Month: July 2025

ULTRAVIOLET (UV) LIGHT
Electromagnetic radiation with wavelengths shorter than visible light, harmful in large doses.

VISIBLE LIGHT
The small portion of the electromagnetic spectrum that can be seen by the human eye.

INFRARED RADIATION
Heat energy emitted by objects, used in infrared astronomy.

MICROWAVES
Electromagnetic waves with shorter wavelengths than radio waves, used in radar and satellite communication.

RADIO WAVES
The longest-wavelength electromagnetic waves, used in communication and radio astronomy.

ELECTROMAGNETIC SPECTRUM
The range of all types of electromagnetic radiation, from radio waves to gamma rays.

GREGORIAN CALENDAR
The modern calendar, introduced by Pope Gregory XIII in 1582, based on the solar year.

JULIAN CALENDAR
A calendar introduced by Julius Caesar, later replaced by the Gregorian calendar.

UNIVERSAL TIME (UT)
A time standard based on Earth’s rotation, used in astronomy and navigation.