Just one week back, an article written by the late British Prime Minister Winston Churchill was rediscovered after several decades. It is not about politics at all, but surprisingly, about the possibility of life on other planets elsewhere in the universe. Today, it is generally accepted that life must have evolved elsewhere in the vast universe and there could be millions of planets teeming with life, even intelligent life and advanced civilizations.
This opinion was bolstered by the discovery of Exoplanets – planets outside our Solar System – more than a decade ago. The space telescope and more advanced ground based telescopes have made this discovery possible. Scientists have not actually seen any of these planets, but they can estimate the existence of planetary systems around stars like our own Sun by analyzing the light coming from them.
The latest discovery seems to be the most promising of them all – no less than three potentially life-harbouring planets just 40 light years away. (That is, if you travel at the speed of light, you will be able reach these planets in just 40 years). In cosmic terms, though, it is just in our neighbourhood.
In the latest discovery, astronomers have found a system of seven Earth-sized planets just 40 light-years away. They were detected as they passed in front of their parent star, the dwarf star TRAPPIST-1. Three of them lie in the habitable zone and could harbour water, increasing the possibility that the system could play host to some form of life.
It has both the largest number of Earth-sized planets yet found, and the largest number of worlds that could support liquid water. This research was presented in a paper entitled “Seven temperate terrestrial planets around the nearby ultra cool dwarf star TRAPPIST-1”, by M. Gillon et al., to appear in the journal Nature.
The astronomers were using the TRAPPIST-South telescope at ESO’s La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their star, have sizes similar to Earth.
Lead author Michaël Gillon of the STAR Institute at the University of Liège in Belgium says: “This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth.”
With just 8% the mass of the Sun, TRAPPIST-1 is very small in stellar terms—only marginally bigger than the planet Jupiter. Co-author Amaury Triaud says “the energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1.”
While all seven planets discovered in the system could potentially have liquid water, the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water on the surface. TRAPPIST-1e, f, and g, however, represent the ultimate prize for planet-hunting astronomers, as they orbit in the star’s habitable zone.
With further observations, the team has confirmed the objects were indeed planets, with similar sizes to Earth and Venus. The two innermost planets orbit the star in 1.5 and 2.4 days, though they receive only four and two times the amount of radiation, respectively, as the Earth receives from the sun.
The third planet may orbit the star in anywhere from four to 73 days, and may receive even less radiation than Earth. Given their size and proximity to their ultra cool star, all three planets may have regions with temperatures well below 400 Kelvin, within a range suitable for sustaining liquid water and life.
The good news is that with the upcoming generation of telescopes, such as, ESO’s European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope, scientists will soon be able to search for water and perhaps even evidence of life on these worlds within our lifetime, say 30-50 years.
These planets are so close, and their star so small, we can study their atmosphere and composition, and further down the road, which is within our generation, assess if they are actually inhabited. “All of these things are achievable, and within reach now. This is a jackpot for the field,” say the scientists involved in the research. It is debatable whether we can actually send a probe to the star system and get back a ”confirmation of water and life” due to the current speed and range limitations of space probes. Our unmanned space probes have currently achieved only around 1/17,000 of the speed of light, which means that it will take an astonishing 700,000 Earth-years to reach Trappist-1.
If the probe were to return to earth, add another 700,000 years. Clearly, it is not a practical solution unless a faster means of propulsion is achieved. Scientists and engineers are working on that aspect and a breakthrough will be made at some point. There is even a suggestion that some of Star-Trek like warp drive could be possible (In the Star Trek TV series and the movie, the USS Enterprise travels at 118 times the speed of light and at such a speed, you will be in Trappist in a flash).
A far more practical solution (for the time being, at least) is to study the planetary system with the existing equipment which are already quite good. With time running out for the Earth due to climate change (and even manmade factors, such as, the possibility of nuclear war), mankind must search for a second home or two. We should search in the cosmic neighbourhood (Mars is a tantalizing possibility but it is in the Solar System itself and subject to the same forces of nature) for habitable worlds which can fall into two categories: Planets that can potentially support life and those that may already harbour some forms of life, even at a microscopic, primordial level. Either one would be acceptable to future explorers looking for a second home. It would be a different matter altogether if alien worlds have advanced civilizations because they could in all likelihood be more advanced than us.
This is most likely to be the holy grail of planet hunting – there could be even more promising candidates out there that can definitely answer the question “is there life elsewhere in the universe?”. In any case, scientists predict we would soon find alien life either through ‘contact’ or by scientific investigations like the ones outlined above. That will definitely mark a new chapter in our history and progress.