Question

nebular theory
in 1796, laplace formed a hypothesis that stated that the sun and planets condensed out of the same spinning _, or cloud of gas and dust that the sun did.
formation of the sun
the cloud of gas and dust that developed our solar system is called the _

• formed 4 - 5 _ years ago.
• the _ began forming at the center of the nebula.

heat from collisions and pressure from _ caused the center of the solar nebula to become hotter and denser.
hydrogen _ began and the sun was formed.
_ % of the solar nebula became our sun.
formation of the planets

• small bodies of matter in the solar nebula.
• the joining of planetesimals through collisions and force of gravity.
• smaller bodies that orbit planets.
• formation of the planets

the distance between a protoplanet and the developing sun influenced the _ of the planet that formed it.

• 4 protoplanets closest to the sun contain heavy elements like _
• icy material of outer protoplanets consisted of h and he, and frozen gases (water, methane, and ammonia)

inner & outer planets
inner planets have few _ because of their proximity to the sun.
outer planets retain original gases because of their distance from the sun and large gravitational forces.

• _ giants.

formation of the solid earth
sources of heat:

• 1. produced when it collided with _
• 2. compression of _
• 3. _ materials.

gravity pulled molten iron toward the _
earth separated into 3 distinct layers.
formation of earths atmosphere
early atmosphere of hydrogen ( ) and helium ( ).
early atmosphere lost as a result of a solar explosion or _
the second atmosphere resulted from:

• 1. _ releasing water vapor, carbon dioxide, ammonia, and methane.
• 2. sunlight caused ammonia and water vapor to change to nitrogen ( ), hydrogen ( ) and some oxygen ( )

Explanation:

The text is about the nebular theory of the solar - system formation, including the formation of the sun, planets, the solid Earth, and Earth's atmosphere. Key concepts involve the solar nebula (a cloud of gas and dust), planetesimals, hydrogen fusion for sun - formation, and processes related to Earth's heat sources and atmospheric development.

Answer:

1. nebula
2. solar nebula; billion
3. sun; gravity
4. fusion
5. 99
6. planetesimals
7. accretion
8. moons
9. composition
10. iron
11. moons; gas
12. planetesimals; materials; radioactive
13. center
14. $H_2$; $He$; solar wind
15. volcanic eruptions; $N_2$; $H_2$; $O_2$