Early Earth wasn't so much a planet as a donut-shaped formation of vaporized rock called synestia.
Earth, like other rocky planets, had quite a violent infancy. Scientists say that early in our planet's existence, Earth crashed into an object called Theia, which was roughly the size of Mars. Huge, violent impacts like this have the capability to completely vaporize entire planets.
Donut-like disks of vaporized rock form as a result of these impacts. Planets turn into spinning gas blobs with edges that spin faster than the inner core. These blobs form into a shape reminiscent of a donut, or—more accurately—a red blood cell. The blob flattens down from the edges towards the core.
Scientists coined the term “synestia” by taking two Greek terms. “Syn” means “together” in Greek, while “Hestia” is the ancient Greek goddess of the hearth, home, and structure. “Synestia”, according to the people who coined it, thus means “connected structure”.
The funny thing about a synestia—other than its shape—is that no one has ever observed one. Its existence is theoretical at this point. With the use of simulations, researchers were able to theorize the existence of synestias as a stage in a planet's early days.
There have been other studies that have theorized that collisions and impacts form a ring of debris around a planet. A synestia, however, isn't like this at all. It has no surface, be it solid nor liquid. The whole thing is also quite larger than the planet it used to be.
According to a new study, early Earth may have been a synestia at some point. However, it probably didn't stay in that state for too long. Had the Earth undergone a period of synestia, it would have lasted for only about a century. Scientists say that when the Earth in its synestia stage lost enough heat, it reverted back to its solid form.
The researchers claim that many, if not most, planets go through a synestia stage. Though synestias are theoretical, at least for now, there's a chance that astronomers may spot one in other galaxies. Young star systems are also prime candidates in the search for an actual synestia.
Where exactly should astronomers look, though? Planets that are close to their star may be the astronomers' best bet. The outer part of these planets would most likely be very hot. If the planet also spins quite quickly, there's a chance that it may be a synestia.
For now, the researchers are creating a model of how early Earth went through its synestia stage.
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