Sun's Poles Unveiled for the First Time by Solar Orbiter, Advancing Insights into Our Cosmic Monarch
5-minute read
Step into the cosmos as we embark on an unprecedented voyage with the Solar Orbiter of the European Space Agency (ESA). For the first time in human history, we've managed to photograph the Sun's elusive south pole, breaking free from Earth's orbit and shedding light on the secrets that have kept scientists on Earth in the dark. This astronomical game-changer offers us a unique opportunity to understand the intricacies of the Sun's magnetic field, solar cycle, and space weather.
The Solar Orbiter's mission? To get up close and personal with the Sun, examining it from previously uncharted angles. Over the last few months, the spacecraft has been meticulously tilting itself to glimpse the solar poles in breathtaking clarity.
Carole Mundell, ESA's scientific director, shares the excitement, declaring, "Today we reveal the first views of the Sun's pole that humanity has obtained—it's like seeing the dark side of the Moon for the first time!" The Sun, our closest celestial neighbor and the life source, also harbors potential threats to modern space and terrestrial energy systems. So understanding its behavior is crucial for navigating the complexities of our cosmic neighbourhood.
Unveiling the Sun's hidden treasure trove
On March 23, the Solar Orbiter reached its initial major inclination and captured a series of never-before-seen images of the Sun's south pole. Just a few days prior, the first high-angle observation campaign took place. These images were painstakingly gathered by three cutting-edge instruments: the Polarimetric and Helioseismic Imager (PHI), the Extreme Ultraviolet Imager (EUI), and the Spectral Imaging of the Coronal Environment (SPICE).
Each instrument contributes a vital piece to the solar puzzle. PHI captures the Sun in visible light and creates detailed maps of its magnetic field. EUI studies the million-degree-hot gas of the solar corona using ultraviolet light. SPICE, the most intricate of the trio, measures the light emitted by various elements like hydrogen, oxygen, or magnesium at different temperatures, showcasing the layered structure of the solar atmosphere.
The Sun is a constant emitter of charged particles, known as solar wind, and occasionally lets loose violent solar storms that can wreak havoc on power grids, satellites, GPS navigation systems, communications, and even commercial flights. Predicting these solar eruptions is essential for maintaining safety on Earth, and understanding the Sun's behaviors can help us do just that.
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A chaotic dance at the south pole
Every 11 years, the Sun experiences an activity cycle that sees it pass through phases of revolution and calm. In the midst of this cycle, its magnetic field reverses, with one pole swapping places with another. This magnetic merry-go-round has a profound impact on the Sun's entire behavior and its effects on Earth. Without direct observations of the solar regions, current models fail to predict the star's most active states with precision.
" Frankly, we didn't anticipate exactly what we'd find with these first observations—the Sun's poles are still largely unknown territories," concedes Professor Sami Solanki of the Max Planck Institute and head of PHI.
One of the first discoveries is that, at the moment the spacecraft captured the images, the Sun's magnetic behavior is unpredictable, with inconsistent north and south magnetic fields overlapping at the south pole. Normally, a magnet presents a well-defined north and south pole, but the current situation is temporary and will only persist during a short period in each solar cycle, during peak activity. This indicates that in about five years, the Sun will reach its next solar minimum, a period of low activity and orderly magnetic behavior.
" Exactly how this order is restored is not yet fully understood, so Solar Orbiter has arrived just in time to observe the entire process," says Solanki.
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SPICE tracks solar wind velocity
The SPICE instrument has successfully measured the speed of the solar wind in a crucial area of the solar atmosphere, the transition region, where temperatures swiftly skyrocket from around 10,000 degrees to hundreds of thousands of degrees.
The SPICE images indicate rapid flows of material, hinting at the existence of tiny solar wind jets. Scientists will analyze this data to determine how these currents form, a breakthrough that could be "a revolution for solar physics," according to the SPICE team's leader from the University of Paris-Saclay, Frédéric Auchère.
A journey just beginning
These first images are simply the beginning of our adventure. The complete set of data from this polar expedition is expected to arrive in October, and over the next few years, the Solar Orbiter will gradually tilt its orbit to reach 33 degrees in 2029. The more the orbit is inclined, the clearer the details of the poles will be. As Müller, the scientist behind the study, put it, "This is just the first step of our staircase to the sky."
This ESA-NASA joint mission marks a historic milestone in solar research. While the Ulysses probe previously flew over the solar poles, it didn't have cameras. Unlike Ulysses, the Solar Orbiter is equipped with telescopes and observes the poles much closer to the star, in addition to studying these phenomena throughout various solar cycle phases. This mission is poised to deliver groundbreaking insights into the mysteries of the Sun, ultimately enhancing our ability to predict and respond to the complexities of solar activity.
The unprecedented images captured by the Solar Orbiter's trio of instruments, including the Polarimetric and Helioseismic Imager (PHI), the Extreme Ultraviolet Imager (EUI), and the Spectral Imaging of the Coronal Environment (SPICE), have unveiled the hidden treasures of the Sun's south pole, offering valuable insights into space-and-astronomy that may help us better understand the average behavior of the Sun and its impact on modern technology. In the coming years, as the Solar Orbiter gradually tilts its orbit to reach 33 degrees, advances in average solar research will be made possible, paving the way for improved predictions and responses to the complexities of solar activity.
