But when we see a filament in profile against the dark sky it looks like a giant glowing loop - these are called prominences and they can be spectacular.' 'When you look down on top of them they appear dark because the gas inside is cool compared to the hot photosphere below. 'Filaments are formed in magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun,' explains Hathaway. 'Still, it's worth looking just in case.' 'Another problem is that bright moonlight will render faint aurora practically invisible,' added Heckman. It's hard to make a definitive forecast because this type of eruption is so rare.' It was a very large flare, but it produced only a minor geomagnetic disturbance. 'There was an event very similar to this one on July 29, 1973, during Skylab.

'The incoming CME might produce an auroral display, but there's no guarantee,' cautioned Gary Heckman of the NOAA Space Environment Center. Many stargazers will be out to see the late-summer Harvest Moon, so the CME could arrive on a moonlit night while many people are looking at the sky. The situation this week could be much the same. Left: Wade Clark captured this image of the Big Dipper shining through green-colored auroral sheets in the skies above Skagit County, Washington State on August 12, 200. Legions of meteor-watchers saw a brilliant auroral display in spite of glaring light from that night's nearly-full Moon. The last time this happened was August 12, 2000, when the shock wave from a CME arrived at Earth just hours before the peak of the annual Perseid meteor shower. Indeed, many skywatchers greet news of a full-halo event with enthusiasm because CMEs can trigger memorable displays of aurora when they strike Earth's magnetosphere (a region of space around Earth protected by our planet's magnetic field). There is no upper limit to the Corona.Although CMEs may sound menacing, they pose little danger to Earthlings. We are able to see it during a solar eclipse, or by using a special device called the coronagraph. It is impossible to see the Corona with the naked eye, but there is an exception. It starts at about 1300 miles above the photosphere, and its temperature is measured to be around 900,000 degrees Fahrenheit. There are four outer layers of the Sun, and the Corona is the outermost one. The outer layers are the Corona, the Transition Region, the Chromosphere, and the Photosphere, while the inner layers are the Core, the Radiative Zone, and the Convection Zone. The layers of the Sun are divided into two larger groups, the outer and the inner layers. However, we can determine the internal structure of the Sun, and it is made up of seven different layers. Because the Sun is mostly composed of helium and hydrogen and is not solid, it does not have an outer boundary that is clearly defined. The critical difference is that the Sun is not solid, unlike Earth, so the layers are a bit harder to determine. Just like our planet, and most other celestial bodies, the Sun is divided into distinct layers.

Sun corona facts