The Universe is 13.75 billion years old.It is easy to say, but what does that mean in Earthly terms?Let’s squeeze the whole history of the Universe into a year! Just to clear, we’re putting things into perspective by compressing the Universe’s whole 13.75 billion years since the Big Bang Read more…
Our galaxy, the Milky Way, is just one of an enormous number of galaxies spread throughout a vast Universe, which is expanding.Everyone knows these facts now, but how do we actually know about our place in the Universe? Light travels through space as a wave, and hence light has Read more…
A long, long time ago when the first stars and galaxies were forming, the Universe was filled with electrically neutral hydrogen. This thin soup of gas absorbed ultraviolet light and all of space would have seemed filled with softly glowing fog. The light of the first generation of stars was Read more…
In more than twenty years of hard work, the Hubble Space Telescope (HST) has made both beautiful images and profound discoveries, sometimes doing both at the same time. What are its greatest contributions to science? Hubble has enabled us to estimate just how big and how old the universe is Read more…
Neutrinos travel faster than light! The science world is agog at this unexpected announcement from CERN in Switzerland. This result has to be verified, for if true it seems that one of science’s central tenets is wrong! It’s all Einstein’s fault of course. Albert Einstein (1879-1955) came up with Read more…
Time is among the most mysterious of fundamental quantities. Time was originally defined and quantified through astronomy, and today astronomers are used to glibly talking of vast stretches of time. But even after Einstein showed time to be an elastic, changing thing we still have to resolve all its mysteries. Read more…
Galaxies, distant from us in space and time, have been in the news recently. Astronomers knew that far away galaxies (and hence ancient galaxies)were smaller than those galaxies closer (in time and space) to us today in the Milky Way. It was believed that the first galaxies appeared less than Read more…
In, say 1975, there was only one kind of ‘stuff’ in the Universe, matter made of protons and neutrons. By 1985 there was a consensus that this was not enough, the gravity of the stars in galaxies was not sufficient to hold them together. Something else was there, vast, mysterious Read more…
We all love bright and showy spiral galaxies! So much so, that we tend to overlook the elliptical galaxies which make up about 30% of the galaxies out there. Smaller than spiral galaxies, elliptical galaxies may be full of stellar living fossils, surviving virtually unchanged from an older cosmic era. Read more…
Here’s how rainbows are made. Some 13.7 billion years ago, a mere millionth of a second after the Big Bang, the first hydrogen and helium nuclei condensed out of a hot, dense soup of quarks and gluons. It took another 380 000 years or so for conditions in the ancient Read more…