In January and February 2016, I wrote about Planet Nine (or Planet X, George, Jehoshaphat, or Planet of the Apes, depending your preference), the Neptune-sized world believed to be orbiting the sun on the very edge of the solar system in a highly eccentric orbit. Since then, the search for this mysterious world has continued, and while it has yet to be located, evidence that it exists has been mounting. Not only that, but astronomers now believe it might explain why the solar system is “tipped”.
The Hunt started after Mike Brown, a leading planetary astronomer at the California Institute of Technology (Caltech), and his colleague Konstantin Batygin developed a computer model which showed that the very eccentric orbits of six Trans-Neptunian Objects (TNOs) located in what is called the scattered disk, a sparsely populated region of space between 30 100 AU from the sun, overlapping with the Kuiper belt, could have been due to the influence of a massive, distant planet. At the time, they noted that if the model was correct, other TNOs would likely occupy equally distinct orbits.
At the joint European Planetary Science Congress (EPSC) and American Astronomical Society’s Division for Planetary Sciences (DPS) in October, it was revealed more TNOs fitting the model have been discovered over the past several months. Two of them, 2013 FT28 and 2014 SR349, precisely fit the same type of orbit seen the original six objects used by Brown and Batygin model. Five more have been found in orbits which are effective perpendicular to Planet Nine’s believed orbit around the Sun, something predicted by the computer model.
All of this is helping to narrow down Planet Nine’s potential orbit around the Sun, and the arc of that orbit where it might be found. So much so that Batygin, Brown have teamed with original proponents for Planet Nine Chad Trujillo and Scott Sheppard to use the 8-metre Subaru Telescope atop Mauna Kea in Hawaii to carry out a search of the night sky. Sheppard and Trujillo are also using two telescopes in Chile to search the possible sweep of the planet through the southern hemisphere’s night sky. And they are not alone.
Also at the planetary conference, graduate student Elizabeth Bailey, using Brown and Batygin’s data presented a paper proposing how the odd tilt to the solar system’s major planets relative to the Sun might be due to Planet Nine.
With the exceptional of Mercury, all the major planets in the solar system orbit along a plane tilted by about six degrees from the Sun’s equator. This suggests either the Sun was somehow tipped on its axis in the past, or the planets have been pulled from their original alignment along the Sun’s equatorial plane. Of these two ideas, the preferred option has been for exotic interactions between the early Sun’s magnetic field and the primordial disk of gas surrounding it, inclining the latter, which then formed the planets. However, Bailey’s simulations suggest that a large body occupying Planet Nine’s predicted orbit could have had sufficient influence on the Sun over some 4 billion years to have slowly tipped it over by six degrees. Bailey’s hypothesis was supported by a Brazilian team of astronomers, who used a different analytical method while working independently from her, and reached the same conclusion.
Even so, some remain sceptical that the mysterious world exists. “I give it about a 1% chance of turning out to be real,” says astronomer JJ Kavelaars, of the Dominion Astrophysical Observatory in Victoria, Canada. Interestingly, his fellow researcher and collaborator Cory Shankman, has created models with the exact orbits of the original six TNOs used by Brown and Batygin, and found that a massive planet would not maintain their tell-tale clustering for long periods.
Thus, the search for the solar system’s mysterious Planet Nine, continues.
ETs Phone Home?
Are aliens sending signals using their own stars? That’s what might be happening, according to astrophysicists Ermanno Borra and Eric Trottier, from Laval University in Quebec; although they admit it’s only one possible explanation for what they appear to have discovered.
It was in 2012 that Borra predicted intelligent aliens might use the light from their own stars to signal their existence to the cosmos. Using data from the Sloan Digital Sky Survey, Borra and Trottier analysed the spectra of 2.5 million stars to see if this might be the case – and found 234 which seem to be broadcasting a signal of the kind predicted by Borra.
The “signals” are pulses in the stars’ light, separated by a constant time interval. What’s more, all 234 stars are predominantly in the F2 to K1 spectral range, which is the small range of stars centred on the spectrum of our own life-supporting Sun, and thus the broad group of stars thought might support life on planets orbiting them.
However, as Borra and Trottier note in their paper – which has yet to be comprehensively peer-reviewed – the pulses could be the result of natural factors such as rotational transitions in molecules or the Fourier transform of spectral lines. It might even be due to rapid pulsations in the stars themselves. Nevertheless Borra and Trottier have tended to dismiss rotational transitions on the grounds that such behaviour isn’t common to these types of star. They also think it unlikely a Fourier transform is responsible.
Instead, they lead towards either the “signals” being an artefact produced by data reduction on the part of the Sloan instrument, or the work of ET, with a slight emphasis towards the ET side of their thinking. Others, having read their paper, are far more sceptical.
“It seems unlikely that 234 separate alien societies would be sending out such similar signals more or less simultaneously” Seth Shostak, a senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California said. “It would be like expecting us to send the same signals as the Abyssinians — it doesn’t make a whole lot of sense.” Instead, Shostak leans towards the data reduction explanation; as does Occam’s Razor.
