A recent spate of Sun spots and solar flares have solar physicists wondering whether a total eclipse that will glide across Africa on Thursday might be more fantastic than usual.
As with all total solar eclipses, this one will afford a rare opportunity to view the Sun's usually inscrutable corona as a shiny, spiky silver crown around the Moon as it slips exactly between the Earth and Sun.
A peak in the Sun's 11-year solar activity cycle is thought to have passed earlier this spring, but the Sun continues to churn out more gas and charged particles than usual -- a phenomenon that could make views of the Sun's corona during the eclipse more dramatic and scientifically revealing.
"Seeing a coronal mass ejection billow across the sky a couple of degrees would be pretty cool," said Tony Phillips, a solar weather forecaster at NASA's Marshall Space Flight Center (MSFC).
Sunspots are extremely large magnetic fields that appear as dark circles on the surface of the Sun. Solar flares and coronal mass ejections are associated with these spots when the roiling activity of the Sun's surface makes the concentrated magnetic fields unstable. When this happens, large arcs of heat and sub-atomic matter plume from the surface of the Sun out into the corona. With the Moon acting as a shield, these activities could be visible to the naked eye during the solar eclipse.
Brief window
Phillips, though, is doubtful that the Sun will put on more of a show than usual during the eclipse. There are three sunspots sitting in the middle of the disc today, but the odds are against them for producing visible flares. First of all, says Phillips, the timing of the phenomenon would have to be impeccable.
David Hathaway, head of NASA MSFC's solar physics group, explained, "The one problem is that you only have a brief look. It's only five minutes, so it'd be hard to see changes due to an eruption. Even from the beginning to end, the corona can often be hard to see."
Secondly, coronal mass ejections stick close to the surface of the Sun, meaning the Sun spots would need to be closer to the sides, or limb, of the disc for ejections to be visible. The Sun takes 27 days to make a full rotation, so today's spots will be closer to the western side not the edge, says Phillips.
Nonetheless, the "behavior of a Sun spot is just as predictable as a tornado," Hathaway said. The Sun still could surprise us.
Whatever the case, the eclipse will most likely be very beautiful. "Any Sun spots cause a lot of pointed streamers in the corona, unfurled in all directions," Hathaway said.
Sunspots also give the corona a more rounded shape, rather than just the normal prominence in the eastern and western limbs.
The eclipse is not viewable in the United States. The path of totality streaks through Mozambique, Namibia, Angola, Madagascar, Zambia and Zimbabwe on Thursday, with totality coming at 9:12 a.m. EDT. Check SPACE.com for
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