Match the words in the left-hand column to the appropriate blanks in the sentences in the right-hand column. Use each word only once.
1. Our solar system was created by the gravitational collapse of the____ .
2. Our Moon was most likely formed by a collision between Earth and a Mars-sized_ .
3. The first few hundred million years of the solar system's history were the time of the_ , during which Earth suffered many large impacts.
4. Mars was formed by the of smaller objects.
5. The era of planet formation ended when the remaining hydrogen and helium gas of the solar nebula was swept into interstellar space by the .
6. Ice can form from a gas through the process of .
7. Hydrogen compounds in the solar system can condense into ices only beyond the_ .
8._ allows us to determine the age of a solid rock.

Solar nebula is a cloud of gases and was created by the gravitational collapse of the dust and hydrogen in a form molecular cloud and has a hot dense center.

Planetesimals are solid objects that are formed by the debris from the disks and believed to have formed some 46 billion years.

The period of heavy bombardment is known to have been due to the intense spike of asteroids about 4 billion years ago. That lead to the formation of craters on earth and moon.

Accretion is the process by which the growth increase and is the accumulation of layers of matter over the surface.

Solar winds are those blows from the surface of the sun and consist of charged particles.

Condensation is a change in the physical state of gas into the liquid phase.

Frost line is the depth of the water is expected to freeze and can cool enough to form hydrogen compounds to solid ice grains.

The radiometric dating technique is allows us to determine the absolute age of rocks and carbon contents.