One of the issues that have stalked modern astronomers is the quest of a planet that might contain life. The search for such a celestial body made a significant advance when astronomers discovered the first planet outside the solar system which could have liquid water and habitable temperatures. This is an exoplanet that orbits a red dwarf star named Gliese 581, 20 light years away in the constellation of Libra. Planets orbiting other stars are called exoplanets by astronomers. Initial calculations of the planet so far away suggest it is one-and-a-half times the size of the Earth. The planet’s orbit path brings it 14 times closer to Gliese 581 than the Earth to its star, the Sun. But Gliese 581 burns at only 3,000C, which is half the temperature of the Sun. Thus the new planet probably has temperatures ranging between 0 to 40C. It is also likely to have an atmosphere and liquid ground water. All these factors taken together make the existence of life on this planet within the realms of scientific possibility. But distance makes accurate observations of this exoplanet incredibly difficult. In fact, this exoplanet was detected by observing the change in the velocity of the parent star. Orbiting planets typically cause such changes in velocity.
Scientists are naturally excited by this discovery because in all the 220 exoplanets that astronomers have previously discovered, there has been, what in the scientific jargon is called, the “Goldilocks problem’’. They have been either too hot or too cold or too big and gaseous, like uninhabitable Jupiter. But the new planet appears to fit the bill. Its discovery could also lead to further studies of exoplanets circling stars with low temperatures. The continuous search for Earth-like planets has invariably focused on stars like the Sun and on locating planets the right distance away from the star each orbits. It was only recently suggested as a theory that red dwarf stars could be good sites to track exoplanets with conditions that match those prevailing on Earth. But as Mr Stephen Hawking, arguably the world’s most famous astrophysicist, has quipped, there may be planets like the Earth, but that they will have life on them does not necessarily follow as a corollary. While sceptics and hopefuls among astronomers quarrel about the possibility of life on an exoplanet, it is awesome to ponder that somewhere out there someone may be observing the activities of homo sapiens on planet Earth.