This is a very valid hypothesis for many reasons. One is that solar systems form from massive amounts of dust, ice, and debris that eventually form into planets and such. This means it is very possible for this 'excess material' if you will to have moved into orbit behind Neptune.
Answer:
The Greenhouse Effect Revisited. When solar energy strikes the planet during the day, the ground, highways and other objects get hot and absorb that energy. As the sun goes down, the Earth cools by giving off infrared radiation. Because greenhouse gases absorb part of this radiation, the atmosphere warms and keeps the Earth from getting too cold.
When you keep raisin in water and the raisin gets puffed.
Movement of salt-water in animal cell across our cell membrane.
No, it only does when entering an atmosphere