Universe Today

An eruption on the Sun. Credit: NASA

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Sun sunspots show up during the recent annular eclipse. Credit: Shehal Joseph and Romayne Anthony

Astrophotographers capturing the recent annular solar eclipse on January 15, 2010 got an added bonus: upon closer inspection, they found sunspot 1040 also showed up on their images, too. "We didn't mean to catch sunspots in our Jaffna Eclipse expedition, nor did we plan to," said Prasanna Deshapriya, one of the members of the Eclipse Hunt 2010 crew, featured in our eclipse photo and video collection. "But surprisingly this is what really happened."
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Solar flares on the Sun

The Sun is a ball of hot plasma, constantly in motion through the convection of material rising and falling in its upper layers. The movement of plasma creates magnetic field lines which shift and move. These field lines can twist up and poke out of the surface of the Sun like twisted rubber bands. When the field lines pierce the surface of the Sun, they create darkened areas called sunspots, which can last for days and even weeks. When the field lines reconfigure, they snap into a new position and release a tremendous amount of energy.

It's this release of energy that we see here on Earth as a flare. A single solar flare can release 6 x 10²⁵ joules of energy. Just for comparison, that's about 100 times more than the World's entire amount of energy contained in fossil fuels. Depending on the amount of energy in the flare, it can be released in the ultraviolet spectrum and even as X-ray flares. If a flare is powerful enough, it will generate a coronal mass ejection, blasting out hundreds of billions of tonnes of solar material into the Solar System.

Solar flares effect the space weather around the Earth. The storm of protons and electrons crash into the magnetosphere, changing its shape. This is when we see the most spectacular Northern Lights. Satellites in orbit around the Earth can be damaged during the most powerful solar storms, and astronauts traveling outside of the Earth's magnetosphere (for example, on the Moon) can receive a lethal dose of radiation if they don't have a shielded place to wait out a solar storm.

We've written several stories about solar flares for Universe Today. Here's an article about how there won't be a killer solar flare in 2012, and a killer solar flare seen on another star.

If you'd like more info on the Sun, check out NASA's World Book on the Sun. And here's a link to NASA's SOHO mission homepage.

We've also recorded several episodes of Astronomy Cast about the Sun. Listen here, Episode 30: The Sun, Spots and All.

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MESSENGER on the sunside of Mercury. Credit: NASA

Filed under: Missions, Solar Astronomy | 15 Comments »