The search for a planet beyond Pluto.

While I am not an astronomer, nor do I play one on television, I rebel against the whole "dwarf planet" phenomenon. Pluto may be small, and part of a cluster with other small worlds, but it is  a sphere not some planetary fragment like Ceres.

The short version: I think it's a planet and will be officially designated as such one day.

Anyway, the search for the "next planet" has been ongoing since Clyde Tombaugh found Pluto.

Here's the latest update about the search from The Guardian:

These days, [astronomer Scott] Sheppard can regularly be found using Japan’s Subaru telescope on Mauna Kea, Hawaii, patiently scouring the sky for more evidence of Planet 9, maybe even hoping that he sees the planet itself. The scale of the task is enormous. It really is like looking for the proverbial needle in a haystack. The planet – if it is even there – is very faint and the sky is very large. But help is on its way in the form of the Rubin observatory.

Rubin is a monster that will devour the sky. Whereas most telescopes would take months or years to survey the whole sky, Rubin will do it in just three nights. Then do it again and again and again to see what’s changed and so catch the moving objects.

Construction is nearing completion, and the telescope is set to open its giant eye for the first time in 2020. Commissioning and tweaking will then take another couple of years.

“That survey is going to change solar system science as we know it,” says Sheppard. And if Planet 9 is out there, Rubin should see it.

“We can detect an Earth-mass planet at around 1000 AU,” says Meg Schwamb, of Queen’s University Belfast, who co-chairs the Rubin observatory’s solar system science collaboration. That puts Sheppard’s world easily within its sights. “If others haven’t seen Planet 9 before our survey starts then, I think, all eyes are on the Rubin observatory,” says Schwamb.

Even if the telescope fails to see the planet directly, it will detect many more distant mini-worlds that can all be use to triangulate the planet’s position more precisely, thus helping to narrow the search area. And if Planet 9 really is out there, then the consequences will be huge.

Astronomers think that the solar system formed in a disc of matter surrounding the sun. That matter condensed into smaller bodies, which then collided to form larger ones. At the end of this process, the planets were born. But the matter in this disc thins out further from the sun, meaning there is not enough raw material to form a large planet in the distant solar system.