Coronal Mass Ejection
Written by Fraser Cain
Some of the most dramatic features on the Sun are the gigantic coronal mass ejections. These are huge bubbles of gas formed by the Sun's magnetic field lines. Over the course of several hours, they're ejected from the Sun's corona into space. If the ejection is directed towards Earth, this plasma from the Sun can interact with our magnetic field, producing beautiful auroras.
Coronal mass ejections were unknown until the space age, because the light from the obscured them. In order to see a coronal mass ejection, astronomers use a coronagraph, which allows an instrument to block the light coming directly from the Sun. The fainter atmosphere of the Sun, including the coronal mass ejections are then visible. The first spacecraft to make observations of coronal mass ejections was NASA's Orbiting Solar Observatory, from 1971 to 1973.
A typical coronal mass ejection can release 100 billion kilograms of solar material, and the speed of this material can approach 1000 km/second. In fact, solar flares and coronal mass ejections are the biggest explosions in the Solar System, approaching the power of one billion hydrogen bombs.
Coronal mass ejections are often associated with sunspots and solar prominences, but they can also just happen on their own too.
We have written many articles about coronal mass ejections. Here's an article about viewing a coronal mass ejection in 3D, and here's a video of one.
NASA has several articles about coronal mass ejections. Here's one, and here's another from Windows on the Universe.
We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.
Filed under: Astronomy
