The Origin of Stars, Planets and Us

UK science teams are working on several missions that search for evidence of our origins in the depths of space.

Space telescopes like Hubble and XMM-Newton look out at the furthest reaches of space, collecting light from the youngest galaxies. They will be joined in the future by the Herschel Space Observatory, the James Webb Space Telescope and the Planck mission, all gathering evidence on the origin of the Universe, stars and planets.

Spacecraft also look for clues about the origin of life. Hubble can detect molecules of life on planets outside our Solar System, while Cassini Huygens and Rosetta seek answers by visiting our neighbours in space.

The ExoMars mission will visit Mars with the UK-devised Life Marker Chip (LMC), built to detect evidence of life under the surface of our nearest planet. Each new mission and every fresh discovery brings us closer to a better understanding of who we are, where we come from, and — ultimately — what the future might hold.

The Big Bang

The Big Bang is the only widely accepted model of how the Universe has developed over time. Astronomers have observed that the Universe is expanding and cooling. The crux of the Big Bang theory is, if you could turn the clock back, then earlier in time everything would have been denser and hotter. And the further back you go, the denser and hotter things get.

The theory’s name seems to suggest that the Universe started with a huge explosion. This is a misconception. According to the Big Bang model, the origin of the Universe was not an explosion of matter into already existing space - but the very beginning of space and time.

So why the name Big Bang? It was originally given by detractors to mock the theory and is a bit of name-calling that stuck!

Stars, planets and us

Observations and simulations have helped astronomers understand how star formation led to the formation of planets and even life itself.

The origin of stars

As the early Universe expanded, raw energy condensed into matter. Gas particles were pulled together under gravity to form clouds, called nebulae. Within these nebulae, the dense areas continued to grow ever denser under gravity, spin and heat. Eventually, the enormous pressure caused nuclear fusion to begin and stars were formed. This is how our own Sun began.

The origin of planets

The Hubble Space Telescope has captured images of planet-like disks around young stars. This leads us to believe that planets are formed from the debris of star formation. Left-over particles of gas and dust are bound together under gravity to form rocky and gaseous bodies around the star.

The origin of life

In the very act of living — and dying — stars fuse hydrogen to create all other elements in the Universe before returning them to space. This includes carbon, oxygen, calcium and all the elements that make up the molecules in our bodies. In the words of the late astronomer and former science fiction writer Carl Sagan: "We are all made of stardust".

Theories about the origin of life on earth are being tested and explored through a number of BNSC-backed missions:

Rosetta is on its way to study a comet up close. It is believed that much of the water on Earth was brought here by comets, so it is possible that the complex organic molecules that formed the basis for life also came from cometary debris.

Cassini Huygens visited Saturn’s largest moon, Titan. This moon has an atmosphere similar to Earth's when it was a young planet. By studying Titan, scientists hope to gain an insight into how life might have first become established on Earth.

The Aurora programme will help establish if life originated on other planets. UK scientists are developing the Life Marker Chip (LMC) instrument for ExoMars. This will look for signs of life below the surface of Mars.