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Heliophysics Topics

Heliophysics topics are naturally interdisciplinary and offer an engaging way to explore Earth science concepts, as well as demonstrate the fundamentals of physical and life sciences. 

Atmosphere

The atmosphere is a gaseous envelope surrounding and protecting our planet from the intense radiation of the Sun and serves as a key interface between the terrestrial and ocean cycles.

Although it only extends a few hundred kilometers above the surface, it contains a mixture of gases, such as oxygen and nitrogen, that are critical for life to exist. It distributes incoming solar radiation, protecting life from harmful ultraviolet radiation but also driving atmospheric circulation and weather. The atmosphere enables the greenhouse effect, which makes Earth more habitable. Human activity, however, is contributing more gases, many of which are negatively impacting the protective nature of this vital layer. NASA data provide measurements on weather phenomena as well as gases within the troposphere (the lowest layer of the atmosphere) and stratosphere (the layer above the troposphere) and their effect on air quality.

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An illustration showing the layers of Earth's atmosphere.
An illustration of the five different layers of Earth’s atmosphere.
NASA GSFC/Mary Pat Hrybyk-Keith

Geomagnetic Storm

A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth.

Geomagnetic storms result from variations in the solar wind that produces major changes in the currents, plasmas, and fields in Earth’s magnetosphere. The solar wind conditions that are effective for creating geomagnetic storms are sustained (for several to many hours) periods of high-speed solar wind, and most importantly, a southward directed solar wind magnetic field (opposite the direction of Earth’s field) at the dayside of the magnetosphere. This condition is effective for transferring energy from the solar wind into Earth’s magnetosphere.

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Animated image of the aurora glimmering in the night sky, with a LIDAR beam beaming into the sky.
Aurora over Ny-Ålesund, Norway, bisected by a LIDAR beam.
NASA/Joy Ng

Magnetic Fields

The region around a magnetic material or a moving electric charge within which the force of magnetism acts.

Every magnet produces an invisible area of influence around itself. When things made of metal or other magnets come close to this region of space, they feel a pull or a push from the magnet. Scientists call these invisible influences fields. You can make magnetic fields visible to the eye by using iron chips sprinkled on a piece of paper with a magnet underneath. Did you know that the Earth, as well as some other planets, has a magnetic field? There are even magnetic fields on the Sun!

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High-resolution still image of the solar magnetic field showing magnetic field lines in different colors.
High-resolution still image of the solar magnetic field via PFSS – January 1, 2011.
NASA’s Scientific Visualization Studio

Radiation

Radiation is a form of energy that is emitted in the form of rays, electromagnetic waves, and/or particles.

Outside the protective cocoon of the Earth’s atmosphere is a universe full of radiation – it is all around us. Radiation can be created by humans (microwaves, cell phones, radios, light bulbs, diagnostic medical applications such as x-rays) or naturally occurring (the Sun, radioactive elements in the Earth’s crust, radiation trapped in the Earth’s magnetic field, stars, and other astrophysical objects like quasars or galactic centers). In some cases, radiation can be seen (visible light) or felt (infrared radiation), while other forms—like x-rays and gamma rays—are not visible and can only be observed with special equipment. Space radiation is different from the kinds of radiation we experience here on Earth. Space radiation is comprised of atoms in which electrons have been stripped away as the atom accelerated in interstellar space to speeds approaching the speed of light – eventually, only the nucleus of the atom remains.

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Cosmic_Background_Radiation
The full-sky image of the temperature fluctuations (shown as color differences) in the cosmic microwave background, made from nine years of WMAP observations. These are the seeds of galaxies, from a time when the universe was under 400,000 years old.
NASA

Spectroscopy

Spectroscopy is the science of reading light to determine the size, distance, spin and chemical composition of distant objects in space.

Spectroscopy is a complex art – but it can be very useful in helping scientists understand how an object like a black hole, neutron star, or active galaxy is producing light, how fast it is moving, and even what elements it is made of. A spectrum is simply a chart or a graph that shows the intensity of light being emitted over a range of energies. Spectra can be produced for any energy of light – from low-energy radio waves to very high-energy gamma-rays.

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Against a purple background, drawings of a large blue giant star and a small white dwarf are viewed to the left of two rainbow-colored rows representing their spectra. White text along the top reads "Comparing Density Through Spectra."
Differences in the width and clarity of absorption lines of stars can indicate differences in density. The absorption lines of a white dwarf are much broader than those of a blue giant. A white dwarf can be 100,000,000 times denser than a blue giant.
NASA