Death and Rebirth
On July 4, 1054 A.D, a bright new star appeared in the sky. Although it was 6,500 light-years away from Earth, it shone brighter than whole galaxies and was visible in daylight for 23 days. Little did the astronomers of the day know, the “new” star was actually the violent death of an old star: a supernova explosion. Stars more than ten times the mass of our sun will eventually become supernovas when they die. For their whole lives, they battle to balance energy trying to get out and gravity trying to crush them in under their own weight—but when they run out of fuel to burn, gravity wins. The star’s core collapses and its very atoms are crushed, emitting an enormous shockwave that flings heavy elements out into space. The remnants of this particular supernova formed the enigmatic Crab Nebula, an energetic cloud spanning five light-years, with each different colour representing different chemicals: orange is hydrogen, red is nitrogen, green is oxygen… And at the centre of the nebula lies the remnant of the exploded star. Gravity has squashed all the empty space out of it, leaving an incredibly dense object called a neutron star—just 20 km across, but with the mass of our sun, so on Earth, one teaspoonful would weigh one billion tons. Rotating neutron stars are known as pulsars, and this one spins at a rate of 30 times per second, sending out violent jets of particles at nearly the speed of light.
(Image Credit: 1, 2)