The European Space Agency’s Solar Orbiter spacecraft, or SolO, launched in February 2020, beginning a seven-year mission to intensively study the Sun. It is loaded with 10 different scientific instruments to investigate a multitude of solar phenomena, including things that happen on its surface and the inner corona, and it will help astronomers understand the peculiar mechanisms that go on there.
It has just finished its commissioning phase, where the instruments are switched on and removed after launch. Other spacecraft have approached the Sun (especially NASA’s Parker Solar Probe), but no other mission is so close that it is also equipped with images that look at the sun, capable of taking high-resolution photos of our closest star. .
SolO is not only performing well, it has already started taking data despite not being in its true operational orbit yet. And one thing you find is that solar astronomers are already exciting, because it’s a phenomenon never seen before: tiny bursts of light (well, tiny for the Sun, still terribly powerful on a human scale) have dubbed “bonfires.”
These small-scale explosions were seen across the Sun’s surface. They have never been seen before, in part because they are too small to be clearly seen by other missions. SolO was about 77 million km from the Sun (approximately halfway between Earth and the Sun) on May 30, 2020 when he took these photos. The images were taken with the SolO Extreme Ultraviolet Imager, which from that distance can see details as small as 400 km in diameter on the Sun.
It is unclear what these campfires really are. An exciting possibility is that they are nanoflareslike solar flares but much smaller in scale. Solar flares occur when the Sun’s magnetic field lines get tangled, reconnect with each other (like a gigantic short circuit), and release the energy stored in them. This is a titanic amount of energy; large flares can explode with the energy of thousands of millions nuclear weapons (note that just doing its usual job, the Sun releases around 100 billion megatons* * second power). Happily they don’t happen often.
Nanoflares would work more or less the same way, but it would be a more continuous event, with many of them appearing somewhere in the Sun all the time. They are theoretical, proposed to explain a great solar mystery: why the Sun’s corona is so ridiculously hot.
The surface temperature of the Sun is approximately 5500 ° Celsius. However, above there is an extremely thin gas atmosphere called the corona: it is the beautiful, faint, faint matter you see around the Sun during a total solar eclipse. The strange thing is that the crown is very Hot, reaching temperatures of a million degrees! Usually stars cool down as you move from the core outward, but for some reason once you’re off the surface, things overheat. How?
Many ideas have been debated, but nanoflares are good. If they behave like little solar flares, then making them explode all over the Sun would heat the plasma there and push it away from the surface, heating up the corona tremendously. The problem is that they have never really been seen … but that is why these bonfires seen by SolO are so interesting. If they turn out to be nanoflares, this could solve the mystery of the crown!
At this time it is not possible to say, but other observations, especially with other instruments in SolO, may shed more light (haha) on this.
Of course, SolO is not even in its operational orbit yet. In the next few years, it will pass through Venus twice and Earth once, using its gravity to change its orbit, leaving it even closer to the Sun. On the closest approach, it will be only 43 million km from the Sun and provide even more images. clear. The inclination of the orbit will also change so that the spacecraft can see the poles of the Sun, which are very difficult to observe from Earth. That should be interesting; It reminds me that when Juno flew over Jupiter’s poles, the view was completely different than expected, and all kinds of weird things were seen.
One of SolO’s big goals is to help us better understand how the solar wind also begins. This is the stream of subatomic particles moving away from the Sun with a melody of 1.5 million tons per second, moving away at a speed of 400 kilometers per second and sometimes much more. Like coronal heating, the exact mechanism that the solar wind launches is not well understood, so we hope that SolO (especially combined with observations from other solar observatories) will help clarify that.
Of course, this is not just an academic exercise. The Sun provides us with all the light and heat here on Earth, which I approve of, and would be reason enough to try to understand it better. But the Sun also blows all kinds of fear storms, which also can and have directly affected us on Earth; A major storm can destroy satellites, harm astronauts in orbit, and create widespread power outages that can be remarkably damaging – just read about a storm that very happily missed us in 2012 to get an idea of how bad it can be.
SolO is only just beginning. The nominal mission is to continue looking at the Sun for seven years. That’s a long time, and I hope the data it collects will continue to surprise us.
* *A megaton is the energy equivalent of detonating one million tons of TNT, defined as 4 trillion joules. If you are not familiar with that unit of energy, that hardly matters, because they are many of them and in the end it only means that the Sun is powerfully powerful.
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