- In Copernicus' heliocentric model of the solar system, orbits are _____ and the universe is ___
- As distance increases, gravitational attraction ___________.
- Which of the following has a life cycle-meaning they are born, live and then die?
- Helium fusion occurs at temperatures above?
- What causes the outward pressure that balances the inward pull of gravity in a star?
- What does Earth's hydroshpere represent?
- In Kepler's model, the sun is the center point that the planet revolves around.
- __________ are starlike objects that contain less than 0.08 solar masses an will never raise their core temperatures to the point that the proton-proton chain can begin. They fall in a gap between the low-mass M dwarf stars and the massive planets.
- Emission nebulae are also called __________ because they are composed of ionized hydrogen ?
- How many stars are in the Milky Way Galaxy
- The average star spends _____ percent of its life time on the main sequence.
- The lowest mass object that can initiate thermonuclear fusion of hydrogen has a mass of about ?
- How many days does it take Earth to revolve around the sun?
- What is the force that keeps the planit orbiting the sun?
- what type of celestial body is our sun?
- The average star spends what percentage of its life in the protostar stage?
- __________ is the thermonuclear fusion of hydrogen to form helium operation in the cores of stars on the main sequence that are more massive than the sun ?
- __________ are small luminous nebulae by nearby young stars ?
- gravity is the ____ force between any 2 objects
- True or False does the sun have a solid surface?