Journal of Geophysical Research: Space Physics

The ionosphere is one of the most fascinating parts of Earth’s atmosphere. Formed when solar radiation hits atoms and molecules in the upper atmosphere, stripping their electrons off to produce a plasma, the ionosphere extends from about 40 to 600 miles above the surface of Earth.  As a result of the Sun’s influence, the strength or weakness of the ionosphere depends heavily on the time of day as well as the time of year. The ionosphere on the dayside of Earth, for example, is much more heavily Continue reading >

The thin oxygen atmosphere of Jupiter’s icy moon Europa has been the subject of speculation for over 2 decades, ever since scientists deduced its existence after spotting the telltale glow of ultraviolet auroras.Now, Roth et al. report the results of a 5-month observation campaign by NASA’s Hubble Space Telescope, from late 2014 through spring 2015. By combining that data set with previous Hubble observations as far back as 1999, this study is the most detailed yet of Europa’s auroras.On Earth, Continue reading >

On 27 March 1964, a monster earthquake struck beneath Alaska's Prince William Sound. A 9.2 on the Richter scale, the tremor was the most powerful recorded earthquake in U.S. history. Five months later, a letter published in Nature reported that a magnetometer in the city of Kodiak had recorded disturbances in the Earth's magnetic field just before the quake struck. In the 50-plus years since, several more studies have shown magnetic changes—that they labeled anomalous­—preceding quakes.Such ano Continue reading >

At sunrise or sunset, while it is still dark on the ground, sounding rockets can release small clouds of barium into the upper reaches of the atmosphere. Here, once they are out of Earth’s shadow, these clouds are exposed to the sunlight peeking around the edge of Earth. Sunlight ionizes barium, causing the clouds to feel the forces from Earth’s electric fields.The barium ions move in response to these fields, tracing out the electric currents in the ionosphere. Geomagnetic storms, which increa Continue reading >

Severe space weather can harm satellites, spacecraft, and telecommunications systems on Earth’s surface. Predicting serious events requires a solid understanding of the solar wind, a 1,609,344 kilometer/hour stream of charged particles constantly emitted by the Sun in all directions. However, solar wind dynamics are complex and pose many challenges for the scientists who study them.A new approach by Feng et al. builds and improves on previous efforts to model the solar wind. Driven by real-worl Continue reading >

One of the most mysterious phenomena in all of space physics is magnetic reconnection. This happens when two magnetic fields come into contact and their field lines link up. One example is at the outer edge of the sphere of Earth’s magnetic influence, called the magnetosphere. Here, Earth’s field lines reconnect with the Sun’s magnetic field.Viewed schematically in its simplest form, reconnection takes place within a very wide rectangle; estimates put it at 10 times wider than it is tall. Two f Continue reading >

Magnetospheres are regions of space that are heavily influenced by the magnetic field of a nearby planet, and can contain charged particles in the form of plasma from both external and internal sources. Earth’s magnetosphere, for instance, is filled mostly with particles from the solar wind or, during periods of strong geomagnetic activity, its ionosphere—a region above 85 kilometers in which solar radiation strips molecules of their electrons to produce ions. In the case of Saturn, its moon En Continue reading >

Where does the wind blow? In the Earth’s thermosphere, it’s hard to know.The thermosphere is what most people would refer to as outer space. Beginning at roughly 85 kilometers above the Earth’s surface and extending up to 1000 kilometers, this region is the domain of satellites and space stations. However, even here, there is atmosphere—albeit vanishingly thin. Its temperature reaches 2500°C at times, but, with so few air molecules, you’d hardly feel warm, and, although the wind blows, it carri Continue reading >

Titan is one of the most intriguing moons in the solar system: Not only is it the largest, it’s the only one with a sizeable atmosphere full of aerosols and complex organic molecules—not so dissimilar to the primeval soup from which life emerged on Earth.The chemical reactions that produce this gaseous cocktail begin in the atmosphere’s upper reaches, where the Sun’s ultraviolet rays break molecules apart and strip them of electrons, helping to create the layer of plasma that makes up the ionos Continue reading >

For millennia, humans have cast their gaze to the cosmos and watched in awe as meteors streak across the night sky, leaving behind glowing trails of ionized air and superheated fragments of debris. But in 2014, scientists discovered that the brightest fireball meteors don’t just emit heat and light as they fall through the atmosphere—they also emit radio waves.This discovery came as something of a surprise. Meteors have been known to emit short radio bursts at very low frequencies and also some Continue reading >

