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Coronal Mass Ejection
A few times every day during solar maximum conditions, the Sun can let loose a titanic
blast of material. For days, a heated cloud of plasma can be suspended by magnetic
pressures just above the photosphere in a region called the chromosphere. Then, for
reasons not fully understood, this billion-
As it enters the lower reaches of the solar corona, the Sun's outer atmosphere, the cloud expands and accelerates enormously to speeds of millions of kilometers per hour. Within a few days, the cloud has reached the orbit of the Earth, while parts of the cloud itself still envelope the orbits of Venus and Mercury. In time, these coronal mass ejections, or CMEs as they are called, cause interplanetary space to be filled with a changing patina of cloud fragments and magnetic field blobs, millions of kilometers across, and flowing outward in a great pinwheeling pattern, out beyond the orbit of Pluto.
No two CMEs are exactly the same, so astronomers describe these explosions by average properties, just as we often say that the average human being is about 6 feet tall. CMEs are actually not very dense by the time they reach the Earth's orbit. As they expand through space, their density falls from millions of particles per cubic centimeter near the Sun, to barely a dozen particles per cubic centimeter near Earth.
Most of them travel at nearly one million kilometers per hour and take 2-
Source:NASA
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