Rejoice, for a rogue planet has been detected pottering about 20 light-years from Earth. Although we’ve detected worlds like this before, this is the first time that a planetary-mass object has been spotted beyond our Solar System using a radio telescope, the Very Large Array (VLA) in New Mexico.
At this point, I can hear you all asking: What the hell is a rogue planet? Referred to using all manners of monikers, from wandering planet to orphan planet, a rogue planet is simply one without a star.
There are a range of ways these take shape. From their original one or multi-star planetary systems, these worlds were dragged away by, say, another passing star, or perhaps they were ejected as a protoplanet during the system's early days of piecing itself together.
Although some estimates place the number of rogue planets in our galaxy as high as 100,000 for each star, a 2017 study concluded that there’s probably around one for every four stars. Many of them appear to be gas giants, and some are so huge that their mass lingers between that of Jupiter and the smallest stars.
Unlike their stellar furnace compatriots, these titans aren’t massive enough for a runaway nuclear fusion of their hydrogen and helium to take place. As such, they remain almost-stars and are termed “brown dwarfs”.
The fact that they are often still contracting under their own mass explains why they give off their own heat signature. Per The Astrophysical Journal, this new rogue world has a mass that just about allows it to build up a decent amount of gas pressure, which partly explains why its surface temperature is around 825°C (1,500°F)
SIMP J01365663+0933473, this rogue planet under the microscope, was first spotted using the VLA in 2016, along with four others. It was first thought to be both massive and ancient, but a separate research team re-checked the data in 2017 and found something remarkable.