If you look up into the sky on a clear night, you would see thousands of stars. There are surely many more that you would need a telescope to see. But there are not stars everywhere. You can zoom in further and further with bigger and bigger telescopes, until eventually you find gaps where you simply don’t see stars. For a long time it was thought that the gaps were empty, until the Hubble telescope peered through the darkness by taking a 200 hour exposure of a supposedly empty patch of sky. What it revealed was a universe full of...
Time is a very slow thing when we talk about the universe. Stars can live for many Billions of years, and over human timescales they seem stagnant and unchanging. So it’s no surprise that when we look at distant galaxies, they don’t appear to change at all over the course of centuries. But appearances can be deceiving. Galaxies do change, more quickly than you would imagine. M87, pictured above, is a monstrous Galaxy of nearly 1 Trillion stars, more than twice as populous as the Milky Way. It looks like a big fuzzy star, and it quite regular in appearance...
If you could see through the lens of a very powerful telescope, to an area of sky the size of a grain of sand held at arm’s length, a new universe would be revealed to you. For in that tiny patch of seemingly empty sky, there are thousands of galaxies visible, albeit with many hours of light collection. Observing the most distant of these galaxies, at the edge of the universe, allows us to estimate the number of Galaxies present in the distant past, when the universe was very young. As our observations improve, and our ability to simulate the conditions of the...
When the first stars and galaxies started to form, it was like a spark of a massive chain reaction where the vast amounts of gas and dust that had clumped together were quickly converted into dense, luminous star clusters. This was the beginning of the formation of the heavier elements that would eventually make up all that we see on the planet Earth. But when did this massive tirade of star formation end? When we look at galaxies in the present epoch, most don’t form stars very rapidly at all, and giant elliptical galaxies are all but devoid of gas,...
