FYFD

Tag: aurora

  • Martian Auroras

    Martian Auroras

    Auroras happen when energetic particles — usually from the solar wind — interact with the atmosphere. Here on Earth, they’re most often found near the poles, where our strong global magnetic field converges, funneling particles down from space. Our neighbor Mars has no global magnetic field. Instead, its magnetic field is a hybrid of two sources: 1) induced magnetism from electric currents in the ionosphere and 2) patches of magnetized iron-rich crust. Together, they form an uneven and changeable field that deflects the solar wind less than one Mars radius above the planet’s surface. In contrast, Earth deflects the solar wind about 10-20 Earth radii away.

    Discrete auroras (left panel) occur when electrons plunge down into the atmosphere on magnetic lines coming from Mars’ patchy crust. Global diffuse auroras (center panel) are caused by energetic solar storms that light up the whole atmosphere, sometimes for days at a time. In proton auroras (right panel), incoming solar protons steal electrons from native Martian hydrogen to form high-energy hydrogen atoms that cannot be magnetically deflected. Instead, they penetrate the planet’s bow shock and plunge into the atmosphere, creating a daytime aurora. (Image credit: UAE Space Agency/EMM/EMUS and NASA/MAVEN/IUVS; via Physics Today)

  • The Unusual Auroras of Mars

    The Unusual Auroras of Mars

    Earth, Saturn, and Jupiter have auroras at their poles, generated by the interaction of their global magnetic fields with the solar wind. Mars has no global magnetic field, only remnants of one frozen into areas of its crust; yet it, too, has auroras. Mars’s auroras are rarer and discrete. They occur most often over the southern hemisphere, and researchers now think they know why.

    Four billion years ago, we think Mars had a global magnetic field, much like Earth does. But somehow the planet lost that field. The traces that remain are caught in the minerals of its crust, much like the ancient magnetic fields recorded in areas of the Earth’s sea floor. These magnetized regions of Mars’s crust, shown above as contours in pink and blue, are where the discrete auroras occur.

    Using data from NASA’s MAVEN spacecraft, which orbits Mars, the team discovered a pattern. They found that auroras occur most often when the magnetic lines of the incoming solar wind run antiparallel to the magnetic field lines of the crust. This suggests that the auroras happen as a result of magnetic reconnection, a process where antiparallel magnetic field lines rearrange themselves, releasing energy as a result. Reconnection events provide an opportunity for electrons from the solar wind to accelerate into Mars’s atmosphere, exciting molecules there and generating the auroras. So far we’ve only caught the auroras in UV light, but hopefully one day we’ll see them in visible light as well. (Image credit: R. Lillis et al.; research credit: C. Bowers et al. and B. Johnston et al.; via APS Physics)

  • Icelandic Glow

    Icelandic Glow

    Solar wind particles slam into the atmosphere near Earth’s poles, creating billowing curtains of glowing plasma known as auroras. Beneath the earth, molten rock seethes and flows, squeezed up fissures to release explosive gases and spurts of lava to the surface world. These natural phenomena are captured in the left and center of this image, respectively. To the right, three plumes of water vapor rise from a geothermal power plant. Three very different phenomena — all fluid dynamical in nature and all captured in a single image of Iceland. It’s no wonder the island is covered in tourists. (Image credit: W. Gorecka; via APOD)

  • “Emerald Roots”

    “Emerald Roots”

    As charged particles from the solar wind bombard the upper atmosphere, a glowing plasma forms and dances in the sky. The green light of the plasma reflects off moistened sand, rippled by the passage of wind and tide. Each component seems simple, but this striking image contains hidden depths of fluid dynamics. Magnetohydrodynamics govern the aurora’s dance; the sand’s self-organization mirrors dune physics; and even the rocky outcropping in the background was carefully shaped by erosive forces from wind and water. Truly, fluid dynamics are found everywhere. (Image credit: L. Tenti; via 2023 Astronomy POTY)

  • Vivid Auroras Over Iceland

    Vivid Auroras Over Iceland

    When solar storms in late February sent energetic particles toward Earth, photographer Cari Letelier ventured to the remote northern edge of Iceland to capture the resulting auroras. When fast-moving, high-energy particles from the solar wind meet Earth’s magnetosphere, they’re directed toward the poles. There the particles slam into Earth’s upper atmosphere, exciting atoms that glow in greens, reds, and pinks. Curtains of light dance across the sky as a result. February’s show was particularly stunning, as captured by Letelier at Arctic Henge. (Image credit: C. Letelier; via Colossal)

  • Jupiter in Infrared

    Jupiter in Infrared

    These recent composite images from the James Webb Space Telescope show Jupiter in stunning infrared detail. They’re the result of several images taken in different infrared bands, then combined and rendered in visible light. In general, the redder colors show longer wavelengths and the bluer ones show shorter wavelengths.

