Beyond the aurorae: How solar flares spill out across the Solar System

https://www.bbc.com/future/article/20240702-beyond-the-northern-lights-
how-solar-flares-spill-out-across-the-solar-system

The Sun is extremely active right now, blasting the Earth with the biggest 
solar storms in 20 years. This is what it is doing to the rest of the 
Solar System.

If you happened to look skywards on a few nights in May 2024, there was a 
good chance of seeing something spectacular. For those at relatively low 
latitudes, there was a rare chance to see the flickering red, pink, green 
glow of our planet's aurorae.

A powerful solar storm had sent bursts of charged particles barrelling 
towards Earth and, as they bounced around in our planet's atmosphere, they 
unleashed spectacular displays of the Northern and Southern Lights. The 
dazzling displays of aurora borealis were visible far further south than 
they might normally be – and far further north in the case of aurora 
australis thanks to the power of the geomagnetic storm, the strongest in 
two decades.

Although some people experienced only a faint, eerie glow, others were 
treated to a myriad of colour as far south as London in the UK and Ohio in 
the US. Reports even came in from just to the north of San Francisco, 
California.

But while this spike in activity from the Sun left many on Earth 
transfixed by the light display it produced, it has also had a profound 
effect elsewhere in the Solar System. As most of us wondered at the 
colours dancing across the night's sky, astronomers have been peering far 
beyond to see the strange ways such intense bursts of particles affect 
other planets and the space between them.

"The Sun can fire material outwards in any direction like a garden 
sprinkler," says Jim Wild, a professor of space physics at Lancaster 
University in the UK. "The effects are felt throughout the Solar System."

Our Sun is currently heading towards, or has already reached, its solar 
maximum – the point in an 11-year cycle where it is most active. This 
means the Sun produces more bursts of radiation and particles from solar 
flares and events known as coronal mass ejections (CMEs). If these are 
sprayed in our direction, they can supercharge the Earth's magnetic field, 
causing magnificent aurorae but also posing problems for satellites and 
power grids.

"Things really seem to be picking up right now," says Mathew Owens, a 
space physicist at the University of Reading in the UK. "I think we're 
about at solar maximum now, so we may see more of these kinds of storms in 
the next couple of years."

Around the Sun, multiple spacecraft are observing this increase in 
activity up close. One of those, the European Space Agency's (Esa) Solar 
Orbiter, has been studying the Sun since 2020 on an orbit that takes it 
within the path of Mercury. Currently the spacecraft is "on the far side 
of the Sun as seen from Earth", says Daniel Müller, project scientist for 
the Solar Orbiter mission at Esa in the Netherlands. "So we see everything 
that Earth doesn't see."

The storm that hit Earth in May originated from an active region of solar 
flares and sunspots, bursts of plasma and twisting magnetic fields on the 
Sun's surface, known as its photosphere. Solar Orbiter was able to see 
"several of the flares from this monster active region that rotated out of 
Earth's view", says Müller, bright flashes of light and darkened regions 
called sunspots on the Sun's surface.

One of the goals of Solar Orbiter is "to connect what's happening on the 
Sun to what's happening in the heliosphere," says Müller. The heliosphere 
is a vast bubble of plasma that envelops the Sun and the planets of the 
Solar System as it travels through interstellar space. What Müller and his 
colleagues hope to learn more about is where the solar wind – the constant 
stream of particles spilling out from the Sun across the Solar System – 
"blows into the interstellar medium", he says. "So we are particularly 
interested in anything energetic on the Sun that we can find back in the 
turbulence of the solar wind."

This particular cycle, cycle 25, appears to be "significantly more active 
than what people predicted", says Müller, with the relative sunspot number 
– an index used to measure the activity across the visible surface of the 
Sun – eclipsing what was seen as the peak of the previous solar cycle. The 
National Oceanic and Atmospheric Administration (Noaa) in the US had 
predicted a maximum monthly average of 124 sunspots a day in May, but the 
actual number was 170 on average, with one day exceeding 240, according to 
Müller.

But the exact cause of the Sun's 11-year-long cycle and its variabilities 
remains a bit of a mystery.

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The effects of these changes in solar activity, however, extend far across 
the Solar System. Earth is not the only planet to be hit by solar storms 
as they billow across interplanetary space. Mercury, the closest planet to 
the Sun, has a much weaker magnetic field than Earth – about 100 times 
less – and lacks a substantial atmosphere. But solar activity can cause 
the surface of the planet to glow with X-rays as solar wind rains down. 

Venus also lacks a substantial magnetic field, but the planet does still 
create auroras as the solar wind interacts with the planet's ionosphere.

At Mars, the effect of solar activity is more obvious. Here, a Nasa 
spacecraft called Maven (Mars Atmosphere and Volatile Evolution) has been 
studying the planet's atmosphere from orbit since 2014. "We were on the 
declining side of solar cycle 24 [then]," says Shannon Curry, a planetary 
scientist at the University of Colorado, Boulder in the US and the lead on 
the mission. "We are now coming up on the peak of cycle 25, and this 
latest series of active regions has produced the strongest activity Maven 
has ever seen."

