coronal holes are the darker areas in this X-ray image — one at the top center and another capping the solar south pole, about where Antarctica is on Earth.A Japanese-led satellite mission that's studying the sun in extreme ultraviolet and X-ray wavelengths has revealed gaping holes in the solar corona through which plasma can easily escape into space. The so-called
Scientists believe the sun's magnetic field traps jets of plasma from the sun's surface, heating up the solar atmosphere, or corona, to millions of degrees. Coronal holes represent gaps in the magnetic field, allowing the plasma to stream straight out into space. The lack of trapped plasma also means the holes are relatively cool in temperature, compared to the active regions nearby.
The Hinode satellite, which made this image, is part of a swarm of scientific instruments dedicated to monitoring the sun to help scientists improve forecasts of space weather. Coronal holes are thought to be the start of the space weather chain that can wreak havoc on Earth by knocking out communications satellites and power grids.
SpaceWeather.com is one of the best places on the Web to keep yourself up to date on the solar outlook. Today's highlights include the passage of an active sunspot around the sun's far side, plus an amazing Hubble flare and a beautiful recap of last week's northern lights.
More stories on sun and space weather:
- Astronomers discover source of solar wind
- Sun's magnetic secret revealed
- Hot news: See the sun's corona in full
- Sun's super-hot shell cooked by plasma jets
Tip o' the Log to Ian O'Neill at Discovery News.
John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).