Could a massive planet be wandering the far regions of our outer solar system?
Guest speaker Samantha Lawler discusses whether a theoretical planet is “Planet 9 or Planet Nein?” at Nanaimo Astronomy Society’s meeting next week.
Originally from Los Angeles, Lawler received her B.Sc. in astrophysics from California Institute of Technology. She came to Canada to earn her PhD at the University of British Columbia and was a lecturer the University of Victoria. Lawler is a Plaskett Fellow at the National Research Council – Herzberg since 2015.
Her presentation will discuss discoveries surrounding the search for Planet 9.
“Planet 9 is not an actual discovery. It’s a theory that was proposed to explain the orbits of a few Kuiper Belt objects that are kind of strange,” Lawler said. “The theory is that there’s this unseen mass out there that’s affecting the orbits of some of the most distant Kuiper Belt objects.”
The Kuiper Belt, where most comets come from, is a doughnut-shaped cloud of debris encircling the solar system beyond the orbit of Neptune – about 30 AU (30 times the distance from Earth to the sun) to about 50 AU.
Based on observations, if Planet 9 exists it’s estimated to be about five to 10 times Earth’s mass – roughly half as massive as Neptune – and has an elongated orbit that ranges from 400 AU to 800 AU from the sun, an orbit far beyond Neptune, Pluto and the Kuiper Belt.
Proving whether Planet 9 exists, or at least determining what is affecting orbits of Kuiper Belt objects, could lead to better understanding of how our solar system formed, how it compares with others discovered, so far, and potentially predicting the possibility for formation of life on exoplanets.
“Right now we know a lot about the inner parts of some planetary systems and we know a lot about the very distant outer parts of planetary systems, but we don’t know which ones match up to which, so our solar system, we don’t really know if it’s weird or if it’s normal,” Lawler said. “We’re just starting to get to the point where we can, maybe, say something about that … Our solar system’s the only one we know of right now that has life. Does it matter how the planets are configured? Is that really important for life or can life be anywhere? That’s the biggest question in my mind that you could ask.”
The problem with the Planet 9 theory, for Lawler, boils down to “observational biases” that arise when results are derived from observations made on the most distant Kuiper Belt objects, which she said don’t appear to behave as if they’re being influenced by a massive planet.
“I was part of a large international Kuiper Belt survey … and we tried to discover as many Kuiper Belt objects as we could while taking into account all the possible observing biases,” Lawler said. “So when we found an equivalent group of very distant Kuiper Belt objects, we found that they’re consistent with a totally uniform distribution. If Planet 9 exists it should be making these very distant Kuiper Belt orbits cluster so they’re all kind of pointed in the same direction, but we did not find that at all. We found that, when you take into account the observing biases, they’re not clustered.”
Lawler will also talk about other recent discoveries from the Kuiper Belt, including some made by the New Horizons space probe that photographed object 2014 MU69, also known as Ultima Thule. Some images received from the probe have scientists scratching their heads over what it is and where it came from.
“The most recent images that they got back implied that, not only is it shaped like a snowman, but it’s actually flat,” Lawler said. “So it’s not like a snowman. It’s like two pancakes stuck together and nobody, no theorist ever, predicted that.”
Nanaimo Astronomy Society’s March meeting happens March 28, 7-9 p.m. at Beban Park social centre.
To learn more, visit the society’s website at https://www.nanaimoastronomy.com/.