The Electromagnetic Spectrum
Our universe is rife with waves. Although the term Electromagnetic (EM) Spectrum may seem strange and distant - you’re much more familiar with it then you think! In fact, the spectrum is nothing more than the range of the different types of electromagnetic waves that are possible. Different types of waves are classified by their wavelengths and frequencies - if one changes, so does the other (they are inversely proportional). The longer a wave’s wavelength, the shorter it’s frequency - and thus it is less energetic.
Radio - These have the longest wavelength of anything on the EM Spectrum. These are the types of waves that travel to your radio! However, these types of waves are emitted by many other things, not just your favorite radio station. Stars and gases in space emit these types of waves all the time.
Microwaves - Slightly more energetic than radio waves are microwaves, which yes, are the types of waves in your actual microwave at home! Microwaves are frequently used in Radio Astronomy by studying the natural cosmic radiation in space. Microwaves can be captured and studied by setups like the Very Large Array shown below:
Infrared - Next up is what enables night vision goggles to work! This is also known as thermal vision, because our skin emits infrared radiation! Infrared radiation detection is frequently used in military devices, and it is often used by astronomers to be able to see through thick regions of star dust!
Visible - This aptly named section of the spectrum is the part the humans can see. Every massive (mass containing) object that we can see emits visible radiation. A typical human eye can detect wavelengths of visible light from about 390-750 nm (nanometers). In terms of visible light, red is the least energetic (longest wavelength) and violet is the most energetic!
Ultraviolet - This is one of the types of radiation that the sun emits, and what causes our sunburn! Ultraviolet (UV) is the type of radiation that occurs immediately before violet (ultra-VIOLET), because it has a shorter wavelength - similar to how infrared has a longer wavelength than red light (infra-RED). The hottest objects in the universe usually emit UV radiation. The visible parts of the sun’s radiation is not what burns us - it is the invisible UV radiation.
X-Rays - These are the types of rays that doctor’s use to look at your bones! The man who discovered them, Wilhelm Conrad Röntgen, was awarded the first ever Nobel Prize in Physics for his discovery, in 1901. Very hot gases in the universe also emit harmful X-rays.
Gamma Rays - These rays are the most energetic and powerful waves on the entire spectrum. Radioactive materials can emit gamma rays, and sometimes powerful particle accelerators, like those at CERN, can produce them as well. Only incredible violent and energetic events can emit gamma rays - such as supernovas or the collision of stars and galaxies.