Evidence Continues To Mount For Ninth Planet

Artist's concept of the hypothetical "Planet Nine." Could it have moons? Credit: NASA/JPL-Caltech/Robert Hurt

Ever since its existence was first proposed, the evidence for Planet 9 continues to mount. But of course, said evidence has been entirely indirect, consisting mostly of studies that show how the orbits of Trans-Neptunian Objects (TNOs) are consistent with a large object crossing their path. However, evidence is also emerging that comes from the center of the Solar System itself.

This latest line of evidence comes from Caltech, where researchers Elizabeth Bailey, Konstantin Batygin, and Michael E. Brown (the latter of whom were the ones who first proposed Planet 9’s existence) have published a new study linking solar obliquity to the existence of Planet 9. Essentially, they claim that the axial tilt of the Sun (6°) could be due to the gravitational influence a large planet with an extreme orbit.

To recap, the issue of Planet was first raised in 2014 by astronomers Scott Sheppard and Chadwick Trujillo. Noting the similarities in the orbits of distant Trans-Neptunian Objects (TNOs), they postulated that a massive object was likely influencing them. This was followed in 2016 by Konstantin Batygin and Michael E. Brown of Caltech suggesting that an undiscovered planet was the culprit.

The orbits of several KBOs provide indications about the possible existence of Planet 9. Credit: Caltech/R. Hurt (IPAC)
The orbits of several KBOs provide indications about the possible existence of Planet 9. Credit: Caltech/R. Hurt (IPAC)

Calling this body Planet 9, they speculated that it had a mass 10 times greater than that of Earth, and took 20,000 years to complete a single orbit of our Sun. They also speculated that its orbit was tilted relative to the other planets of our Solar System, and extremely eccentric. And little by little, examinations of other Solar bodies have shown that Planet 9 is likely out there.

For the sake of their study – “Solar Obliquity Induced by Planet Nine“, which was recently published in the Astrophysical Journal – the research team (led by Bailey) looked to the obliquity of the Sun. As they state in their paper, the six-degree axial tilt of the Sun can only be explained in one of two ways – either as a result of an asymmetry that was present during the formation of Solar System, or because of an external source of gravity.

To test this hypothesis, Bailey, Batygin and Brown used an analytic model to test how interactions between Planet 9 and the rest of the Solar System would effect their orbits over the course of the last 4.5 billion years. As Elizabeth Bailey, a graduate student at Caltech’s Division of Geological and Planetary Sciences and the lead author on the paper, told Universe Today via email:

“We simulated the solar system’s motion. Planet 9 forces the solar system to slowly wobble. If Planet 9 is out there, we are in the process of wobbling right now, as we speak! But it happens very slowly, a few degrees tilt per billion years. Meanwhile the sun is not wobbling much,  so it looks like the sun is tilted. A range of Planet 9 parameters cause exactly the configuration of the sun that we see today.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign
Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

In the end, they concluded that the Sun’s obliquity could only be explained by the influence of giant planet with an extreme orbit, one that is consistent with the characteristics attributed to Planet 9. In other words, the existence of Planet 9 offers an explanation for the Sun’s peculiar behavior, something which has remained a mystery until now.

“Planet Nine was first hypothesized because the orbits of objects in the outer reaches of the solar system are confined in physical space,” said Bailey. “Those orbits would be all over the place unless something is currently stopping them. The only explanation so far is Planet Nine. For over 150 years, people have wondered why the sun is tilted. Personally I’d say that Planet 9 offers the first satisfying explanation. If it exists, it tilted the sun.”

In addition, the subject of Planet 9 was also raised at the joint 48th meeting of the American Astronomical Society’s Division for Planetary Sciences and 11th European Planetary Science Congress, which took place from Oct 16th to 21st in Pasadena, California. During the course of the meeting, researchers from Arizona University shared the results of their own study, which was published back in August.

The Arizona research team was led by Renu Malhotra, a Regents’ Professor of Planetary Sciences in the University of Arizona’s Lunar and Planetary Lab. For the sake of their study, titled “Corralling a Distant Planet with Extreme Resonant Kuiper Belt Objects“, they examined the orbital patterns of four extreme Kuiper Belt Objects (KBOs), which have the longest orbital periods of any known objects.

Artist's impression of the the possible Planet 9 at the edge of the Solar System. Credit: Robin Dienel/Carnegie Science
Artist’s impression of the the possible Planet 9 at the edge of the Solar System. Credit: Robin Dienel/Carnegie Science

According to their calculations, the presence of a massive planet – one that would complete an orbit around the Sun every 17,117 years, and at an average distance (semimajor axis) of 665 AU – would explain the orbital pattern of these four objects. These results were consistent with the estimates concerning the orbital period of Planet 9, its orbital path, and it mass.

“We analyzed the data of these most distant Kuiper Belt objects,” Malhotra said, “and noticed something peculiar, suggesting they were in some kind of resonances with an unseen planet… Our paper provides more specific estimates for the mass and orbit that this planet would have, and, more importantly, constraints on its current position within its orbit.”

Looks like Planet 9’s days of hiding in the outer Solar System may be numbered!

Further Reading: arXiv, Caltech, Europlanet

Paddleboat Mission to Titan Proposed

Three concepts for the TALISE boat mission to Titan: screw propelled (left), paddle wheels (center) and inflatable wheels (right). Credit: Urdampilleta, et al.

Is sending a boat to Titan an outlandish idea? Maybe, said a group of European scientists and engineers, but they’re working on a plan. The Titan Lake In-situ Sampling Propelled Explorer (TALISE) proposes a sending an instrument-laden boat-probe to Saturn’s largest moon that could be propelled by paddles, inflatable wheels or screws. The probe would land in the middle of Ligeia Mare – Titan’s biggest lake, near the moon’s north pole — then set sail for the coast, taking scientific measurements along the way.

