In our solar system, there are all kinds of objects: planets, comets, asteroids. Some are hot, some are cold. Some are made of gases, others rock, others ice. A few—like Earth—even have liquid on their surface. But there's one thing that is very rare indeed: a body made entirely of metal. Introducing 16 Psyche, our solar system's only known all-metal asteroid. NASA has just confirmed that it plans to send a probe there by 2023. And what will it hope to find? The secrets of our own planet's insides. Check it out!
It's not that metals don't exist in space. They definitely do. Our own planet has a large core made of metal (iron and nickel), as do the other planets. But that's the point. This metal is usually hidden deep inside the planet. (That's why we need to mine—or dig into the ground—to get many of our metals.) So while scientists can use tests to determine what a planet's core is like, it's impossible to dig far enough down to actually visit the core.
What a shame. If only there was some way to take the core out of the planet, right? Actually, please don't do that, the Earth would collapse! Yikes! Besides, that's where Psyche comes in. Essentially, Psyche (made of iron and nickel) is like that core removed from within a planet. So much so that the leading theory on how the asteroid came to be is that it is the core of a planet.
Surface blasted off
So how did Psyche "get out" of its original planet? Scientists believe that in the early days of our solar system, this planet (which would've been about the size of Mars today) was bombarded heavily by asteroids and maybe even collisions with larger bodies, like another planet. These collisions were so severe that the surface of the planet was essentially blasted off of its core. All that was left was its super tough metal insides.
Now NASA wants to send a probe to visit Psyche to see if this is true. If scientists are right, it would give them a chance to learn a lot: about the cores of other planets, including Earth, and about the birth of the solar system itself. Scientists believe that Psyche has been around since the Sun was only 10 million years old. That might seem old to you, but if the Sun was as old as you, 10 million years old would be like when you were only a couple months old!
Between this and the mission to Ceres that we wrote about in November, it just goes to show: there's a lot more to the asteroid belt than a bunch of rocks floating through space!