It’s definitely a great time to be alive, at least from my perspective as an evolutionary biologist interested in all facets of science. I remember only a decade or so ago searching for other planets, let along Earth-like planets, was a mere speck on the horizon of the science of astronomy. However, the past few years have seen interstellar leaps and bounds in our hunt for Earth 2.0.
In the past it was thought that planets would be incredibly hard to find, if not impossible. But today it’s widely accepted by astronomers that almost every star will have a number of Earth-sized planets in orbit around it. If that’s the case, and there are 200 billion stars in our galaxy, that may mean there are 400 billion Earths here too… 400 BILLION!? Without even considering the number of galaxies that exist in our universe, it becomes obvious that extraterrestrial life almost certainly exists, and exists in our galaxy, and most probably in relative proximity to our Earth.
One of our most advanced weapons currently at our disposal in this battle to find signs of galactic siblings is the Kepler Space Observatory. This extremely power telescope is the first instrument created that is capable of detecting alien planets. It is trailing behind the Earth, following its orbit of the sun, while focused on the constellation Cygnus, gazing at an estimated 150 000 stars. Taking picture after picture, minute after minute, with the simple objective of looking any stars among the 150 000 that dim. When a star dims it is evidence of a planet rotating around it. As a planet passes in front of its star light a minute amount of the star’s light is blocked causing it to faintly dim.
How long the star dims and how much light is blocked reveal the size of the planet and the distance from its sun. A good analogy for this process is looking for the dip in the light that you would see in a searchlight if a moth passed in front of it. It is only minute but it is measurable.
Initially scientists estimated that the Kepler telescope would find a minimum of 50 Earth-like planets. As of December 2011 2 326 candidate planets had been discovered, 207 of which were Earth-sized, and 48 of these planets are located in the habitable zone with the potential to be home to alien life forms.
Before any of these candidate planets could be confirmed as being an Earth 2.0 it was required that they had to be viewed to transit their star 3 times. The first Earth 2.0 was confirmed within the last month and has been given the name Kepler 22-b by its discovering scientists. It has a year of 290 days long, and is a super-Earth at 2.4 times the size of our Earth. That said, it is so far the smallest planet to be found within the habitable zone of star similar to our sun. Although the planet is approximately 15% closer to its sun than our Earth, its sun only puts out 75% of the energy of our sun. Models suggest it has an average temperature of a cosy 22C, perfect for sustaining life (and almost warm enough for a nice day at the beach). However, scientists are still unsure as to whether or not it has a composition predominantly of liquid, gas or rock.
Scientists state that one of their biggest concerns when looking for extraterrestrial life on these sorts of planets is the possibility that they will be unable to discern its presence despite the discovery of the planet on which it resides. This may happen if the alien life forms are drastically different from our own here on Earth, so much so that it is unrecognisable.
Whether or not that remains a difficulty, it’s still clearly a wonderful time to be alive and right on the edge of such discoveries. Hopefully it is only a matter of time before science discovers alien life forms, whether basic or complex, allowing us to finally say we are not alone!
Below is a wonderful documentary called Weirdest Planets that describes a few of Kepler’s early findings.