A Hole on the Sun

coronalholeThe Solar Dynamics Observatory took these images of a large coronal hole on the Sun last week. Coronal holes are the source of a high-speed wind of solar particles that streams off the Sun some three times faster than the normal solar wind. It’s not clear what causes coronal holes, but they correlate to areas on the Sun where magnetic fields flow away from the surface without looping back as they do elsewhere.

Image Credit: NASA

Happy New Year, Sun

20150101_001043_coronal_holeWhile people on Earth celebrated the New Year with fireworks, the Sun was quite with very few small flares. Indeed, this image from the Solar Dynamics Observatory shows a huge coronal hole present just after midnight on 1 January UTC.

Coronal holes are regions of the Sun’s corona where the magnetic field reaches out into space rather than looping back down onto the surface. Particles moving along those magnetic fields can leave the sun rather than being trapped near the surface. Those trapped particles can heat up and glow, giving us the lovely AIA images. In the parts of the corona where the particles leave the sun, the glow is much dimmer and the coronal hole looks dark.

Image Credit: NASA

Coronal Hole Squared

A nearly square coronal hole was one of the noticeable features on the Sun this past week. A coronal hole is an area from which high-speed solar wind streams into space. It appears dark in extreme ultraviolet light because there is less material in that region emitting those wavelengths. Inside the coronal hole you can see bright loops where the hot plasma outlines small bits of the solar magnetic field sticking above the surface. Since this hole is so far south on the Sun, there is less chance that its solar wind stream will strike the Earth.

[youtube http://www.youtube.com/watch?v=pxUBhrd3_C0]

Video Credit: NASA

A Coronal Hole

A very large coronal hole rotated across the middle of the Sun to be in a position to affect Earth last week. In this animation of views by the Solar Dynamics Observatory in extreme ultraviolet light, the dark region shows where the magnetic field of the Sun was more open, emitting streams of high-speed solar wind. Over the next few days, this solar wind is likely to impact Earth’s magnetosphere and possibly cause displays of aurora.

[youtube http://www.youtube.com/watch?v=xNISXItrPLg]

Video Credit: NASA