Why do asteroids break up when no where near the Suns heat?
The current thinking is that asteroids are dirty snowballs - composed mainly of ice and rock fragments - mainly due to the millions of miles long glowing tails and the theory of planet building. But as scientists admit, it is a real puzzle why an asteroid would break up when so far from the Sun that there is no heating effect on its surface, to melt it.
"Seeing this rock fall apart before our eyes is pretty amazing,"
They said that the break up is also unlikely to have been caused by interior ices warming and vapourising because it is too cold – being nearly 300 million miles from the sun.
Asteroid break-up captured on film for the first time | The Guardian
A rock asteroid having come from deep space would be electrically charged due to space plasma (gas plasma makes up over 99% of the visible mass of the universe and is what the 'vacuum' of space is made up of - slightly electrically charged gas). As it gets closer to the Sun the solar winds (charged plasma being accelerated away from the Sun - like the CERN project? - with 2 different speeds of solar wind!) there could be an electrical difference - causing discharges and electrical stress.
comet Hartley 2 ... shows jets and where they originate from the surface. There are jets outgassing from the sunward side, the night side, and along the terminator -- the line between the two sides.
Jets Galore | NASA
There would be more electrical difference at line where you have the dark side - not being hit directly by the plasma wind - compared to the more energised area being charged by the plasma wind?
Electrical discharges or electrical machining - the numerous extra 'tails' that appear, disappear and move around the asteroid - could cause the asteroids surface to be removed - the immensely long comet tail.
If the tail particles/gases are electrically charged or part of the electrical discharge of the asteroid then perhaps this explains why the tails appear to glow - an effect like the northern lights or neon lighting?
If an asteroid is made up of rock and not a dirty snowball then this would also help to explain the recent puzzle and struggle of what is the difference between a comet and an asteroid? They are perhaps the same thing, just with different orbits. You can read this article Comet, Asteroid, or what? (especially at the bottom) that shows the real puzzle of is it a comet or an asteroid or even an active asteroid!
NASA's Deep Impact mission
NASA's Deep Impact mission had a very surprising effect for astronomers. NASA sent the Deep Impact probe to crash into comet Tempel 1. They were basically expecting a large puff of dust, as the metal object slammed into the dirty snowball.
It seems that even a fraction before the Deep Impact probe hit the surface of comet Tempel 1 there was a massive explosion that blinded the watching cameras. A logical explanation could be that there was an electrical discharge between the 2 objects, especially as one of them was metal. Similar to when we get a shock of a metal cabinet, car or another person. The blinding light continued after the initial moment of collision.
This spectacular image of comet Tempel 1 was taken 67 seconds after it obliterated Deep Impact's impactor spacecraft. The image was taken by the high-resolution camera on the mission's flyby craft. Scattered light from the collision saturated the camera's detector, creating the bright splash seen here. Linear spokes of light radiate away from the impact site, while reflected sunlight illuminates most of the comet surface.
Tempel Alive with Light | NASA
For those who follow the Electric Universe Theory the explosion was not a shock, it was predicted. This long article The Deep Impact of Comet Theory posted before the collision predicts what would and would not happen, basing it on it being an Electric Universe. Read the section ELECTRIC MODEL PREDICTIONS FOR DEEP IMPACT to perhaps explain some of the mysteries of the Deep Impact results.