How many fundamental forces are known in science?

The cause of the Mariana Trench on the west coast of the United States is

Why does the Earth have seasons?

Lenticular galaxies are similar in structure to a spiral galaxy. Which feature are they missing?

There is star formation in Elliptical Galaxies.

The absolute magnitude of a star is defined to be the apparent magnitude that the star would have if it were at a standard distance of _____ parsec(s).

What percentage of visible matter is made of Hydrogen?

The method used by Hubble to determine the distance to the Andromeda galaxy was

Which of the following is evidence supporting the Big Bang model?

The planet that has a rotation period longer than its year is