Scientists Say: Ionosphere | Science News for Students

Scientists Say: Ionosphere

High above the Earth, this thick layer of molecules protects living things on the ground
Nov 20, 2017 — 6:30 am EST
The purple haze surrounding Earth in this artist’s illustration depicts the extent of the ionosphere surrounding our planet. From space, that layer isn’t visible, though.
NASA Goddard Space Flight Center/Duberstein

Ionosphere (noun, “Eye-ON-oh-sphere”)

This is a region of Earth’s upper atmosphere. It spans the area between 75 and 1,000 kilometers (47 and 620 miles) above the planet’s surface. The layer grows and shrinks in response to radiation from the sun. It also absorbs some of that radiation — the type called extreme ultraviolet light. In the ionosphere, ultraviolet light strips electrons from the atoms they are usually bound to. The process is called ionization. That’s how the ionosphere gets its name. And it results in an ionosphere that is full of electrically charged particles.

The ionosphere is useful in many ways. It protects organisms on Earth by absorbing those harmful extreme ultraviolet rays. The electrically charged particles in the ionosphere also reflect some of the waves coming from Earth. In particular, the ionosphere reflects radio waves. It bounces them back toward the ground. This lets radio-users use the ionosphere to send signal long distances, even to the other side of Earth!

In a sentence

Scientists used the August 21, 2016 eclipse to investigate how the ionosphere changes at night.

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Power Words

(more about Power Words)

atmosphere     The envelope of gases surrounding Earth or another planet.

atom     The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

eclipse     This occurs when two celestial bodies line up in space so that one totally or partially obscures the other. In a solar eclipse, the sun, moon and Earth line up in that order. The moon casts its shadow on the Earth. From Earth, it looks like the moon is blocking out the sun. In a lunar eclipse, the three bodies line up in a different order — sun, Earth, moon — and the Earth casts its shadow on the moon, turning the moon a deep red.

electron     A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.

ionosphere     A layer of Earth’s atmosphere lying around 75 and 1,000 kilometers (47 and 620 miles) above Earth’s surface. It absorbs the sun’s harmful extreme-ultraviolet rays. That energy strips electrons from atoms and molecules, creating a zone full of free-floating ions. The share of ions present, here, affects radio and other signals passing through it.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

organism     Any living thing, from elephants and plants to bacteria and other types of single-celled life.

particle     A minute amount of something.

radiation     (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

radio     To send and receive radio waves, or the device that receives these transmissions.

radio waves     Waves in a part of the electromagnetic spectrum. They are a type that people now use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals. They also are used in radar.

sun     The star at the center of Earth’s solar system. It’s an average size star about 26,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.

ultraviolet     A portion of the light spectrum that is close to violet but invisible to the human eye.

ultraviolet light     A type of electromagnetic radiation with a wavelength from 10 nanometers to 380 nanometers. The wavelengths are shorter than that of visible light but longer than X-rays.

wave     A disturbance or variation that travels through space and matter in a regular, oscillating fashion.