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 into the 365 days of a year. Note that intelligent life doesn’t show up until nearly the end (SETI fans take note!)
Midnight 1 January:The Big Bang occurs, almost certainly marking the creation of the Universe.The new-born cosmos undergoes a short period of extremely rapid growth called Inflation, accompanied by cooling.The first elements – only hydrogen and helium – appear, existing in a very hot ionised state.
2.30 am 1 January:Radiation from the Big Bang permeates space, today we see this as the Cosmic Microwave Background.The Universe is still veiled with a murk of neutral hydrogen and helium atoms.Even the brilliant ultraviolet radiation of the first stars cannot escape these curtains of gas, astronomers call this era the cosmic Dark Ages as we cannot see look back and see what was happening.
4-26 January:The Age of Reionisation, as the first galaxies form.The intense radiation they emit reionizes the gases spread through the surrounding Universe, ending the Dark Ages.From this point on, space becomes transparent and starlight can travel freely through space.The most distant galaxies in the celebrated Hubble Ultra Deep Field existed at the end of this era.
22 February:The Milky Way forms from many smaller galaxies gravitationally attracted together.The cores of of some of these embryonic galaxies can still be seen today as the globular clusters orbiting the Milky Way.
31 July:The Solar System, planets and the Sun, forms in a vast stellar nursery, probably the consequence of the shockwave from an exploding star slamming into an ancient giant molecular cloud.
21 September:The Late Heavy Bombardment, an era of violent asteroid impacts throughout the Solar System, finally ends. If you want to know how bad this was, look up at the Moon. The dark bits, the maria, are the scars of gigantic asteroids strikes during this period.It surely is no coincidence that life arose on Earth (perhaps not for the first time) in this calm after the storm.
4 December:Fossil evidence suggests that the first multicellular life appeared about now.Building larger and more complex organisms out of lots of cells was the next tiny step towards Earth life one day building spaceships.
17 December:Conscious of how time is moving on, and how far advanced the Sun is getting in the Main Sequence, the first vertebrates arise about now in the shape of some dodgy fish wannabes. Vertebrates are the back-boned group of creatures including fish, amphibians, reptiles, birds and you and me.
29 December:A 10 km diameter asteroid in the Gulf of Mexico causes a dramatic mass extinction which proves too much even for the proper dinosaurs (by which I mean T-Rex and Triceratops, rather the feeble feathered ones we have today).
11.47pm 31 December :First modern humans were to be found in Africa about now.
Midnight 31 December NOW!
I wonder what will happen next year?