A device that converts natural energy into useful work is called an engine. Contact force is the force of attraction between any two objects. Matter is anything that takes up space and has mass and weight. Friction is the force that resists motion between surfaces. Light energy is the energy we can see. Chemical energy is stored in chemical bonds, and kinetic energy is energy of motion. Liquid becomes gas at the boiling point of a substance. The boiling point and condensation point of water is 100°C. Ice is lighter than water because it is less dense.
The chromosphere is the sun's atmosphere. Lunar eclipses happen when the moon passes through Earth's shadow. The troposphere is the layer of the atmosphere that is closest to the Earth. The ozone layer is the layer that protects Earth from ultraviolet rays. 21% of air is oxygen. 93,000,000 mi is the distance of the sun from Earth. In the mesosphere, meteoroids burn up.
Crescent is the first moon phase after a new moon. Mercury is the planet closest to the sun. Venus is known as Earth’s bright twin but is inhospitable. Jupiter is the largest planet and the 5th from the sun. Saturn has seven rings and is three planets away from Earth. Uranus lies on its side and has 27 moons. Neptune is the last planet in the solar system and has fast winds. Mars is a red one shining bright in the night.
A scientist who studies weather is a meteorologist. Rising air, water vapor, and dust are the three ingredients to form clouds. Sea fog is the fog that forms over oceans. Altocumulus cloud is bumpy and white and floats at medium height. Cumulonimbus is the cloud type that produces thunder, rain, and hail.