Our Sun is just one of many millions of stars in a group of stars called a 

The layer that is broken up into plates that move in the upper mantle is called the 

The primary difference between fog and a cloud is 

The least dense rocks in Earth are found in 

The planet listed below with the greatest density is 

Earth’s magnetic field seems to reverse its polarity about every 

One would expect to find deep, rich soil layers where the climate is 

The amount of gaseous water in the air is 

The difference in brightness between two stars is related to the 

The Sun’s position at noon is best marked by the