We're surrounded by other ‘Earths’: Infographic reveals that more than 2,000 planets could be habitable within just 60 light years of us
- Planets are all in the habitable zone and shown by relative size to Earth
- The habitable zone is area where conditions are ideal for life to evolve
- Scientists claim there 40 billion planets in our galaxy with potential for life
- The infographic shows just over 2,000 potentially habitable planets
Our galaxy - which is around 100,000 light years wide, is thought to have 40 billion planets with potential for life.
The figure is an estimate drawn up from our current knowledge 1049 planets orbiting around other stars, with over 2000 more candidates currently awaiting follow-up observations.
Of those 1049, we know of a dozen planets around other stars with any possibility to support life as we know it.
This infographic by U.S. web comic Randall Munroe shows just over 2,000 potentially habitable planets that scientists estimate could be within 60 light years from Earth.
This infographic by U.S. web comic Randall Munroe attempts to represent habitable planets that could be within 60 light years from Earth
The planets in the image are in the 'habitable' or 'Goldilocks' zone, which is a belt around a star where temperatures are ideal for liquid water to pool on a planet's surface - and support life.
Mr Munroe used existing data to make a visual representation if the size and amount of potentially habitable planets.
Earth is placed in the centre of the infographic to provide a sense of scale, and all the planets are organised by approximate size.
While it doesn’t provide a sense of distance or position, the xkcd image shows that alien life may not be as far as we might think.
Mr Munroe, who is a former Nasa robotocist, created the infographic after news in November that the nearest habitable world is near enough to see with the naked eye.
Goldilocks zone is a belt around a star where temperatures are ideal for water to pool on a planet's surface
WHAT IS THE 'GOLDILOCKS ZONE'?
The hunt is on for planets about the size of Earth that orbit at just the right distance from their star - in a region termed the habitable zone.
The habitable zone is the belt around a star where temperatures are ideal for liquid water -- an essential ingredient for life as we know it -- to pool on a planet's surface.
To determine the location of a star's habitable zone, scientists have to first learn how much total radiation it emits.
Knowing precisely how far away a habitable zone needs to be from a star also depends on chemistry.
For example, molecules in a planet's atmosphere will absorb a certain amount of energy from starlight and radiate the rest back out.
How much of this energy is trapped can mean the difference between a turquoise sea and erupting volcanoes.
Researcher Andrew Howard said: ‘Potential sites for life to get started are abundant in the galaxy
‘We still don’t know how easily life can spring forth on a potentially habitable planet but with 40 billion chances, I’m optimistic that we’re not alone.’
The findings, detailed in the Proceedings of the National Academy of Sciences, were based on a statistical analysis of observations made by Nasa's now-crippled Kepler space telescope.
Scientists used data collected by Nasa’s Kepler telescope, which took photographs of 150,000 stars every 30 minutes for four years.
These images were then analysed for small but regular dips in the star’s light – a telltale sign that a planet is passing in front of it.
Some 42,000 of the stars monitored were like the sun or slightly cooler and these had 603 planets orbiting them.
Ten of these were Earth-like, that is, roughly the size of our planet and just the right distance from their star for it to be neither too hot or too cold for life to survive.
After accounting for holes in the data, they estimated that 22 per cent of all sun-like stars are circled by a planet that could be suitable for life.
‘Our galaxy has 40 billion chances for life to get started and evolve,’ said Dr Howard, of the University of Hawaii.
‘Today, more than ever we need to focus on searching for intelligent life.’
The relative sizes of Kepler habitable zone planets discovered in April are shown (from left to right) Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth
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