What is the electromagnetic spectrum?

In the universe, there are many celestial bodies that emit light and others that reflect it. However, there isn’t only a single type of light, but there are many others of them that our eyes aren’t capable to perceive. With the objective of classifying the different light types, we use the named electromagnetic spectrum.

The light’s energy

The light is, by a definition, a vibration in the fifth dimension. This light is transported by some subatomic particles we name photons. The photons are only capable to transport a determined quantity of energy depending on their type, and this energy is the one that distinguishes the diverse types of light that exist in our universe. The different types of light go from the gamma-rays, the most energetic light, to radio waves, the light with less energy. Apart, the light, depending on its type, can be visible, or invisible. The majority of the light types are invisible to us.

The visible light also presents these energy differences. The visible light contains different colours, starting with the blue colour, to the red colour. According to the light colour, this one contains more energy or less. For example, the blue light is more energetic than the red light. This means that a photon of blue light transports more energy than a red colour photon.

To classify the diverse types of light according to their energy type, we use what we name electromagnetic spectrum, where the different types of light are classified according to their wavelength, or energy, from the most energetic light type to the one that is the less energetic.

An example of the electromagnetic spectrum. In this one, we go from the right (the most energetic light type), to the left, where there is the less energetic type of light.

All the names that we see in the electromagnetic spectrum from the image above, represent the types of light that exist in our universe. As we see, the visible light, the only type of light that we can see with our eyes, only represents a very little part of the spectrum, which is where we can see the colours. The curves that there are on top of the different light types represent the wave-length of each of them. The smallest it is the wavelength, that to say, as more near is a curve from another, the type of light in particular transports more energy. As we see, the gamma-rays are the most energetic of all, while the radio waves have a much bigger wavelength.

The light types

In our universe we know 7 different light types, which are represented in the upper electromagnetic spectrum of the anterior image:

  • At the beginning of the spectrum, where there are the most energetic light types, we see that there are the gamma-rays, followed by the X-rays, those that the doctors use in the medical consultations to do radiographs.
  • Following the X-rays, there is the ultraviolet light. This light, as the majority, isn’t visible to our eyes. The ultraviolet light is responsible for the burns that we make ourselves during the summer due to the extended exposition to the Sun.
  • The visible light is the one that our eyes can analyse, and it is the light with which we perceive the world and that permits us to see colours. As I said, this visible light is formed by different colours, which have different wave-lenºgths between them. The blue light photons transport more energy, while the red light photons transport less of it.
  • Following the visible light, we find the infrared light, that equally as the ultraviolet one, it is responsible for the burns that we make ourselves during the summer.
  • The two last light types are, by order, the microwave waves and the radio waves. These two last types of light are those that carry less energy of all, and, normally, we use them in our everyday lives, for example when we warm up food in the microwaves.

The telescopes

As the light, scientifically named electromagnetic radiation, is the one that brings us the information about the universe, we need devices that are capable of taking it and analyse it. The familiar telescopes are devices that capture mainly visible light. But we have also produced telescopes that can capture invisible light for our eyes, as the gamma-rays, the X-rays, or infrared light. All these telescopes are situated outside the terrestrial atmosphere, as this one absorbs many of these types of light. Precisely, much of the progress in modern astronomy has been produced since humans have been capable of capturing the diverse types of invisible light.

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