A spacecraft looping around the Sun made its first close approach – and captured the encounter in glorious detail.
The European Space Agency’s (ESA) solar orbiter entered the close encounter, known as perihelion, on March 26, at a distance of about 48 million kilometers (30 million miles), at the inside the orbit of Mercury.
At this proximity, temperatures reached around 500 degrees Celsius (930 degrees Fahrenheit). Future perihelions are expected to become even closer and warmer.
As it circled its orbit, the spacecraft saw the Sun like we’ve never seen it before – including a fascinating and mysterious feature dubbed a “hedgehog” and detailed views of the usually hidden solar poles.
These new observations, taken with Solar Orbiter’s 10 science instruments working together for the first time, should provide a wealth of data to unravel the behavior of the Sun, including its wild magnetic fields, and the sometimes chaotic weather it casts in interplanetary space.
We’ve already seen a spectacular high-resolution image of the spacecraft as it came up close. Now ESA has released video of the encounter, for a view from a solar probe’s eye of our magnificent star.
Solar Orbiter is about to make a huge difference to solar science, not least because it can show us parts of the Sun that we usually can’t see. For example, due to the view of the Earth orbiting the Sun’s equator, its poles are extremely difficult to study; only spacecraft orbiting above and below the Sun can see these regions.
The polar regions are believed to be extremely important regions for the solar magnetic fields that play such an important role in solar activity. However, since the poles are so hard to see, we don’t know what happens to the magnetic fields there. With its suite of instruments, Solar Orbiter offers unprecedented insight into these enigmatic regions.
His view of the solar south pole on March 30 revealed a seething region of looping magnetic field lines moving away from the Sun.
The solar “hedgehog” is another fascination. It, too, was captured on March 30, and solar physicists have yet to figure out exactly what it is and how it formed. It consists of a relatively small region about 25,000 kilometers in diameter, imaged in extreme ultraviolet light to reveal the activity there.
And what activity: Spikes of hot and cooler solar gases come out in all directions from the solar corona, or atmosphere, like the solar bedhead.
“The images are truly breathtaking” says solar physicist David Berghmans from the Royal Observatory of Belgium.
“Even if Solar Obiter stopped taking data tomorrow, I would be busy for years trying to figure this all out.”
The main purpose of Solar Orbiter is to help scientists understand the effect of the Sun on the entire heliosphere, or the solar sphere of influence defined by the solar wind, the boundary of which extends beyond beyond the orbit of Pluto. This solar wind blows particles and magnetic fields into interplanetary space, tangling with the planets with tangible effects.
The closer Solar Orbiter gets to the Sun, the better it will be able to sample the solar wind blast. As it approached perihelion on March 21, it detected a flow of energetic particles, and even at this distance the detection was telling. The most energetic particles arrived first, followed by the less energetic ones. This suggested that the particles were not produced near Solar Orbiter’s position, but near the Sun’s surface.
Other instruments have picked up solar events that could have produced the particles, accelerating them through space, including a solar flare and coronal mass ejection, not unlike a CME observed by the spacecraft on March 10. , seen below.
The Sun is currently quite active, which means the spacecraft will be beaming home tons of valuable solar activity data. It has at least 14 more perihelions scheduled before 2030, in which it will dive up to 40 million kilometers from the Sun, using Venus rollovers to increase its speed as it circles around.
This first perihelion, so rich in new data and observations, is an enticing foretaste of the solar manna to come.
“We are delighted with the quality of the data from our first perihelion”, says solar physicist Daniel MüllerESA project scientist for Solar Orbiter.
“It’s almost hard to believe this is just the beginning of the mission. We’re going to be really busy.”
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