What waves does sun produce?

Almost all of the energy available at Earth’s surface comes from the sun. The sun gets its energy from the process of nuclear fusion. This process occurs in the sun’s core or interior, where temperature and pressure are extremely high. During most of the sun’s life, energy comes from the fusion of hydrogen nuclei. In this process (explained simply), four hydrogen nuclei are fused, forming a helium nucleus. Energy is released because the helium nucleus has a slightly lower mass than the four original hydrogen nuclei. Einstein’s famous formula (E = mc2 or Energy = mass × the speed of light squared) explains why energy is released. This energy eventually makes its way to the outer regions of the sun and is radiated or emitted away in the form of energy, known as electromagnetic radiation. A particle of electromagnetic radiation is known as a photon. Electromagnetic radiation, also known as radiant energy (or radiation), is spread in the form of electromagnetic waves.

Electromagnetic waves are waves that can cause charged particles (such as electrons) to move up and down. These waves have both electrical and magnetic properties and can travel through gases, liquids, solids, and through empty space (or a vacuum) at nearly 300,000 kilometers per second (the speed of light).

Electromagnetic waves are characterized by wavelength and frequency. The wavelength is the distance between two wave crests or troughs. The highest point of a wave is called the crest, and the lowest point of a wave is called the trough. Frequency is expressed in hertz (Hz) and refers to the number of wavelengths that pass a fixed point in 1 second. The shorter the wavelength is, the higher its frequency will be. The reverse is also true. For example, radio waves have the longest wavelength and the lowest frequency.

Electromagnetic Spectrum

The electromagnetic spectrum represents the complete range of electromagnetic radiation. The region of the spectrum with a shorter wavelength than the color violet is referred as ultraviolet radiation, and the region of the spectrum with a longer wavelength than the color red is referred to as infrared radiation.

The Sun’s Electromagnetic Spectrum

The energy that reaches the Earth is known as solar radiation. Although the sun emits radiation at all wavelengths, approximately 44% falls within visible-light wavelengths. The region of the spectrum referred to as visible light (light our eyes can detect) is composed of
relatively short wavelengths in the range 400 nanometers (nm), or 0.4 micrometers (μm), through 700 nm, or 0.7 μm.

When you hear the word "light," what comes to mind? For most people, the answer is sunlight. The sun constantly emits light.

Light continuously reaches the earth from the sun. You might also say, "The sun sends electromagnetic energy as light." The electromagnetic waves emitted by the sun are of a broad spectrum ranging from X-rays with a wavelength of 2 nanometers to radio waves with a wavelength of 10 meters. The most intense of these to reach the earth's surface is visible light, with a wavelength around 500 nanometers.

The energy the earth receives from the sun is called the "solar constant," which is defined as 2 calories per square centimeter per minute. Based on meters squared, the solar constant is equivalent to 1.4 kilowatts, or one electric heater. The energy reaching the earth's surface is less than this value, owing to such factors as atmospheric absorption, but the sun is nevertheless a major source of energy for the earth.

Asked by: Karen Olsen, Leicester

The Sun emits radiation right across the electromagnetic spectrum, from extremely high-energy X-rays to ultra-long-wavelength radio waves, and everything in-between. The peak of this emission occurs in the visible portion of the spectrum.

Different wavelengths of light generally come from different regions of the Sun’s atmosphere or are due to particular atoms radiating at specific wavelengths (spectral emission lines). Visible light, for example, comes from the photosphere (or surface) whereas most infrared light comes from the lower chromosphere just above. Much of the high-energy UV and X-ray photons come from the Sun’s outer atmosphere (called the corona). This gives astronomers the ability to explore different solar features, constituents or processes simply by selecting a particular wavelength of light to observe. That is why NASA’s Solar Dynamics Observatory, for example, has an array of instruments that cover a wide range of wavelengths simultaneously.

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