There are eight planets in our solar system, as far as we know. But there could be more. Astronomers have been exploring evidence of a possible, but a new study suggests there could be yet another lurking at the distant reaches of the solar system, a potential Planet 10.
The study, due to be published in the Astronomical Journal, has a low-key title: "The curiously warped mean plane of the Kuiper belt." But it has big implications. The Kuiper Belt is a region of the solar system that extends beyond Neptune's orbit. It's full of icy celestial bodies, including dwarf planet Pluto. According to NASA, the area "is probably populated with hundreds of thousands of icy bodies larger than 62 miles (100 km) across and an estimated trillion or more comets."
The researchers looked at the orbital tilts of over 600 icy space-rock Kuiper Belt objects (KBOs) and discovered that KBOs at the outskirts of the belt are tilted differently than would be expected. "In other words, something unknown is warping the average orbital plane of the outer solar system," the University of Arizona noted in a press release this week.
Study co-author Kat Volk of the University of Arizona's Lunar and Planetary Laboratory believes an unseen mass is the most likely explanation for the anomaly. "According to our calculations, something as massive as Mars would be needed to cause the warp that we measured," she says.
The researchers believe Planet 10, if it's out there, would be somewhere between the mass of Mars and Earth.
Could the unexpected inclinations of all these distant KBOs actually be caused by the already hypothesized Planet 9? The researchers say "no." Planet 9, which could be 10 times the mass of Earth, is projected to be too distant to impact these KBOs.
While we've have sent spacecraft to nearby planets such as Mars and Jupiter, the far reaches of the Kuiper belt remain a fairly mysterious place. The limitations of our current telescope technology could make it plenty easy to miss an entire planet lurking out there. The researchers hope the highly advanced Large Synoptic Survey Telescope, scheduled to go into service in 2020, will help answer questions about the existence of Planet 10.
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