The Earth is the jewel of the Solar System, the only world orbiting the sun that is teeming with life. This comes as no surprise when you examine the nature of life. All life on Earth, from microbes to human beings, is based on the carbon atom. It is difficult to conceive of a different form of life, because carbon is the only element that can join with itself and other elements to create large and complex molecules. Within the Solar System, only the Earth has a mass and surface temperature that allows these complex molecules to exist in abundance. If we are to find other worlds with complex living organisms we have to look beyond the Solar System to other stars
Stars vary enormously in their physical properties, and only 5% could host a world similar to the Earth. It just so happens that not one but two of these stars are to be found on our cosmic doorstep – at Alpha Centauri.
On an autumn evening the Southern Cross comes almost overhead. Following the Cross is the two ‘Pointer Stars’. The brighter of the two Pointers is Alpha Centauri, the nearest star beyond the Solar System. Its distance is 4.35 light-years.
Seen in a telescope, Alpha Centauri is, in fact, a glorious double star. The two stars, both of which are similar to our sun, orbit their common centre of gravity every 80 years. Until recently the concept of worlds orbiting around other stars was just a theory. We didn’t have the technology capable of detecting them. That has all changed and we have now identified thousands of planets around other stars. This includes the stars of Alpha Centauri.
Research continues to identify the properties of the Alpha Centauri planets. Think about it. What would it be like to live on a world with two suns? Has advanced life developed on one of these worlds? This could be a concern because the Alpha Centauri system is more than a billion years older than our Solar System.
Richard Hall
Stonehenge Aotearoa
Photo credit – Davide De Martin/Mahdi Zamani – produced by the European Southern Observatory (ESO)