A force of attraction between objects that is due to their masses.

An instrument used to measure temperature

Tiny, one celled organisms found in water that break down organic matter

Non-living factors including temperature, water, sunlight, wind, rocks and soil

Heat transfer by electromagnetic waves

Smallest planet is closest to sun; does not have a true atmosphere; has extreme hot and cold temperatures

A relationship between two organisms of different species where one benefits and the other is neither harmed nor benefited

A structure of calcite skeletons built up by coral animals in warm, shallow ocean water.

Plant food; type of sugar

A series of steps in which organisms transfer energy by eating and being eaten

A phase of the moon that comes after a full moon and before a last quarter moon where all of the moon is lit up except for a small bit on the right side of the moon that we can see.

A frozen mass of different types of ice and dust that orbit the Sun

The curved path of a celestial object or spacecraft around a star, planet, or moon, esp. a periodic elliptical revolution