“The main innovation in TALISE is the propulsion system,” says Igone Urdampilleta from SENER, an engineering company in Spain and a member of the TALISE team. “This allows the probe to move, under control, from the landing site in the lake, to the closest shore. The displacement capability would achieve the obtaining of liquid and solid samples from several scientific interesting locations on Titan’s surface such as the landing place, along the route towards the shore and finally at the shoreline.”

In a presentation at the European Planetary Science Congress on September 27, 2012, the TALISE team says that since Titan has a thick atmosphere, a diameter between that of Earth and the planet Mercury, and a network of seas, lakes and rivers, it is in many respects more like a planet than a moon.

And it’s time to go there and do a little in-situ science. The principle objective of the mission would be to characterize Titan’s environment and the chemical composition of the lakes and terrain.

While the Cassini-Huygens mission landed the Huygens probe on Titan in 2005, it transmitted data for only about 90 minutes after touchdown. The TALISE mission would last six months to a year.

Images from the Cassini mission show river networks draining into the lakes in Titan’s north polar region. Credit: NASA/JPL/USGS

The Cassini orbiter has confirmed that lakes, seas and rivers of liquid hydrocarbons cover much of the Titan’s northern hemisphere, and these hydrocarbons may rain down on the surface, forming the frigid liquid bodies. With surface temperature at -178 degrees Celsius (-289 degrees Fahrenheit), Titan’s environment is too cold for life as we may know it, but its environment, rich in the building blocks of life, is of great interest to astrobiologists, the team said.

“The chemical composition of the lakes of Titan is still not well determined,” the TALISE team wrote in their abstract. “The detection of other compounds and the investigation of influence of both, photochemistry and the atmosphere on the chemical composition of liquids of Titan lakes remain challenging in the absence of in situ measurements. Therefore, it is next step to understand the Titan lakes environment, its relationship with the climate behavior, the surrounding solid substrate and analyze the organic inventory including the possibility of prebiotic compounds.”

The actual configuration of the boat is still under consideration, and they are considering various in-situ propulsion methods through the liquid hydrocarbon seas. In addition to paddle wheels, screw propulsion and inflatable wheels, they are also looking at tank wheels, air propeller, liquid propeller and a hovercraft design.

The TALISE concept is being developed as a partnership between SENER and the Centro de Astrobiología in Madrid, Spain, and the mission is still in the very early stages of feasibility studies and preliminary mission architecture design, but they are hoping to be ready for a future space science mission call for proposals.

Sources: EPSC, TALISE team abstract

A New, Automatic 3-D Moon

Korolev lobate scarp on the Moon, in 3-D. Lobate scarps, a type of cliff,are found mostly in the highlands on the Moon, and are relatively small and young. Credit: NASA/GSFC/Arizona State University.

Who doesn’t love 3-D images, especially of objects in space? But creating them can be a bit time-consuming for scientists, especially for images from orbiting spacecraft like the Lunar Reconnaissance Orbiter that takes images from just one angle at a time. Usually, it is “amateur” enthusiasts who take the time to find and combine images from different orbital passes to create rich, 3-D views.

But now, scientists at the University of Arizona and Arizona State University have developed a new automatic “brain” — a new automatic processing system that aligns and adjusts images from LRO, and combines them into images that can be viewed using standard red-cyan 3D glasses.

Alpes Sinuous Rille, an ancient channel formed as massive eruptions of very fluid lava poured across the surface of the Moon. Credit: NASA/GSFC/Arizona State University

Human vision sees in three dimensions because our eyes are set slightly apart and see the world from two different angles at once. Our brain then interprets the two images and combines them into a single three dimensional view.

It’s fairly easy to create 3-D views from the Mars rovers like Curiosity and Opportunity, because they have mast cameras and navigation cameras which operate in pairs to provide stereo views of the Martian surface.

Ancient radial scars of ejecta extend out from the Orientale basin for hundreds of kilometers and consist of aligned craters and massive dune-like forms. They formed as streamers of lunar rock thrown out from the Orientale impact and crashed back to the surface. Credit: NASA/GSFC/Arizona State University

But LRO orbits high above the Moon’s surface, and can see from only one angle at one time. However, images taken in different orbits, from different angles can be combined together to reconstruct a view in three dimensions.

And this new system can automatically combine the disparate shots together. The images here are a sample of what the team has created so far.

This ‘brain’ is provided by a new initiative, presented by team member Sarah Mattson (University of Arizona) to the European Planetary Science Congress on 25 September. The team have developed an This type of image is known as an anaglyph.

“Anaglyphs are used to better understand the 3D structure of the lunar surface,” said Sarah Mattson from the University of Arizona and LRO team member. “This visualization is extremely helpful to scientists in understanding the sequence and structures on the surface of the Moon in a qualitative way. LROC NAC anaglyEuropean Planetary Science Congress on 25 September. LROC NAC anaglyphs will also make detailed images of surface of the Moon accessible in 3D to the general public.”

The Lunar Reconnaissance Orbiter Camera – Narrow Angle Camera (LROC NAC) has acquired hundreds of stereo pairs of the lunar surface, and is acquiring more as the mission progresses. The LROC NAC anaglyphs make lunar features such as craters, volcanic flows, lava tubes and tectonic features jump out in 3D. The anaglyphs will be released through the LROC website as they become available.

Mattson presented the new system at the European Planetary Science Congress on September 25.