Sometimes it Rains on the Sun

(Updated post from 2013)

The Sun is awesome. I mean, never mind that it contains 99% of all the mass in the Solar System, that it supplies our planet with the energy needed to sustain life, that its constantly-blowing solar wind helps keep some of those nasty cosmic particles out of the planetary neighborhood, and that it makes a bright sunshiny day on Earth possible (but remember to wear sunscreen!) In addition to all that, it’s also just really, really cool. In the hot sense, of course.

But even on the Sun a little rain must fall…just not like it does here.

Watch the video above from NASA’s Solar Dynamics Observatory (SDO) and you’ll see what I mean.

Back on July 19, 2012, during the height of the last solar maximum, SDO captured a looping prominence on the Sun that could dwarf our planet. It rose up from the Sun’s eastern limb after a flare and resulting coronal mass ejection, or CME, forming an arc of solar plasma that grew bright in extreme ultraviolet light but then began to “rain” back down to the surface, a phenomenon known as coronal rain.

It’s not fire, it’s not lava, it’s not even a liquid, yet on those scales and with that sort of magnetic energy controlling it the behavior of the solar material is truly mesmerizing to watch.

For an idea of timing, each second in the video above corresponds to 6 minutes of real time.

Magnetic fields, themselves, are invisible, but the charged plasma is forced to move along the lines, showing up brightly in the extreme ultraviolet wavelength of 304 Angstroms, which highlights material at a temperature of about 50,000 Kelvin. This plasma acts as a tracer, helping scientists watch the dance of magnetic fields on the sun, outlining the fields as it slowly falls back to the solar surface.
(Source: NASA)

Also, contrary to popular belief the Sun is not a ball of fire. Fire is a chemical process of rapid oxidation—there’s no oxidation occurring on or in the Sun. There’s nothing actually “on fire” (unlike a burning log in a campfire.) All those loops and tongues of “flame” and dancing flickers you see are the result of magnetic activity, arcs of magnetic fields that rise up through the Sun’s “surface” (that is, photosphere) and carry superheated, glowing plasma along with them, making the magnetic fields visible to SDO’s instruments.

Scale of Earth to Sun Aug 21 2017
Scale size of Earth and the Moon compared to the Sun.

Compared to Earth the Sun is enormous — 880,000 miles / 1.41 million kilometers in diameter, it’s a sphere big enough to contain over a million Earths — and its magnetic fields are powerful and complex. They rise and fall like ocean waves across its surface, but also can create graceful arcs and twisting tornadoes that extend tens of thousands, sometimes hundreds of thousands of miles out into space.

What’s even more amazing to think about is that this isn’t just our Sun that’s acting this way — this is a star we’re looking at here, and as such this is how stars behave. The points of light in the night sky, they all do this too… just very far away. We just happen to have the tools to be able to watch our Sun in ways we never could before and learn how it — and all stars like it — work, from a very convenient distance of 93 million miles away.

And if that’s not awesome, I don’t know what is.

See more images of our nearest star on the SDO website here, and see images I’ve processed from SDO from the last solar maximum here.

Video credit: NASA/SDO

April 16 2012 CME with Earth
Coronal Mass Ejection on April 16, 2012 imaged by SDO with Earth shown to scale. (NASA/SDO/AIA/ Jason Major)

2 Comments Add yours

  1. Great articles Jason. It’s nice to hear /read , you write well.

    Like

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