• Becca Robinson

No, the Sun is not in "Lockdown" (and other magnetic mysteries)

The Who: Becca Robinson, 29, obvious Michigander, Ph.D. Fellow, Solar physicist by day, ghostwriter by night, wanderer always, and climber sometimes.

The Where: Right now, the Arctic island of Værøy in northern Norway, since we haven't quite integrated back into a "normal" post-COVID life at the Rosseland Centre for Solar Physics in Oslo.

The Coffee: Iced coconut milk latte. Let's go.

I'd like to preface this post by reassuring the reader that, despite what you may have heard over the past week, the Sun hasn't shut itself down just yet.

In reality, I usually don't pay too close attention to pop-science writing because it isn't on my radar during the typical workday. Instead, I'm usually concerned with catching up on scientific articles that span decades, scrolling through datasets relevant to my work, attempting to get my Python script to run properly, and trying not to miss whatever Zoom meetings we have scheduled.

However, a few stories started to pop up last week that caused some of my friends and family to check in with me to make sure we weren't inevitably headed into the next ice age.

So, here's what's going on.

Using language like "lockdown" and describing the Sun's magnetic activity as mostly "blank," one particular badly-written article (that I won't validate with a link) claimed that the Sun's apparent magnetic dip might be signaling a repeat of historical periods known as the Maunder minimum and the Dalton minimum. These minima were periods of quiet Solar magnetic activity that have been correlated with colder-than-usual weather, a brief era known as the "Little Ice Age," and somehow, the eruption of a massive volcano.

I'll skip the lesson on correlation vs. causation, but in short, this is pure fear-mongering.

In reality, the Sun's magnetic field follows a roughly eleven-year cycle, during which it experiences rises and relative dips in magnetic field strength. Historically, one of the best ways to detect this cycle was to look for Sunspots—regions of intense magnetic fields that concentrate in little freckle-patches on the Sun's face or Photosphere. The magnetic field there is so strong that it inhibits heat transfer in those regions, cooling the plasma slightly and making the regions appear dark with respect to the rest of the Sun's face.

Searching directly for Sunspots used to be the best way to trace the Sun's magnetic evolution (and it's not a bad way now), but currently, we can do quite a bit better than that.

Satellites, like Hinode and the Solar Dynamics Observatory, as well as ground-based telescopes, like the Swedish 1-meter Solar Telescope, measure sunlight in a variety of different wavelengths, allowing us to trace light that is particularly affected by the presence of strong magnetic fields. This makes it possible to visualize the Photosphere—the region where Sunspots form—as well as several layers of the Sun's atmosphere; one of which, called the Chromosphere, is shown in the photo below.

My work involves tracing the weaker, ubiquitous "Quiet Sun" magnetic fields in the Photosphere that aren't strong enough to form Sunspots. These are the fields that are present around Sunspots and across the entirety of the Sun's face at all times, and we've only just recently been able to detect them via instruments built to read anomalies in certain spectral lines. So, even if obvious Sunspots aren't present, magnetic fields are still active and evolving on the Sun.

Although the past Solar cycle has been relatively weak, and the Sunspot number has been down, that isn't enough to say that we are definitively headed into another "Little Ice Age." Quite the contrary; if the relatively quiet magnetic fields do result in slightly cooler temperatures, all it will do is offset the warmer weather correlated with our global climate change.

In short: an impending ice age is unlikely, and even though a certain magazine calls itself The Sun, that doesn't mean that it provides accurate information about the actual Sun.

In fact, according to this recent update from the Solar Dynamics Observatory, our favorite star is still alive and kickin'.

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