Some 4.6 billion years ago as rock and ice particles swirling around the young sun collided and merged snowballing to produce ever larger planetary building blocks. In violent pileups, they smashed together to create planets, including the infant Earth. In the turmoil, another body, as big as Mars, struck our planet with the energy of trillions of atomic bombs, enough to melt it all the way through.
Most of the impact was swallowed up in the bottomless magma ocean it created. But the collision also flung a small world’s worth of vaporized rock into orbit. Even so, our planet remained an alien world for the next 700 million years; scientists call this time the Hadean, after the Greek underworld. Gasses hissed from the cooling rock—carbon dioxide, nitrogen, water vapor, and others enveloping the planet in a scalding atmosphere devoid of oxygen.
As the temperature dropped further, the steam condensed into rain that tells in primordial monsoons and filled the ocean basins. These first oceans may have been short-lived. Space rubble left over from the birth of the planets chunks of rock tens to hundreds of miles across bombarded Earth throughout the Hadean. The greatest impacts might have boiled the oceans away, forcing the process of cooling and condensation to begin again. By 3.8 billion years ago the impacts relented. Liquid water could persist. About that time, perhaps in the oceans, lifeless chemical reactions crossed a threshold, producing molecules involved enough to reproduce themselves and evolve toward greater complexity.
Life was on a road that led, as early as 3.5 billion years ago, to single-celled, blue-green cyanobacteria that flourished in the sunlit parts of the oceans. By the trillions, these microscopic organisms transformed the planet. They captured the energy of the sun to make food, releasing oxygen as a waste product. Little by little they turned the atmosphere into breathable air, opening the way to the diversity of life that followed. Earth began to form over 4.6 billion years ago from the same cloud of gas (mostly hydrogen and helium) and interstellar dust that formed our sun, the rest of the solar system and even our galaxy. In fact, Earth is still forming and cooling from the galactic implosion that created the other stars and planetary systems in our galaxy. This process began about 13.6 billion years ago when the Milky Way Galaxy began to form.
Today, Earth is the only planet we know of that can support life. This is a surprising fact, considering that it is made out of the same matter as other planets in our solar system, was formed at the same time and through the same processes as every other planet, and gets its energy from the sun. Physicist Professor Stephen Hawking says that mankind could be wiped out by our own creations within the next 100 years. He predicts that as we rush to develop new technologies to improve our life, the threats to the human race will increase until some Global cataclysm is virtually inevitable. Thus, the need and the search for life outside our solar system has been brought to our cosmic doorstep with the discovery of an apparently rocky planet orbiting the nearest star to our sun.
The planet is 4.2 light-years ( that is about 25 trillion miles) away from Earth and is named as Proxima b the new world has sparked a flurry of excitement among astrophysicists with the idea that it might be similar in crucial respects to Earth The planet has other characteristics that could affect its potential to host life. The planet is still within the potentially habitable zone (the place where temperatures are just right for liquid water to exist) of its star because Proxima Centauri is a type of red dwarf known as an M dwarf – a smaller, cooler, dimmer type of star than our yellow dwarf sun. The planet orbits an (M-type) red dwarf star named Proxima Centauri. The star has a mass of 0.12 M☉ and a radius of 0.14 R☉ It has a surface temperature of 3042 K and is 4.85 billion years old.
In comparison, the Sun is 4.6 billion years old and has a surface temperature of 5778 K. Proxima Centauri rotates once roughly every 83 days and has a luminosity about 0.0015 L☉. The star is rich in metals, something not commonly found in low-mass stars like Proxima. Its metallicity ([Fe/H]) is 0.21, or 1.62 times the amount found in the Sun’s atmosphere.
Proxima b, despite its closeness to the star, receives less warmth than Earth, but enough that water could flow on the surface. Whether the planet has liquid water or an atmosphere is “pure speculation at this point,” Dr. Anglada-Escudé said in a news conference. However, “potentially habitable” doesn’t mean “habitable,” and it doesn’t mean “inhabited.” It’s possible that this world is a barren wasteland similar to Mars or a toxic planet like Venus. But life on Proxima b isn’t completely out of the question just yet. “Finding out that the nearest star to the sun hosts not just a planet, not just an Earth-sized planet, but one which is in the right location that it could support life, and there are a lot of caveats there really underscores that not only are planets very common in our galaxy but potentially habitable planets are common,” says Eamonn Kerins who is an astrophysicist.
While its mass is thought to be at least 1.3 times that of the Earth, its size, and hence density, is unknown, meaning that scientists can only make an educated guess that it is likely to be rocky based on the types of exoplanets that have previously been detected around other small stars. It orbits its star in just 11.2 days, and its gravitational pull and the close orbit suggests that the rotation of the planet would probably be gravitationally locked by the sun’s pull. Just as the same side of the moon always faces Earth, one side of Proxima b is likely to be eternally bright, always facing the star, while the other is ever dark.
The astronomers don’t know if Proxima b transits yet. They found this planet using the technique called the radial velocity method which involves studying the very tiny movements in the world’s host star, Proxima Centauri. When Proxima b orbits around Proxima Centauri, the planet’s gravity tugs on the star and causes it to wobble slightly. Astronomers confirmed Proxima B’s existence by studying these wobbles. The first indications of the exoplanet were found in 2013 by Mikko Tuomi from archival observation data.
To confirm the possible discovery, the European Southern Observatory launched the Pale Red Do project in January 2016. Proxima Centauri is a fickle star. It’s a type of red dwarf known as a flare star. That means every so often, Proxima Centauri flares and increases in brightness. This flaring is going to make it very hard to figure out where Proxima b is, even if it does transit.
Lead author Guillem Anglada-Escude, an astronomer at the Queen Mary University of London, described the finding as the “experience of a lifetime. “It is not unlikely that this planet is quite similar to Earth. The striking finding of this, of course, is that this system is so close to our Earth and solar system,” said Ansgar Reiners, a German scientist who is among the research’s co-authors. However, it is not clear if the planet has an atmosphere or if it contains water, but “the existence is plausible”, he added. There are hints of perhaps another planet, maybe more, but those hints are still ambiguous, the scientists said.The discovery could provide the impetus for planet-finding telescopes. Ruslan Belikov of the NASA Ames Research Center in Mountain View, Calif., has proposed a small space telescope costing less than $175 million dedicated to the search for planets in Alpha Centauri.
While it would not be powerful enough to spot Proxima b, its existence would give more confidence that terrestrial planets also orbit the two sun-like stars there.“It just raises the public awareness there’s a new world just next door,” Dr. Belikov said. “It’s a paradigm shift in people’s minds.” Earth being the only planet that provides oxygen from trees, water, food, and environment and a place to stay and live is crucial. It is unique and therefore for the Humans to survive, it is imperative for us all to look after it and to protect it in every possible way.