The _________ likely way to cause a nebula to collapse is by the introduction of energy and particles from the explosion of a nearby star or colliding with another nebula.
The _____________ zone of the sun is so dense that it takes a long time for energy to pass through it.
It is believed that much of the water present on early _________ was formed from condensed volcanic gases.
A planet with a __________ orbit has a long period of revolution and a planet with a ________ orbit has a short period of revolution.
Kepler's ________ law says that if we know the period of revolution of a planet, the planet's distance from the sun can be calculated.
The ____________ separated into layers because its interior was a liquid and all the dense materials like nickle an iron sank to the center while the lighter material floated to the surface.
______________ like stars and planets are shaped like spheres because the gravity is so great that it causes the material to be pulled towards the center from all sides.
A solar system begins as a _________ which is pulled together by gravity to form a solar nebula where bits of dust and rock from planetesimals that even eventually develop into planets which are made of rock and gas.
____________ is a force that all matter has. It is increases when objects move closer to each other.
Impacts of ___________ into each other brought new material to the planets, dug craters and released energy.
____________ is the process by which two molecules fused together to make a new element. This process releases more energy than any other process known to man.
The ____________ is the outermost layer and has the lowest density of all of the earths layers.
As the ______________ formed solar winds caused by the sun blew the lighter gas materials to the outer part of the solar system. Thus, the remaining dust created the rocky inner planets while the outer planets form from gas.
_________ are icy planetesimals that come from outer parts of the solar system on their journey around the sun.