After traveling 48 million miles in outer space toward our nearest star, the Solar Orbiter has captured the closest-ever images of the Sun. These breathtaking shots reveal never before seen features on the solar surface.
These images, released Thursday by NASA and the European Space Agency (ESA) mission, are a result of the spacecraft's first close approach to the Sun, which occurred in mid-June. The spacecraft's groundbreaking proximity to the star's surface enabled it to document miniatures solar flares — which scientists have dubbed "campfires."
The spacecraft launched on February 9, 2020, with the Sun as its destination. It's job: Getting up close and personal with our host star in order to resolve some of the lingering mysteries regarding the Sun's magnetic field, solar storms, and how the star affects its surrounding space environment.
The Solar Orbiter travels in an elliptical orbit around the Sun, completing one orbit every 168 days. In mid-June, the spacecraft completed its first perihelion, the point in orbit closest to the Sun, and used its six telescopes to capture the star in unprecedented detail.
After observing the first batch of images, scientists noticed this "campfire" phenomenon. These are believed to be are relatives of solar flares — only a million (or billion) times smaller. Solar flares are fiery eruptions of high-energy radiation that burst from the Sun's surface.
Spotting "campfires" — David Berghmans, a space physicist at the Royal Observatory of Belgium, and principal investigator of one of the instruments onboard Solar Orbiter, was not expecting much from the Solar Orbiter's initial set of data.
"We couldn't believe it when we first saw this and we started giving it crazy names like campfires and dark fibrils and ghosts and whatever we saw," Berghmans said during a press conference on Thursday. "There is so much new small phenomena going on on the smallest scale."
The scientists investigating the images are still not sure whether the "campfires" are driven by the same mechanism as the solar flares or if they are fueled entirely differently. They do think that this newly observed phenomenon may be contributing to one of the Sun's unsolved mysteries — the heating of the Sun's corona.
"We couldn't believe it when we first saw this."
Temperatures of the Sun's core can reach 15 million degrees Celsius. Things get relatively cooler the further you move away from the center of the Sun — it’s a balmy 5,700 degrees C at the solar surface. In the outermost part of the solar atmosphere, known as the corona, temperatures start to rise, reaching more than one million degrees C.
For years, scientists have been looking for an answer to this heating of the corona.
“These campfires are totally insignificant each by themselves, but summing up their effect all over the Sun, they might be the dominant contribution to the heating of the solar corona,” Frédéric Auchère, of the Institut d'Astrophysique Spatiale (IAS), France, and co-principal investigator of the Extreme Ultraviolet Imager, explained during the press conference.
What comes next — Using the Solar Orbiter's Spectral Imaging of the Coronal Environment, or SPICE instrument, scientists will measure the temperatures of these "campfires" in order to help them better understand their origin.
The scientists behind the mission hope to uncover more mysteries of the Sun as the Solar Orbiter continues its journey — it will make its second perihelion in early 2021. A year later, the mission will officially commence its science phase with its first close approach scheduled for early 2022. At that time, the spacecraft will be as close as 26 million miles to the Sun's surface (getting closer to the Sun than the Solar System's innermost planet, Mercury).
The Solar Orbiter joins another spacecraft currently orbiting around the Sun: NASA’s Solar Parker Probe, which launched in August 2018. The Solar Parker Probe will get even closer to the Sun, a record-breaking distance of around 4 million miles from the Sun's surface. But alas, the spacecraft does not carry telescopes that are capable of capturing close-up images of the star — leaving the Solar Orbiter as the only paparazzi covering our favorite star.