Explanation:
Swinging inside the orbit of Mercury, on April 20th periodic
comet Encke
encountered a blast from the Sun in the form of a
Coronal
Mass Ejection (CME).
When CMEs, enormous clouds of energetic particles ejected from
the Sun, slam into
Earth's magnetosphere, they often trigger
auroral displays.
But in this case, the collison carried the tail of the comet away.
The tail was likely ripped off by interacting
magnetic fields rather than the mechanical pressure of the
collision.
Clicking on the two panel image will play a movie gif of the
remarkable event as recorded by the
Heliospheric Imager onboard the
STEREO A spacecraft.
In the movie, the time between frames is about 45 minutes,
while the frames span about 14x20 million kilometers at the
distance of the comet.
Of course, similar collisions have happened
before as the ancient comet loops through
its 3.3 year solar orbit.
So don't worry, Encke's
tail grows back!
