Fall into our nearest star in this gorgeous high-resolution view of the Sun. Taken by Solar Orbiter, a joint NASA-ESA mission, the image stretches from the fiery photosphere — full of filaments and prominences — to the wispy yet unbelievably hot corona. It’s well worth clicking through to zoom in and around the full size image. (Image credit: ESA & NASA/Solar Orbiter/EUI Team, E. Kraaikamp; via Gizmodo)
Tag: sun
Striations on the Sun
One of the perpetual challenges for fluid dynamicists is the large range of scales we often have to consider. For something like a cloud, that means tracking not only the kilometer-size scale of the cloud, but the large eddies that are about 100 meters across and smaller ones all the way down to the scale of millimeters. In turbulent flows, all of these scales matter. That problem is even harder for something like the Sun, where the sizes range from hundreds of thousands of kilometers down to only a few kilometers.
It’s those fine-scale features that we see captured here. This colorized image shows light and dark striations on solar granules. Scientists estimate that each one is between 20 and 50 kilometers wide. They’re reflections of the small-scale structure of the Sun’s magnetic field as it shapes the star’s hot, conductive plasma. (Image credit: NSF/NSO/AURA; research credit: D. Kuridze et al.; via Gizmodo)
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Seeing the Sun’s South Pole For the First Time
The ESA-led Solar Orbiter recently used a Venus flyby to lift itself out of the ecliptic — the equatorial plane of the Sun where Earth sits. This maneuver offers us the first-ever glimpse of the Sun’s south pole, a region that’s not visible from the ecliptic plane. A close-up view of plasma rising off the pole is shown above, and the video below has even more.
Solar Orbiter will get even better views of the Sun’s poles in the coming months, perfect for watching what goes on as the Sun’s 11-year-solar-cycle approaches its maximum. During this time, the Sun’s magnetic poles will flip their polarity; already Solar Orbiter’s instruments show that the south pole contains pockets of both positive and negative magnetic polarity — a messy state that’s likely a precursor to the big flip. (Image and video credit: ESA & NASA/Solar Orbiter/EUI Team, D. Berghmans (ROB) & ESA/Royal Observatory of Belgium; via Gizmodo)
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The Solar Corona in Detail
The sun’s corona — its outer atmosphere — is usually impossible to see, since it’s far outshone by the rest of the sun. But during a total solar eclipse, the moon blocks out all but the vibrant, wispy corona. Getting a detailed image of the corona is tough; it’s constantly shifting. For this image, engineer Phil Hart used 5 main cameras, 4 refractors, 2 laptops, and plenty of digital image processing to capture some incredible details of the plasma and hot gases dancing along the sun’s magnetic field lines. You can learn about the awesome effort behind this image — and see more awesome photos from the eclipse — at his site. (Image credit: P. Hart; via APOD)
Solar Filament Eruption
From Earth, we rarely glimpse the violent flows of our home star. Here, a filament erupts from the photosphere creating a coronal mass ejection, captured in ultraviolet wavelengths by the Solar Dynamics Observatory. This particular eruption took place in 2012, and, while it was not aimed at the Earth, it did create auroras here a few days later. Eruptions like these occur as complex interactions between the sun’s hot, ionized plasma and its magnetic fields. Magnetohydrodynamics like these are particularly tough to understand because they combine magnetic physics, chemistry, and flow. (Image credit: NASA/GSFC/SDO; via APOD)
A Shallow Origin for the Sun’s Magnetic Field
The Sun‘s complex magnetic field drives its 11-year solar activity cycle in ways we have yet to understand. During active periods, more sunspots appear, along with roiling flows within the Sun that scientists track through helioseismology. Longstanding theories posit that the Sun’s magnetic field has a deep origin, about 210,000 kilometers below the surface. But new measurements have prompted an alternate theory: that the Sun’s magnetic field originates in its outer 5-10% due to a magnetorotational instability.
Magnetorotational instabilities are usually associated with the accretion disks around black holes and other massive objects. When an electrically-conductive fluid — like the Sun’s plasma — is rotating, even a small deviation in its path can get magnified by a magnetic field. In accretion disks, these little disruptions grow until the disk becomes turbulent.
By applying this idea to the sun, researchers found they were better able to match measurements of the plasma flows beneath the Sun’s surface. With measurements from future heliophysics missions, they believe they can work out the mechanisms driving sunspot formation, which would help us better predict solar storms that can damage electronics here on Earth. (Image credit: NASA/SDO/AIA/LMSAL; research credit: G. Vasil et al.; via Physics World)
The Solar Corona in Stunning Detail
The ESA’s Solar Orbiter captured this beautifully detailed video of our sun‘s corona last September. The Solar Orbiter took this footage from about 43 million kilometers away, a third of the distance between the sun and the Earth. Scattered across the visible surface are fluffy, lace-like features known as coronal moss. Along the curving horizon, gas spires called spicules stretch up to heights of 10,000 kilometers. The video also highlights a “small” eruption of plasma that is nevertheless larger than the entire Earth. We can even see evidence of coronal rain, denser and darker clumps of plasma that gravity pulls back toward the sun. (Video and image credit: ESA; via Colossal)
Our Sun’s Corona Unfurled
This clever image is actually two solar eclipses stacked atop one another. The bottom half of the image shows the sun‘s corona — its wispy, dramatic outer atmosphere — during the a 2017 total solar eclipse, and top half shows a 2023 total solar eclipse. In both, the corona has been unwrapped from around the sun’s circumference and project instead into a rectangle.
The 2017 eclipse took place near the minimum of the sun’s solar cycle and appears relatively tranquil. The 2023 eclipse, in contrast, came near solar cycle’s maximum and shows a far more chaotic and turbulent environment. Notice the bright pink solar prominences dotting the mid-line and the field of shadowy plasma loops above them. (Image credit: P. Ward; via APOD)
“A Sun Question”
The sun‘s surface and atmosphere are endlessly dynamic, with magnetic lines, plasma, and convection creating a constant churn. In this photo by astrophotographer Eduardo Schaberger Poupeau, a curving question-mark-like filament appears above the sun’s surface. Even with decades of high-resolution data from recent solar probes, we struggle to understand the complex physics that feed structures like these. (Image credit: E. Poupeau; via 2023 Astronomy POTY)
Solar Coronal Heating
Our Sun‘s visible surface, the photosphere, is about 5800 Kelvin, but the temperature of the wispy corona is far hotter, reaching a million Kelvin in some places. Why the corona is so hot remains something of a mystery. Scientists have theorized multiple culprits for the extreme temperatures found in the corona, but the full details of the phenomenon are still unclear.
Recent solar missions and observations are increasingly identifying small but widespread solar activities, like the nanoflares shown above. Unlike the monstrous coronal loops researchers focused on previously, these flares are tiny and occur in regions without discernible solar flare activity. The nanoflares are brief but they can reach temperatures above a million Kelvin. Since nano- and even picoflares have been observed across the full Sun, they likely play a significant role in the overall picture of coronal heating. (Image credit: ISAS/JAXA; see also L. Sigalotti and F. Cruz)
