The euphoria with which the declaration that an earth-like planet has been found in the universe has been received and flashed in the media just goes to show man’s deep desire to find extra-terrestrial life.
Interestingly, even though the discoverers, Dr. Rene Heller of Max Planck Institute for Solar System Research, Göttingen, Germany, and his team, have cautiously declared the find as a ‘planet candidate’ with 85 per cent confirmation that this signal is genuinely caused by a planet and not by a random statistical variation of the data or by an instrumental effect, media has just glossed over the fact, believing that confirmation will come in due course. Ninety-nine percent accuracy is required to declare a statistical finding as a confirmed planet.
The discovery of a planet like Earth with an orbital period of 378 (Earth is 365 days) days, rotating around a star-like sun around 3,000 light-years away (1 light year = 9.7 trillion kilometers) is an extremely rare event.
Is there life outside the Earth? Is there intelligent life in the universe other than our planet? Answers to these fundamental questions underlie all our endeavours in the field of space, astronomy, astrophysics, and astrobiology.
The punch of the story lies in the tantalising possibilities thrown up by the fact that there is another planet almost like the earth. Even though we do not have the technology to travel the distance of 3,000 light-years today, no one can stop us from imagining a full alien civilization waiting to meet humans there.
The most relevant and crucial aspect of the newly discovered pair planet candidate KOI-456.04 and its star Kepler-160 is that they have a relationship with each other, which is comparable to Earth and Sun system, which makes KOI-456.04 a strong candidate for being an Earth-like planet.
Dr. Sujan Sengupta, professor at the Indian Institute of Astrophysics, Bangalore, an expert in the field of exo-planets said that it was an “important” find because if confirmed it may be a planet where there are suitable conditions for life to exist.
He pointed out that Proxima Centauri b was the closest exoplanet to our solar system (just 4.2 light-years away) but as it revolved very close to a red dwarf star Proxima Centauri, which gave out a faint light, radiations and stellar winds, the conditions on the exoplanet were unlike that of KOI-456.O4, which seemed more suitable.
With Kepler 160, the star of the new planet candidate having temperatures at 5,200 degrees Celsius just 300 degrees less than the Sun and luminosity and colour of visible light almost like the Sun, scientists believe that KOI-456.04 surface is most likely to have an environment conducive to life.
Kepler 160 with a radius of 1.1 solar radii, emits visible light like the sun unlike most other exoplanets having Red Dwarf star as their sun which gives out faint light and emit infrared radiation.
Exoplanets or planets outside the solar system rotating around stars other than the sun are difficult to locate because their light is very faint compared to their host star when seen from Earth.
Just about dozen-odd exoplanets are probably habitable of the more than 4,000 exoplanets discovered so far by space telescopes such as CoRoT, Kepler, and TESS (Transitting Exoplanet Survey Satellite). Most of the exoplanets discovered have been found to be either gas giants, spheres of hot lava, or frozen globes.
Dr. Heller himself is already credited with the discovery of 18 sub-to super-Earth-sized planets in the data of NASA’s Kepler Space Telescope. But it is his 19th find of the earth like planet KOI-456.04 around the sun-like star Kepler – 160 which is creating all the excitement throughout the world.
According to one estimate, there could be 40 billion earth-sized planets orbiting habitable zones of sun-like stars and Red Dwarf stars within the Milky Way galaxy itself.
Detecting these planets is extremely difficult because the host star’s light is the main source of illumination in which it is difficult to locate the planet from which a faint light may come and that too is not seen in the long distance.
There are two primary methods of detection of planets, one is Transit method where scientists measure a star’s brightness and wait for that brightness to dim as a planet passes in front of it, the second is Doppler method where scientists look for changes in the spectrum of light caused by interactions between the gravity of the star and the gravity of a nearby planet.
In the Transit method, a lot more planets can be discovered (Kepler Space Telescope is claimed to track brightness on 200,000 stars at once) where brightness is checked but then it can only spot a planet when it crosses the star. In the Doppler method, though the only light spectrum of an individual star can be studied planets can be found which may have been missed in the transit method.
Dr. Heller said that they did not spend time to go over all the recorded measurements from about 1,50,000 stars found by Kepler Space Telescope to locate planets but focused on 517 stars around which transiting planets had already been discovered by Kepler.
They looked for additional planets that might have been missed so far and were able to locate planetary candidate KOI-456.04 around the sun-like star Kepler – 160, which already had three more planets revolving around it. These planets are much bigger than Earth and being in close orbits around their star, do not have temperatures that would allow the possibility of life.
Most of the exoplanets found so far including that from the Kepler mission have been much larger than the Earth in size and orbiting too close to their stars to make the temperature on the planet too high for liquid surface water to exist.
The exoplanets which are earth-sized have been found to have stars that orbit around Red Dwarf stars, which do not emit visible light but infrared radiation.
Earth has water because it is in the right distance from the Sun to have surface temperatures required for the existence of liquid water. Scientists believe that KOI-456.04 may also have water and atmosphere to sustain life. The amount of light received from Kepler 160, its host star is about 93 percent of the sunlight received on Earth.
The confirmation may be possible with the world’s largest telescopes like Thirty Meter Telescope and James Webb Space telescope being ready to start functioning.
According to Deputy Director, Dr. Subhendu Pattnaik, Pathani Samanta Planetarium, Bhubaneswar, “There is nothing much to be very excited for such a finding for a common man, as it is at a distance of 3000 light-years away from us. One light-year is the distance that light travels in one year. Light speed is 3 lakh kilometer per second and at present, our rockets are capable of traveling at less than 1% of the speed of light. Even if we travel at the speed of light it will take us 3000 years to reach that planet. So even if we find a purely Earth-like planet it will only be our academic interest and not going to have any immediate effect on our civilisation. These findings will be very useful for further understanding of our universe and finding habitable places outside our solar system.’
