A giant wall of heated gas rises from the sun's surface in a false-color photograph taken by solar observer Stephen Ramsden last Friday. Known as prominences, these solar features are anchored to the sun's surface but can extend many tens of thousands of miles into space.
"If you see [videos] of these things, they're constantly in motion," said Joseph Gurman, a solar astronomer at NASA's Goddard Space Flight Center in Maryland.
"The material doesn't actually stay up there for very long. It's constantly being replenished."
While solar prominences are fairly common, the ones captured in recent photos by solar observers around the world are unusually tall and look to be on the verge of being ejected into space, Gurman said.
Gurman estimated that this particular prominence is about 62,000 miles (100,000 kilometers)—or roughly the width of eight Earths—tall.
The dark section at the bottom of the photograph is the surface of the sun, which photographer Ramsden artificially blackened so it wouldn't overwhelm the other solar features.
Image courtesy Stephen Ramsden
Looping the Sun
A bright, sinuous line of superheated gas, or plasma, loops around the rim of the sun on November 12. U.K.-based solar observer Pete Lawrence captured the picture using a filter-equipped telescope.
The solid black squares obscuring parts of the sun may be results of the image having been stitched together from smaller photographs, NASA's Gurman speculated.
"You could make images like this with a four- or five-inch telescope if you have really good optics and a special filter," Gurman said.
These gas loops are called solar prominences when viewed against space and solar filaments when viewed against the sun's surface. A gas loop can also be both a prominence and a filament, like the one captured in this image.
Prominences and filaments differ from solar flares in that prominences are typically less energetic and cooler, Gurman explained.
Also, prominences can linger for weeks or months at a time, while flares are much shorter-lived events.
This composite image, taken by Indiana-based solar observer Mike Borman November 13, shows both the full disk of the sun as well as prominences at its edges.
The circular blemishes on the solar surface are sunspots, regions of intense magnetic activity. Each sunspot in this photograph is about 31,000 miles (50,000 kilometers) across—or the width of four Earths, NASA's Gurman said.
"This massive prominence stands more than 50,000 miles [80,000 kilometers] high and stretches 150,000 miles [241,000 kilometers] across the edge of the solar disk," solar observer Alan Friedman wrote on his blog after taking this picture November 12 during a visit to the Buffalo Museum of Science in Buffalo, New York.
It's the "biggest hurl of hydrogen plasma that I have seen in years," he added.
Said NASA's Gurman, "You can see the fine-scale features here, which gives you a better idea of how filamented the material in a prominence really is."