Space, Sun and Moon
Science

All the wavelengths or frequencies of electromagnetic radiation
Electromagnetic spectrum
All the wavelengths or frequencies of electromagnetic radiation. Electromagnetic spectrum. The electromagnetic spectrum is the range of all types of light energy, from radio waves to gamma rays, that travel through space.

The two days a year when the Sun is directly over the equator, making day and night equal
Equinox
The two days a year when the Sun is directly over the equator, making day and night equal. Equinox. An equinox occurs when Earth's tilt aligns the equator with the center of the Sun, resulting in equal lengths of day and night globally.

A telescope that uses concave mirrors to reflect and focus light from distant objects
Reflecting telescope
A telescope that uses concave mirrors to reflect and focus light from distant objects. Reflecting telescope. A reflecting telescope is a device that uses mirrors to gather and focus light from stars and planets for viewing.

A device that burns fuel, and expels gas in one direction to move in the opposite direction
Rocket
A device that burns fuel and expels gas in one direction to move in the opposite direction. Rocket. A rocket is a vehicle that moves by pushing gas out one end to propel itself forward, using Newton's third law of motion.