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The Sun Has Launched A Massive Plasma Attack On Mars

As if the Martian atmosphere was not already thin enough, the impact of this event could strip off even more.


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

The flare on the left side of the Sun caused a coronal mass ejection that will come nowhere near Earth, but is headed for Mars

The flare on the left side of the Sun caused a coronal mass ejection that will come nowhere near Earth, but is headed for Mars.

Image credit: Solar Dynamics Observatory/NASA

The current burst of solar activity has had some noticeable effects on Earth, but just at the moment it’s Mars that is experiencing it the most – or would be if it were populated. Following the spotting of a huge sunspot by the Perseverance rover, a huge coronal mass ejection is expected to make a direct hit on the Red Planet. The fact it is further from the Sun than Earth won’t help much if this occurs, being more than offset by the lack of shielding magnetic field and remaining atmosphere.

Martian auroras are not like those on Earth, with no large magnetic field to channel charged particles from the Sun towards the poles. However, several different sorts of aurora have been seen, including one that stretches halfway across the planet, and whose cause is unknown. Many of these auroras would be invisible to our eyes, but have been picked up with the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile Evolution (MAVEN) mission.


MAVEN and other orbiters will be keeping a close eye out for such events on September 1, when a coronal mass ejection (CME) that left the Sun last weekend is expected to strike. Of less aesthetic value, but more scientific significance, orbiting spacecraft will be looking for evidence the CME has stripped away a little more of the Martian atmosphere, as appears to have happened in association with past auroras. It’s likely events like this represent a big part of the reason Mars has lost its atmosphere, and with it the conditions that allowed it to once have an ocean

We can't see the source of the flare as it is hidden behind the curve of the Sun, but it's rise is easy to detect.
We can't see the source of Saturday's flare as it is hidden behind the curve of the Sun, but it's rise is easy to detect.
Image credit: Solar Dynamics Observatory/NASA

If you look for Mars in the sky at the moment you’ll need a good view west soon after sunset. It’s getting close to being directly on the other side of the Sun from us, which means the side of the Sun facing it is almost completely opposite what we see.

Last week NASA used this geometry to turn Perseverance’s camera towards the Sun and note a massive sunspot we wouldn’t have known about otherwise. It’s not the first time Perseverance has detected sunspots, but this one was large enough to raise suspicion big things were coming by the time the Sun’s rotation turned it Earthward.

Sunspots are the easiest aspect of solar activity to observe, but on their own their significance is small. CMEs, when sections of the Sun’s magnetic field and plasma are ejected into space, are much more important. Although CMEs are usually associated with large sunspots, not every sunspot produces one.


Nevertheless, on August 26, NASA detected an M1 flare rising from part of the Sun currently hidden from our view, but soon to be turned towards us. The area is sufficiently hidden that we can’t see the flare’s source, and according to Perseverance it’s not coming from the previously identified giant sunspot, nor any other Perseverance can resolve.

Like sunspots, not every flare produces a CME, and this one is thought to have been just an M1 class. However, the flare was unusually long-lasting, and it seems that as a result it has triggered a substantial CME, breaking plenty of plasma free of the Sun’s gravity and hurling it into space. 

We’re not always able to predict whether a CME will hit a planet, or slide past, until just beforehand, but in this case a NASA model indicates Mars is in the firing line.

No need to feel neglected, however. Another flare yesterday may have produced an Earth-directed CME, raising prospects for Earthly auroras this weekend.


spaceSpace and PhysicsspaceAstronomy
  • tag
  • Mars,

  • maven,

  • solar activity,

  • plasma,

  • sunspots,

  • coronal mass ejection,

  • sunspot,

  • Astronomy,

  • Perseverance,

  • Martian aurora