Astronomers, who are searching for signs of alien life, have observed the transit of an Earth-like extrasolar planet which is potentially habitable. The planet is located 150 light-years away from the Earth. A transit takes place when a planet passes in front of its parent star. During transit, the planet blocks a small amount of light from the star like the planet’s shadow.
How the observation was done?
The transit of K2-3d was observed by the researchers, including those from the National Astronomical Observatory of Japan (NAOJ) and the University of Tokyo. The MuSCAT instrument on the Okayama Astrophysical Observatory 188-cm telescope was used to observe the planet.
The next generation of telescopes like TMT may play a significant role in helping the scientists search the planet’s atmosphere for molecules related to life, such as oxygen.
Flaws in previous space telescope observations
Previous space telescope observations were not capable of calculating the orbital period of the planet precisely. It makes the task of scientists to predict the exact times of future transits more daunting.
This research group has now successfully measured the orbital period of the planet with a high precision of about 18 seconds. This has also greatly improved the forecast accuracy for future transit times.
Astronomers will now be able to know exactly when to look out for the transits using the next generation of telescopes. This research result is also an important step towards the search for extraterrestrial life in the future.
What is K2-3d?
NASA K2 mission had discovered the K2-3d, an extrasolar planet. The planet, which is located 150 light-years away, is 1.5 times the size of the Earth. The host star of the planet is half the size of the Sun. The planet orbits the star with a period of about 45 days.
Compared to the Earth, the planet orbits close to its host star (about 1/5 of the Earth-Sun distance). However, because the temperature of the host star is lower than that of the Sun, calculations show that this is the right distance for the planet to have a relatively warm climate like the Earth’s.
What makes K2-3d potentially habitable?
Liquid water could possibly exist on the surface of the K2-3d planet. This raises the tantalising possibility of extraterrestrial life.
K2-3d’s orbit is aligned so that as seen from Earth, it transits (passes in front of) its host star. This causes, short, periodic decreases in the star’s brightness, as the planet blocks some of the star’s light.
This alignment enables researchers to probe the atmospheric composition of these planets by precise measurement of the amount of blocked starlight at different wavelengths.
Since it is closer to Earth and its host star is brighter, K2-3d is a more interesting candidate for detailed follow-up studies.
Potentially habitable planets discovered so far
About 30 potentially habitable planets that also have transiting orbits were discovered by the NASA Kepler mission, but most of these planets orbit fainter, more distant stars.
(With inputs from PTI)