    Jupiter’s cloud bands appear in beautiful detail. The Great Red Spot looks white in infrared. And the planet’s polar auroras shine bright in both images. The wide-angle shot additionally shows two of Jupiter’s moons and the planet’s rings, which are a million times fainter than the planet itself. If you look carefully, you may also see faint points of light in the lower half of the image. These are likely distant galaxies “photobombing” Jupiter’s close-up. (Image credit: NASA/ESA/Jupiter ERS Team 1, 2; via Colossal)

    This composite image of Jupiter was taken in infrared bands and rendered into visible light. In general, the redder colors represent longer wavelengths and bluer ones shorter wavelengths.
    This composite image of Jupiter was taken in infrared bands and rendered into visible light. In general, the redder colors represent longer wavelengths and bluer ones shorter wavelengths.
  • Brilliant Auroras

    Brilliant Auroras

    Glowing auroras billow across Canada in this satellite image from a recent geomagnetic storm. As our sun enters a more active part of its solar cycle, we can expect more space weather as the high-energy particles of the solar wind interact with our planet’s magnetic field. The auroras themselves are light released by energetically excited atoms of oxygen and nitrogen high in the upper atmosphere.

    Earth is not the only place in the solar system to experience these light shows. With their strong magnetic fields, Jupiter and Saturn have auroras that make Earth’s look paltry in comparison. (Image credit: J. Stevens; via NASA Earth Observatory)

  • Jovian Auroras

    Jovian Auroras

    Like Earth, Jupiter is home to polar auroras that light the sky as charged particles interact with the planet’s magnetosphere. A recent paper identifies interesting features in the aurora that appear similar to expanding vortex rings (see inset below). Although the researchers cannot yet identify the origin of the rings, they hypothesize that the process begins at the far edges of Jupiter’s magnetosphere where it interacts with the incoming solar wind. One theory posits that shear flows and Kelvin-Helmholtz instabilities where the magnetosphere and solar wind meet drive the phenomenon. (Image credit: Jupiter – NASA, ESA, and J. Nichols, aurora features – NASA/SWRI/JPL-Caltech/SwRI/V. Hue/G. R. Gladstone/B. Bonfond; research credit: V. Hue et al.; via Gizmodo)

    Diagram showing an inset of Jupiter's northern aurora, with further insets showing the expanding ring features.
  • Grayscale Aurora

    Grayscale Aurora

    This swirling grayscale image shows a spring aurora over the Hudson Bay, as seen by the Suomi NPP satellite. As energetic particles from the sun zip past Earth, they interact with our magnetosphere, which tends to channel particles toward the poles. At these higher latitudes, some of the particles get trapped along Earth’s magnetic field lines and crash into the upper atmosphere where they excite oxygen and nitrogen molecules. It’s this molecular bombardment that creates the distinctive colors of the aurora. (Image credit: J. Stevens; via NASA Earth Observatory)

  • Featured Video Play Icon

    “The World Below”

    Since the first cosmonauts and astronauts entered orbit around our planet, they’ve held a unique perspective. Thanks to the timelapse photography of recent astronauts aboard the ISS and the editing skills of photographer Bruce W. Berry, Jr, the rest of us can enjoy a taste of that viewpoint. Turn up the volume, fire up the big screen, and enjoy.

    I particularly like how several of the sequences show off the depth of the atmosphere. Earth’s atmosphere is incredibly thin compared to the size of our planet – less than one percent of Earth’s radius – but thanks to the shadows that clouds cast on one another, you can really appreciate their height in sequences like the one at 2:26. (Video credit: B. Berry, Jr. using NASA footage)