The birth of a sunspot cluster

Bad Astronomy
The entire universe in blog form
April 19 2011 7:00 AM

The birth of a sunspot cluster

Ever wanted to see how sunspots form and change as they grow? The folks working with NASA's SDO satellite just released this amazing video of the adorable younglings.

Not much happens until about 18 seconds in, and then a lot happens.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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That is so freaking cool. Taken over the course of two weeks (half a rotation of the Sun), you can see them pop up, darken, and grow, and even rotate a bit as the Sun's complex magnetic fields change... and the neatest part to me is the foreshortening they undergo as they approach the east side of the Sun's disk. Amazing!

Sunspots are actually regions of slightly cooler material at the Sun's surface. Hot plasma (ionized gas, stripped of one electron or more) rises from the solar interior, reaches the surface, cools off, and sinks back down. This is called convection, and is the same process you see in a pot of boiling water. But at the surface, the tortured and twisted magnetic field of the Sun can suppress convection, preventing the cooler material from sinking. Since the brightness of the plasma depends on the temperature, this cooler stuff is darker. Boom! Sunspot.

Or, in this case, sunspots. You can see five of the suckers here, changing and mutating as the plasma interacts with the magnetic field. I recognize these spots, too: they were responsible for the first X-class flare of the season on March 15th. There's dramatic footage of that as well which I posted on my blog at the time. They're busy spots; they blew out a lower energy flare a few days earlier, too.

And here I am calling them cute and little when they're actually comfortably bigger than the Earth and exploded with the energy equivalent of millions -- millions! -- of nuclear bombs.

Good thing they're 150 million kilometers away. That lessens the impact, but doesn't negate it. The more we learn about the way sunspots behave, the better. SDO, STEREO, and the rest of our sunward-looking fleet are teaching us a lot about our nearest star. And we'll need that information as we enter the beginning of yet another solar cycle.

Video credit: NASA/SDO



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