"Fair is foul, and foul is fair: Hover through the fog and filthy air."

So goes the chanting of witches in Shakespeare's Macbeth refering to the smog produced from coal burning in 16th century England. The burning of coal continued into the Industrial Revolution but began to be replaced in the early 1900s with oil and natural gas. However, because of the new industrial revolution occuring in developing countries and the high prices of oil in developed ones, coal is making a surprising comeback.

You might have heard the stories: neutron stars are so dense that one teaspoon would weigh about a billion tons on Earth. These stars were once not so different from our Sun, generally about 4 to 8 times more massive. But when these stars run out of fuel to burn, they have a supernova explosion, and eject their outer layers – and in this particular case, the ejected outer layers formed what we now call our beautiful Crab Nebula (see photo). The inner part of the star, with no more fuel, collapses under its own weight to a sphere about 20 kilometers in diameter. The pressure is so great that protons and electrons come together to become neutrons, and a neutron star' is born. And now, for the first time, an international team of scientists has found a way to look inside these mysterious objects, using an instrument intended to pick up gravitational waves.