A Rainy Day on the Sun

Hello, friends!

I was recently introduced to a new song by Jean Grae entitled “Stop Drawing Sunglasses on the Sun” (click here).  The song raises some valid points.  As an artist who frequently draws sunglasses on the Sun, I guess I have some soul-searching to do.

In the meantime, I recently saw a report on spaceweather.com that said it was raining on the Sun.  So naturally, I drew this:

Pretty much everything associated with the Sun it extremely big, extremely hot, and relates somehow to the Sun’s extremely powerful magnetic field.  The Sun’s coronal rain (no relation to the coronavirus) is no exception.

First, let’s talk about the role of the magnetic field.  Ionized gas (a.k.a. plasma) rides up the Sun’s magnetic field lines to form solar prominences: those arch-like or loop-like structures that are often seen suspended above the Sun’s surface.

These prominences are extremely hot, at least by Earth standards, but they’re not quite as hot as the Sun’s surface.  According to this paper from Astrophysical Journal Letters, there are at least two possible explanations for how solar prominences loose their heat.  Whatever the cause of the heat loss, the result is that the cooling plasma begins to condense, much as cooling water vapor condenses in Earth’s atmosphere.  And then rain drops start to form.

But of course, these rain drops are extremely big, more like “rain blobs.”  Due to the technical limitations of Earth-based and space-based solar observatories, we can’t say for sure how big these rain blobs get, but some appear to be “on the order of 5000 km in radius,” according to that same paper from Astrophysical Journal Letters.

So in summation, it rains on the Sun.  Seriously, it rains a lot!  And like pretty much everything else relating to the Sun, this coronal rain is extremely big, extremely hot (by Earth standards), and is associated with the Sun’s extremely powerful magnetic field.  So maybe the Sun doesn’t need sunglasses, but an umbrella seems appropriate.

Next time on Planet Pailly, what is so super about a supermoon?