Between 14 and 20 May the spacecraft detected exceptionally powerful solar 
activity reaching Mars, including an X8.7 – solar flares are ranked B, C, 
M, and X in order from weakest to strongest. Results from the event have 
yet to be studied, but Curry noted that a previous X8.2 flare had resulted 
in "a dozen papers" published in scientific journals. Another flare on 20 
May, later estimated to be an even bigger X12, hurled X-rays and gamma 
rays towards Mars before a subsequent coronal mass ejection launched a 
barrage of charged particles in the same direction.

Images beamed back from Nasa's Curiosity Rover on Mars revealed just now 
much energy struck the Martian surface. Streaks and dots caused by charged 
particles hitting the camera's sensors caused the images to "dance with 
snow", according to a press release from Nasa. Maven, meanwhile, captured 
glowing aurora as the particles hit the Mars' atmosphere, engulfing the 
entire planet in an ultraviolet glow.

The entire atmosphere expands dozens of kilometres – exciting for 
scientists but detrimental for spacecraft

The flares can cause the temperature of the Martian atmosphere to 
"dramatically increase," says Curry. "It can even double in the upper 
atmosphere. The atmosphere itself inflates. The entire atmosphere expands 
dozens of kilometres – exciting for scientists but detrimental for 
spacecraft, because when the atmosphere expands there's more drag on the 
spacecraft."

The expanding atmosphere can also cause degradation of the solar panels on 
spacecraft orbiting Mars from the increase in radiation. "The last two 
flares caused more degradation than what a third of a year would typically 
do," says Curry.

Mars, while it has lost most of its magnetic field, still has "crustal 
remnant magnetic fields, little bubbles all over the southern hemisphere", 
says Curry. During a solar event, charged particles can light those up and 
excite particles. "The entire day side lights up in what we call a diffuse 
aurora," says Curry. "The entire sky glows. This would most likely be 
visible to astronauts on the surface."

By the time solar storms reach further out into the solar system, they 
tend to have dissipated but can still have an impact on the planets they 
encounter. Jupiter, Saturn, Uranus, and Neptune all have aurorae that are 
in part driven by charged particles from the Sun interacting with their 
magnetic fields.

But one of the key effects of solar activity on interplanetary space that 
astronomers are eager to study is something called "slow solar wind", a 
more sluggish, but denser stream of charged particles and plasma from the 
Sun. Steph Yardley, a solar astronomer at Northumbria University in the 
UK, says solar wind is "generally classed about 500km/s (310 miles/s)", 
but slow wind falls below this. It also has a lower temperature and tends 
to be more volatile.

Recent work by Yardley and her colleagues, using data from Solar Orbiter, 
suggests that the Sun's atmosphere, its corona, plays a role in the speed 
of the solar wind. Regions where the magnetic field lines, the direction 
of the field and charged particles are "open" – stretching out into space 
without looping back – provide a highway for solar wind to reach high 
speeds. Closed loops over some active regions – where the magnetic field 
lines have no beginning and end – can occasionally snap, producing slow 
solar wind. The variability in the slow solar wind seems to be driven by 
the unpredictable flow of plasma inside the Sun, which makes the magnetic 
field particularly chaotic.

The X-class flares and coronal mass ejections seen in May transformed the 
interplanetary medium as they flung out material across the solar system. 
Solar Orbiter detected a huge spike in ions moving at thousands of 
kilometres per second immediately after the 20 May flare. Computers on 
board other spacecraft – the BepiColombo probe, which is currently on a 
seven-year journey to Mercury, and Mars Express, in orbit around the Red 
Planet – both saw a dramatic increase in the number of memory errors 
caused by the high energy solar particles hitting the memory cells.

The day after the coronal mass ejection, magnetometers on board the Solar 
Orbiter also saw large swings in the magnetic field around the spacecraft 
as a huge bubble of plasma made up of charged particles thrown out from by 
the event washed past it at 1,400km/s (870 miles/s).

Increased solar activity is a boon for scientists. "If you track the 
number of papers produced by solar physicists, you can almost see an 11-
year cycle in there," says Owens. "We are all more scientifically 
productive when there's a lot of activity to study."

As the Sun continues into solar maximum, the Solar System will see more 
and more activity streaming from its surface. Yet while all the planets 
witness at least some of the activity, our planet bears the brunt more 
than most. "Earth is slightly unique in that space weather can have 
interesting effects on human technologies," says Wild. "There's an extra 
dimension here on Earth."

Perhaps one day those anthropogenic effects might be felt elsewhere, too. 
"If you're going to fly to Mars and you have a six-month flight through 
the interplanetary environment, you're going to potentially suck up a lot 
of space weather events," says Wild. "How you protect your astronauts is 
an interplanetary issue that we need to get our heads around."


-- 
We live in a time where intelligent people are being silenced so that 
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Durham Report: The FBI has an integrity problem.  It has none.

No collusion - Special Counsel Robert Swan Mueller III, March 2019.  
Officially made Nancy Pelosi a two-time impeachment loser.

Thank you for cleaning up the disaster of the 2008-2017 Obama / Biden 
fiasco, President Trump.  

Under Barack Obama's leadership, the United States of America became the 
The World According To Garp.  Obama sold out heterosexuals for Hollywood 
queer liberal democrat donors.

President Trump boosted the economy, reduced illegal invasions, appointed 
dozens of judges and three SCOTUS justices.