They are named after NASA's ‘space observatory’ Kepler – the spacecraft that ‘spotted’ the planets in the Kepler-62 system. Scientists announced their discovery last week, and have attracted much media and expert interest due to their unique conditions.
The two new planets are located in their star system’s ‘Goldilocks Zone’ – the region around a star that is considered habitable. They are also the right size to potentially allow the development of liquid water and a life-friendly atmosphere. However, it is likely to prove a long time before we’re able to confirm their habitable status, let alone whether they have their own life-forms.
Kepler mission
The Kepler spacecraft is named after 17th-century astronomer Johannes Kepler who theorised laws of planetary motion. Launched in 2009, the unmanned craft is a sort of space telescope. It uses a photometer to monitor the light given off by stars in distant areas of the Milky Way. Transmitted to Earth, this data is then analysed to try and recognise any potential ‘dimmings’ in the levels of starlight – the light changes potentially caused by planetary bodies passing in front of their respective stars.
As of January, over 2,700 ‘planetary candidates’ had been discovered by Kepler, with 122 of those having been confirmed as exoplanets by other forms of observation. However, only a small amount of these are likely to prove potentially habitable. Kepler-22b was the first planet to be located in a system's habitable zone.
The Kepler mission has been extended to 2016, with a follow-up mission called the Transiting Exoplanet Survey Satellite (TESS) set to launch the following year. TESS will examine a much wider area of the sky than Kepler currently does.
Conditions for life
As well as existing within the limits of the Goldilocks Zone, a planet needs to fulfil a range of criteria to prove a potential candidate for life. Planets too close or too far from a star will be too hot or cold to support life.
Planets further need to have a solid surface and be able to support liquid water. Those that are too small are unable to support a habitable atmosphere, ending up more like our moon. Planets that are too large are likely to be gas giants similar to our own Jupiter and Saturn.
Kepler 62
The two recently discovered planets are reported to be ‘Super-Earths’, with Kepler-62e 60% larger than the Earth and Kepler-62f about 40% larger. These are theoretically life-supporting sizes, with scientists predicting the planets are probably entirely covered by water. Given these conditions, and the fact that Kepler 62 is 2.5 billion years older than our own solar system, life would likely be extremely different to our own planet.
Scientists’ excitement over their discovery stems from the fact that there are two candidates for life in a single system – a rarity in current space investigation.
At well over 1,000 light years away from us, however, Kepler 62 is out of our reach, with current telescope and monitoring technology unable to examine the system in any depth. Kepler satellite data, however, allows scientists on Earth to direct attention towards it and other potential host systems, in the hope that we might perhaps pick up some transmission from a distant intelligent life (and vice versa). Given the incomprehensible scale of even our own galaxy, the existence of life somewhere out there is extremely likely - finding it is the ongoing challenge.
