Quest for Planet Nine turns up 'extreme objects' on edge of solar system

Story highlights

  • Newly discovered extreme objects provide further evidence for Planet Nine
  • Researcher hopes to prove within five years whether Planet Nine exists

(CNN)Even with an entire universe to explore, our own solar system is still full of mysteries. Welcome the newest members of our space family, found only recently in the "no man's land" beyond Neptune.

Although they aren't planets, these "extreme objects" hovering on the edge of the solar system just may provide further evidence for one that's rumored to be in our own backyard: Planet Nine.
    For those of you who still feel like Pluto is the ninth planet and was unjustly demoted, hang in there. We'll get to that in a bit.
    The newly discovered objects are most likely made of methane ice and water ice, mixed with some rock, and average 200 to 400 kilometers in diameter. Other than that, the objects are so faint that, from Earth, they only appear as points of light. But the technology used to find them, like telescopes and cameras, has come a long way since such surveys began in 2007.
    "It was like looking through a straw at the sky for very rare objects," said Scott Sheppard, extreme object researcher and astronomer at the Carnegie Institution for Science. But that all changed in 2012. "We went from being able to cover something like a full moon to something that could cover 10 or 12 full moons in a single image. That's why the floodgates have opened for finding these very distant, rare, faint objects."
    The extreme objects were only recently observed using two telescopes in Chile and Hawaii, and the researchers have just submitted them to the International Astronomical Union's Minor Planet Center for official designations.
    Until then, they're stuck with names like 2014 SR349, 2014 FE72 and 2013 FT28, signifying the year they were first observed and a combination of letters and numbers suggesting the time of year. Yeah, those definitely won't be hard to remember in science class.
    An illustration of the orbits of the new and previously known extremely distant solar system objects.

    Searching for Planet Nine

    These discoveries were made by Sheppard and Chadwick Trujillo of Northern Arizona University. This team also announced the discovery of an object with the most distant orbit known in the solar system in 2014, known as 2012 VP113 and nicknamed "Biden."
    Biden, along with other extreme objects beyond Neptune, showed signs of orbiting together in a cluster. This caused the researchers to wonder why, given the fact that the objects were well beyond the range of being influenced by the orbits of the big planets like Jupiter, Saturn, Uranus and Neptune. What were the objects orbiting?
    The researchers believe that there might be a planet 200 times farther from the sun than we are (and five times more distant than Pluto) with an extremely stretched and oblong orbit on the edge of our solar system. It is so massive that it could be as much as 15 times the size of Earth. It's known as Planet Nine or Planet X.
    Sheppard and Trujillo, along with David Tholen at the University of Hawaii, are on a quest to find as many faint, distant objects as they can. The more they find, the more they can narrow the area of sky where Planet Nine might be. With current technology, as well as the next generation of telescopes that will have even more capabilities, Sheppard believes that they could definitively say whether Planet Nine exists in the next five years.
    This may seem like a while, but keep in mind that historically, it has taken about a century or so to find each planet in our solar system, Sheppard said. "If we do find this planet in the next few years, it would be pretty amazing discovery for astronomy. It's kind of mind-blowing to know that something bigger than the Earth is sitting out there in the solar system and we haven't been able to see it."
    So why is this confirmation so difficult? It's the whole forest-for-the-trees concept.
    The search for exoplanets around stars outside our solar system uses specific methods. It's like pointing out specific trees with a drone overhead, compared with peering around the trees in our own forest and trying to count them all.
    A long time ago, when our solar system was forming, this would have been easier because Planet Nine wasn't always living on the edge. It was probably right in the middle of the planets we know so well, Sheppard said.

    A chaotic environment

    If Planet Nine exists, it could be the runt of the giant planets, Sheppard said.
    "I think one of the biggest things we've realized in the last 10 years is that the giant planets didn't form where we see them today. They actually moved around quite a bit and pushed each other around," he said.
    Where massive planets like Jupiter and Saturn exist now, there was a a rich area for forming planets to feed on things like ice. Planets like Neptune and Uranus are smaller because they were pushed away from this region.
    Planet Nine was probably forming in that region and grew to be several Earth masses in size, and then it got close to one of the giant planets and was thrown out into the outer solar system, Sheppard said. That would explain its orbit, which wasn't able to form in a neat circle and instead formed in an a chaotic environment.
    One of the extreme objects in this discovery is the Oort Cloud, the first to be observed so far away. It was also most likely ejected from the area where planets formed. It is so far out that it is barely bound to the sun gravitationally, and research suggests that this is where comets come from.
    But even with these new extreme objects, Pluto is still important and holds a key lesson about the fact that we're still learning the ways of our solar system.
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    "People love Pluto," Sheppard said. "It's still the king of its domain. If you want to call it a dwarf planet, it's the biggest dwarf planet known. To me and most astronomers, we're more interested in how it got there, what it can tell us about the solar system and how things form. It's great for kids to understand that we don't know everything. You could become an astronomer and discover really cool things, because we haven't found everything yet.
    "And right now," Sheppard said, "it's a golden age for the discovery of these small distant objects that could possibly lead us to this really big object."