The Sun is a massive body of incredibly hot, electrically charged gases (mostly hydrogen). It is held together by an intense internal gravitational pull which creates a powerful pressure inside the Sun. This pressure causes hydrogen atoms to collide with incredible force, forming a new element: helium. This process is called nuclear fusionand he releases a plot of energy. Every 1.5 millionths of a second, the Sun releases more energy than all of humanity could consume in an entire year.
The energy formed by nuclear fusion in the Sun’s core travels downward convective zone then the photosphere, where solar radiation is emitted in the form of charged particles, heat, and light from the sun’s surface and atmosphere. The charged particles create the solar wind which travels far into space, millions of miles away. Heat and light from the sun provide enough energy to sustain the chemical reactions and physical conditions that sustain life on Earth.
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The electromagnetic radiation of the sun
heat, light and radiation that come from the sun are all examples of electromagnetic radiation. Unlike forms of energy that must move through question (like sound), electromagnetic radiation can travel through the vacuum of space, without other atoms, molecules or other particles to carry it. These energy waves are part of the electromagnetic spectrum which encompasses everything from long radio waves to very short gamma rays. Visible light, infrared radiation (heat), and ultraviolet (UV) light are all part of the electromagnetic spectrum.
Radiation on the electromagnetic spectrum has different wavelengths. Wavelengths are measured by the distance between two crests of the wave. The number of peaks that pass a given point in one second is the frequency of the wavelength. The shorter the wavelength, the higher the frequency and the higher the energy. UV light has a shorter wavelength than visible light, which has a shorter wavelength than infrared radiation.
It takes about 8 minutes for electromagnetic radiation from the Sun to travel the 93 million kilometers to Earth. When it arrives, some of this solar energy is blocked or absorbed speak atmosphere, but what is not blocked is absorbed or reflected by the air, soil, water, plants and other matter that covers the surface of our planet. When the molecules of matter gain energy, they move more, vibrate in place or even bounce off each other. You feel it kinetic energy moving molecules like HeatWhere thermal energy.
Unlike electromagnetic radiation, heat must be transferred, or conducted, through matter. Certain types of matter, like water, are really good at holding that energy. Clouds of water particles and gases in the atmosphere also absorb some of this heat. This heat absorption helps the Earth stay warm. It’s one of the reasons our planet stays at a livable temperature and doesn’t change drastically from freezing cold to scorching hot every day.
Most of the solar radiation is in the form of visible light. In the visible light region of the electromagnetic spectrum above, we find the wavelengths for each color of the rainbow. Red light has the longest wavelength and violet the shortest. White light is actually a combination of all colors together. When scientists observe distant stars, they use spectroscopy to split light and analyze colors, much like white light shining through a crystal or prism splits light into a rainbow of different colors. They can use this information to understand the chemical composition, temperature, density, and other information about a star by knowing what colors of light are produced by the combustion of different materials. It’s a way for researchers to study the Sun.
Ultraviolet Light (UV) has a shorter wavelength than visible light and because of this it is invisible to humans. Scientists divide UV light into UV-A, UV-B, and UV-C. Too much of any form of UV light can be harmful to our skin and eyes (UV-C is the most harmful) and can also harm other organisms, including plants. Fortunately, Earth’s atmosphere, including a 22-mile-thick ozone layer stratosphereabsorbs much of this UV light.
Organisms also need UV light. For example, your skin uses UV light to produce vitamin D, a vitamin necessary for strong bones and a healthy immune system. Because too much UV light can be dangerous and abundant on sunny days, it is essential to protect your body from UV exposure when you are in the sun by wearing sunscreen or protective clothing and protecting your eyes with sunglasses.
But how do you know when you’re exposed to UV light? Do you need protection on cloudy days or when it’s raining? What about when you’re indoors, sitting by a window? Do you get the same protection from a t-shirt as from sunscreen?
Let’s find out!