What’s old is new again on Mercury—at least when it comes to simulations of the planet’s magnetic field.Like Earth, Mercury has a global magnetic field generated from within the planet that shields it from the Sun’s most powerful rays and particles. It deflects them around the planet to form a roughly teardrop shape, with a round, blunted end facing the Sun and a tail facing away. This boundary of protection is called the magnetopause.However, scientists have gone back and forth on how to model Continue reading >

When solar storms strike Earth, the blast of charged particles causes disturbances in our planet’s magnetic field both in space and on the ground. High above Earth, the oncoming shock waves of particles streaming off of the Sun—called solar wind—distort the planet’s magnetic field lines as they wrap around its nightside, as seen in this video. This can create spectacular auroras around the poles. Meanwhile, on the ground, the Earth’s magnetic field often experiences a spike in intensity in the Continue reading >

Earth has spectacular displays of aurora, the light shows unleashed when solar wind and plasma interact in the atmosphere. When it comes to sheer scale, however, they’ve got nothing on Jupiter, which is the home of the strongest planetary magnetic field in the solar system. Over the past couple of decades, scientists have used both telescopes and satellites to take stunning images of arcs of ultraviolet light shimmering around the gas giant’s poles.Unlike Earth’s aurora, the Jovian auroras are Continue reading >

During Halloween of 2003, it wasn’t the Moon that had space scientists raving—it was the Sun. Erupting with flares from its surface and particles bursting from its outer corona, it unleashed some of the most powerful solar storms ever recorded between October 19 and November 7. At their peak, the Halloween storms of 2003 knocked out power grids in Sweden and caused satellites to fail. Sky gazers reported auroras as far south as Texas and the Mediterranean.The storm even had long-lasting effects Continue reading >

An analysis of the electromagnetic “hiss” that surrounds Earth reveals it’s not just static; there’s a signal hidden within, which may help scientists uncover its source.In space, no one can hear you scream—but if you have the right radio equipment, you can “hear” the electromagnetic waves undulating through the void. Now, scientists have found previously unheard signals in this static that might help them uncover the source of a particular kind of hiss.All of the waves examined in this study w Continue reading >

Saturn is surrounded by a sphere of plasma that rotates in lockstep with the planet, held rigidly in place by its magnetic field. As a result, centrifugal forces tend to fling dense, heavy plasma parcels into deep space. At the same time, less dense material rushes inward to fill their place, forming fingers of hot plasma that penetrate deep inside Saturn’s magnetic field. This shot of plasma is called an interchange injection, and the exact physics of how it occurs remain unknown.But NASA’s Ca Continue reading >

Earth is not the only planet with beautiful aurora displays—Jupiter boasts some of the most powerful in the solar system. Unlike Earth’s, which emit mostly in the visible spectrum, Jupiter’s aurora is mostly in the ultraviolet (UV) part of the spectrum. Over the past 2 decades, NASA’s Hubble Space Telescope has returned some awesome images of the shimmering curtains around the poles of the gas giant. Like Earth’s aurora, Jupiter’s is caused by showers of energetic particles that rain down on th Continue reading >

Earth’s biggest electrical circuit can be found in its atmosphere, where currents flow between the ground and the ionosphere. This global electrical circuit (GEC) gets power from thunderstorms pumping positive charge into the ionosphere—the electrically charged layer of the Earth’s upper atmosphere. This charge gradually returns to the ground during fair weather.Now, Jánský and Pasko have introduced a new model to simulate this process in greater detail while also improving the speed of the sim Continue reading >

Jupiter and Saturn—and other gas giant planets like them in alien solar systems—may have a strange phenomenon related to lightning in their upper atmospheres known as “elves.”This phenomenon was first discovered in the upper reaches of Earth’s atmosphere in the early 1990s. Unlike conventional lightning, which strikes from cloud to cloud or cloud to ground, elves appear high above thunderclouds at the edge of space as an enormous, expanding red ring. First recorded from the Space Shuttle Discov Continue reading >

The boundary of Earth's magnetic field can be a turbulent, chaotic mess. However, a new analysis of decade-old satellite observations is putting Xs and “islands” on the map. These strange magnetic field shapes are a result of the interaction between the magnetic fields of the Earth and the Sun. Drawn schematically, the Earth’s magnetic field is coiled around the planet, with field lines sprouting from the poles, and is swept back into a long tail by the solar wind. Everything might stay simple Continue reading >