere where we can see strong magnetic activity | Sunspot |
| the part of the sun we can see from Earth | Photosphere |
| the innermost part of the sun | Core |
| Nebula --> Main sequence star --> Supernova --> Black hole/neutron star/dwarf star | The four stages in the lifecycle of a star |
