() – New images of the Sun captured by the Solar Orbiter mission reveal the highest-resolution views of our star’s visible surface obtained to date, revealing sunspots and a constantly moving charged gas called plasma. The images could provide heliophysicists with new clues that will help unlock the secrets of the Sun like never before.
The images, taken on March 22, 2023, and released on Wednesday, show different dynamic aspects of the Sun, including the movements of its magnetic field and the glow of the ultra-hot solar corona, or outer atmosphere.
The spacecraft used two of its six imaging instruments, the Extreme Ultraviolet Imager (EUI) and the Polarimetric and Helioseismic Imager (PHI), to capture the images from 74 million kilometers away.
Solar Orbiter, a joint mission of the European Space Agency and NASA that launched in February 2020, orbits the Sun from an average distance of 42 million kilometers. Missions like Solar Orbiter and NASA’s Parker Solar probe are helping answer key questions about the golden orb, such as what powers its stream of charged particles called the solar wind and why the corona is so much hotter than the sun’s surface.
The Parker Solar probe is about to make the closest approach to the Sun attempted by a spacecraft at the end of December, while Solar Orbiter will be responsible for taking the closest images of the solar surface in history. The Parker Solar probe’s flight path will take it too close to the Sun to carry cameras and telescopes, but the Solar Orbiter is equipped with an array of instruments to share its unique observations of the Sun.
Additionally, Solar Orbiter and the Parker Solar probe study the Sun at close range at an ideal time: during the peak of its annual cycle.
“The Sun’s magnetic field is key to understanding the dynamic nature of our star, from the smallest to the largest scale,” says Daniel Müller, Solar Orbiter project scientist, in a statement.
“These new high-resolution maps from Solar Orbiter’s PHI instrument show the beauty of the Sun’s surface magnetic field and its flows in great detail. At the same time, they are crucial for inferring the magnetic field in the Sun’s hot corona, which our EUI instrument is imaging.”
Together, the new images show the varied and complex layers of the Sun.
The Polarimetric and Helioseismic Imager (PHI) instrument took the highest-resolution comprehensive images of the Sun’s visible surface, or photosphere, to date. Almost all solar radiation comes from the photosphere, whose temperatures range between 4,500 and 6,000 °C (8,132 and 10,832 °F).
Beneath the photosphere layer is hot plasma moving in the Sun’s convection zone, similar to how hot magma moves in the Earth’s mantle.
The goal of the PHI instrument is to map the brightness of the photosphere and measure the speed and direction of the Sun’s magnetic fields.
The visible light image of the photosphere shows sunspots, which resemble holes in the solar surface. These dark regions, some of which can reach the size of Earth or more, are driven by the sun’s strong, constantly changing magnetic fields. Spots, regions where the Sun’s magnetic field passes through the surface, are colder than their surroundings and emit less light.
The PHI instrument also allowed scientists to take a magnetic map, or magnetogram, showing the concentrations of the Sun’s magnetic field within its sunspot regions. Normally, convection helps move heat from the Sun’s interior to the Sun’s surface, but this process is disrupted when charged particles are forced to follow magnetic field lines that cluster around sunspots.
The scientists also measured the speed and direction of material on the solar surface using a velocity map or “shorthand.” The blue parts indicate movement toward the Solar Orbiter, while the red parts show movement away from the spacecraft.
Typically, charged gas on the Sun’s surface moves parallel to the Sun’s rotation on its axis, while plasma moves around sunspots.
For its part, the Extreme Ultraviolet Imager (EUI) observes the solar corona to help determine why it is so much hotter than the photosphere, reaching 1.8 million °F (1 million °C). The EUI image of the corona provides a snapshot of what is happening above the photosphere, and hot, bright plasma can be seen protruding from sunspot regions.
Given Solar Orbiter’s proximity to the sun, the spacecraft had to be rotated after each image to capture every part of the sun’s face. As a result, each image is the result of a mosaic of 25 individual images.
Mark Miesch, a research scientist at the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center, acknowledged that both large-scale features, such as solar magnetism, and small-scale surface features can be seen in the images. . Miesch was not involved in the publication of the images.
“The closer we look, the more we observe,” said Miesch, who is also a research scientist at the University of Colorado Cooperative Research Institute in Environmental Sciences. “To understand the complex interplay between big and small, between twisted magnetic fields and churning flows, we need to see the Sun in all its splendor. These high-resolution images from Solar Orbiter bring us closer than ever to that aspiration.”
Scientists from NOAA, NASA and the International Solar Cycle Prediction Panel announced in October that the sun reached solar maximumor peak of activity within its 11-year cycle. At the peak of the solar cycle, the Sun’s magnetic poles change position, causing the Sun to go from calm to activity. Experts record the increase in solar activity by counting the number of sunspots that appear on its surface. The Sun is expected to remain active during the next year.
“This announcement does not mean that this is the peak of solar activity that we will see this solar cycle,” Elsayed Talaat, director of space weather observations at NOAA, said at a press conference in October. “Although the sun has reached the period of solar maximum, the month in which solar activity peaks will not be identified for months or years.”
Solar activity, including flares or coronal mass ejections, creates space weather that impacts Earth. Coronal mass ejections are large clouds of ionized gas called plasma and magnetic fields that erupt from the sun’s outer atmosphere. Solar storms can affect power grids, GPS and aviation, as well as satellites in low Earth orbit. Storm activity also causes radio blackouts and even poses a risk to manned space missions.
Storms are also responsible for generating auroras that dance around the Earth’s poles, known as the aurora borealis and australis. When energized particles from coronal mass ejections reach Earth’s magnetic field, they interact with gases in the atmosphere to create different colored lights in the sky.
On December 24, the Parker Solar probe will approach within 6.2 million kilometers of the solar surface, the closest approach to the Sun of any human-made object. The flyby could help scientists study the origins of space weather right at the source, as the probe will get close enough to navigate through plasma plumes and solar flares connected to the sun.
Add Comment