Not everything in the universe has to play by the neatly set down rules of astrophysics—in fact, space is notorious for simply refusing to conform to most of the rules and laws of the universe. For example, the LQG (Large Quasar Group—a vast collection of quasars) goes against the Cosmological Principle because of its sheer size, and since it defies the long-accepted assumption that the universe, when viewed at a considerably large scale, looks the same regardless of where a person observes it from. And there are other bodies in the universe that refuse to abide by the rules governing our world and what lies beyond—rogue planets.
Unlike the planets in the Solar System, rogue planets don’t have a fixed sunrise or sunset—they are just lost, astray and nomadic worlds traveling across the galaxy at no predetermined route. As said by Neil DeGrasse Tyson, an American astrophysicist and cosmologist, “the galaxy has billions of [rogue exoplanets], adrift in perpetual night. They’re orphans, cast away from their mother stars during the chaotic birth of their native solar systems”. Rogue planets aren’t attached to the overwhelming gravitational pull of a star—they simply drift across the universe, becoming more homeless and misplaced with the passage of time.
But how have these nomadic planets come into existence? It has been speculated by astronomers and scientists that rogue planets exist because they had been expelled or ejected by their original stellar systems. As hypothesized by Greg Laughlin, an astrophysicist of the University of California, Santa Cruz, these homeless planets were unable to find a place during the birth of astral systems, due to the initial gravitational instability that was characterized by the beginning of galaxies and planetary systems. In fact, theories are abounding that there was a fifth giant planet in our Solar System, which was thrown out of orbit and out of the Solar System once the other planets established their planetary course—the position, features and state of the ejected planet is still a massive mystery to everyone here on earth.
The first rogue planets were detected in the late 1990s, by a group of Japanese astronomers—when they found evidence that supported the existence of objects whose masses resembles those of planets in the Chameleon Cluster, located approximately 500 light years from the earth. Because of their utter lack of order, rogue planets can prove to be exceedingly difficult to detect. All the same, they can still be found by employing a variety of methods, such as microlensing (the phenomenon in which a star acts as a gravitational lens when it passes in front of a background star, thereby causing the background star light to increase in intensity and bend through a ring-shaped region) and direct imaging. Using infrared radiation is used to detect the presence of a young rogue planet, whereas microlensing is used for the older, cooler astronomical, hurtling bodies.
And what do these rogue planets contain? As said by the astrophysicist Tyson, “Rogue planets are molten at the core, but frozen at the surface. There may be oceans of liquid water in the zone between those extremes. Who knows what might be swimming there?” This stand of his was strengthened by a study conducted by David Stevenson (a scientist from Caltech University), which concluded that if these orphaned planets kept their hydrogen atmosphere, there climate would be sufficiently warm to have liquid water on the planetary surface. So… could these astronomical objects be viable sources of life and breathing existence? Furthermore, the amazing characteristics of these rogue planets are never-ending. As published in a study conducted by Nature, it has been found that the Milky Way Galaxy contains over 400 billion star-less worlds, as well as the fact that these lonely, rogue planets are more common than stars in our galaxy! This realization isn’t only intriguing but also rather startling—since it tells us that humanity is surrounded by billions of orphaned worlds shooting around the universe at inconceivably high speeds. Given this, what would happen if one, or two of them were to derail from their chaotic path, and make a course straight to the Solar System…? These poor, parentless pieces of rock may not be as “innocent” as they initially seem… after all, chaos is rarely synonymous with safety.