Launched by the National Aeronautics and Space Administration (NASA) in 2009, the Kepler telescope, named after the astronomer Johannes Kepler, is a telescope aboard a space observatory in a heliocentric orbit trailing Earth. With a much higher field of vision than the Hubble telescope, the telescope is designed to survey a portion of the Milky Way with the specific objective of determining the properties of planets beyond the Solar System.
The Kepler telescope utilizes a photometer as its sole scientific instrument that monitors the light emitted by distant stars without the refractive interference of the Earth’s atmosphere. The data collected is transmitted to Earth, where it is analyzed to detect the minute dimming of the star’s light as exoplanets – planets other than those of our solar system – pass in between the telescope and the star using a method called doppler spectroscopy. All properties of the planets are analyzed according to the analysis of the properties of the light from the star. The method is able to ascertain properties such as the presence of the planet and its size, a planet’s proximity to and orbit around its star, the minimum number of planets in a star system, the properties of the stars themselves, and certain physical properties of giant-planets close to the star.
For example, using doppler spectroscopy, a method of analyzing wavelengths of the characteristic spectral lines of a light source, one could evaluate the chemical composition of the star based on the spectral signature (representation in the colour spectrum) of the chemical components (Harvard University, 2013). Measuring the chemical composition of the planet involves the readings from when the planet passes in front of the star subtracted from the star’s cumulative chemical composition. However, without empirical evidence that proves the hypotheses conclusively, nothing can be said with absolute certainty about the chemical composition of the exoplanets discovered. With the passage of time, we could hope for a more complete and proven hypotheses of the properties of exoplanets, existence of which are being increasingly revealed by Kepler telescope and more.
One science in particular shall be truly tested if the hope that has been generated from the recent finding of 10 more Earth-like planets in the goldilocks zone is realized – the science of biology –presently unique to Earth, unlike many other scientific laws. The ‘goldilocks zone’ for exoplanets represents its potential habitability as when the planet orbits in such a distance from its star that it can be said to receive just the right amount of energy from its star to be able to support life.
One major stipulation for measuring this zone for scientists is the possibility for the exoplanet to support liquid water. Being too close to the star might cause water to vapourize and being too far could freeze it. In the goldilocks zone, scientists are hoping that the exoplanet might be able to support water – the chemical solvent required by all life on Earth.
(Source : astrobiology.nasa.gov)
However, this can be variable. The recent discovery of liquid methane seas in Saturn’s moon Titan by the spacecraft Cassini, that could cause rain to fall like snowflakes in Titan’s low gravity atmosphere, point towards interesting possibilities. Methane does not naturally occur in a liquid state on earth, but in a gaseous state. Titan’s extremely low temperatures and hydrocarbon atmosphere allows liquid methane seas, and this points towards ways of looking at alien exoplanets.
Out of the planets newly validated by NASA, 550 out of the confirmed 2,335 exoplanets are rocky worlds. Out of these, 21 are worlds where the temperatures based on the energy supplied by the star could be just right for liquid water to be present on the surface (NASA, 2017). This raises the hope for life to evolve on planets such as these. Although there is no method of conclusively proving the presence of life on these planets, there is a theory based on the possibilities for discovering life within the Solar System (A. Strickland, CNN, 2017).
Considering that in the near future, humanity succeeds in finding even microbial life within the Solar System, with NASA’s focus on finding life based on the presence of liquids on planets, the theory proposes that this would open up the possibility that life might indeed be plentiful throughout the universe.
Humanity’s understanding of planetary schematics is progressing steadily with Kepler’s findings. Among its significant discoveries is the exoplanet Kepler-452b in 2014, which scientists expect to be similar to Earth in many respects due to its location within the habitable zone, although it is located about 1,400 light years away from Earth. In April in 2017, scientists discovered a super-Earth, named LHS-1140b, that orbits a red dwarf star and is 40 light years away.
These and more discoveries by telescopes such as the Kepler telescope, are building up a profile of diversity in exoplanets, with previously unknown planet varieties such as super-Earths and mini-Neptunes. Kepler has only explored a tiny patch of the Milky Way called the Cygnus Field – with about 1,50,000 stars (NASA, 2017). Given the about 300 billion stars estimated to be present in the Milky Way, the amazing diversity from the initial observations point towards the fact that the nuances of the universe might be more interesting than could be imagined.