But a further possible explanation has been suggested: that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars which has never been previously encountered. While not as exotic as aliens using their stars as signalling devices, should this prove to be the case, it would still be a remarkable new discovery.
Is It an Alien Mega-structure or a Cloud of Comets?
Aliens fiddling with their stars to generate signals brings me to the mystery of Tabby’s Star – more formally known as KIC 8462852, an F-type main-sequence star located in the constellation Cygnus approximately 1,480 light years from Earth. It came to prominence in 2015 after data gathered by the Kepler exoplanet mission revealed it is experiencing massive and irregular dips in brightness of up to 22% at a time, which last for several days before the star reverts to its “normal” brightness once more.
Fluctuations in the brightness of some stars isn’t that unusual, and can be down to a number of reasons. Kepler, for example, looks for regular dips in a star’s brightness which might be the result of a planet moving between the star and itself. However, the sheer magnitude of the fluctuations experienced by Tabby’s Star are hugely beyond anything previously seen, making it the subject of intense study over the past year by professionals and amateurs alike.
Various theories have been put forward for its behaviour, Tabetha S. Boyajian, the lead researcher into the initial study of the star, and after whom it is informally named, believes an enormous cloud of comets orbiting the star is responsible. These comets, circling their parent star, are colliding, breaking up, forming small clouds sufficient in size and density to create a host of irregular and chaotic variations in Tabby’s light. Other’s aren’t convinced; while such clouds would block visible light from the star, they would themselves be sources of infra-red radiation, which hasn’t been detected.
Perhaps the most exotic theory for the fluctuations is that Tabby’s Star is the home of an alien civilisation so advanced it is constructing a Dyson Sphere around the star. This is a hypothetical construct that completely encompasses a star and captures most or all of its energy output, giving said aliens access to unlimited power. Those supporting this idea believe that the periodic dimming and brightening of the star is the result of enormous parts of this sphere periodically passing between the star and Earth.
As unlikely as such as idea sounds, it has led to a team of researchers listening to Tabby’s star in the hope of detecting communications passing back and forth between these extra-terrestrial engineers as they work on their gigantic enterprise. The researchers are doing so using the Green Bank Telescope in West Virginia, which has been hooked-up to a special SETI instrument that can listen to and record an enormous swath of bandwidth simultaneously in billions of different radio channels in the hope of detecting signals of artificial origin.
The first period of listening to Tabby’s Star took place over an 8-hour period on October 26th. Two more listening periods are scheduled for in November and December. After this, the gathered data will be analysed for any signs of possible artificial signals. Will they find anything? Members of the team themselves admit it’s a billion-to-one chance that they do; but it’s an intriguing experiment.
Juno Recovers from Safe Mode: Engine Issues Continue
“Juno exited safe mode as expected, is healthy and is responding to all our commands,” Rick Nybakken, Juno project manager from NASA’s Jet Propulsion Laboratory reported on Tuesday, October 25th. “We anticipate we will be turning on the instruments in early November to get ready for our December flyby.”
This is good news for the mission to probe Jupiter’s mystery after the safe mode became one of two mishaps to throw the mission slightly off-balance. A software anomaly prompted the vehicle to enter the protective mode, shutting down all but essential systems on October 19th, 2016, just hours before Juno was due to make its third close flyby over Jupiter’s cloud tops.
It had been intended that the flyby would be used to complete an engine burn to reduce Juno’s passage around Jupiter from a 53.5 day elliptical orbit to a more circular 14-day primary science orbit. However, the engine burn had been scrubbed on October 17th, when telemetry revealed an issue with a set of valves in the engine.
With Juno now fully recovered from the safe mode incident, it will be able to resume normal science operations. The issue with the engine valves, however, is proving more problematic. Immediately after it occurred, it had been hoped to simply postpone the engine burn until the next close flyby of Jupiter in December. Now the mission team are considering leaving Juno in its extended orbit until February 2017 as they continue to work on the problem.
All New Horizons Data Received
The final bits of data collected by NASA’s New Horizons spacecraft during its speedy flyby of Pluto in July 2015, were received on Earth on Thursday, October 27th, 2016, bringing to a close the downlink of over 50 gigabits of data from the probe, which has taken more than a year to complete.
The transfer has taken some long in part because it couldn’t be handled continuously. New Horizons has had to perform manoeuvres when have interrupted communications from time to time, whilst there were also times when the receiving dishes of NASA’s the Deep Space Network were engaged in other tasks, also interrupting the information flow.
However, it did not require all of the data to reach Earth in order for it to excite scientists. As I’ve reported in this column, much of the information received over the past 15 months has completed overturned many assumptions about dwarf planets in general and Pluto in particular, revealing it to be a surprisingly active little world.
“The Pluto system data that New Horizons collected has amazed us over and over again with the beauty and complexity of Pluto and its system of moons,” said Alan Stern, New Horizons principal investigator, as the final data was received. “There’s a great deal of work ahead for us to understand the 400-plus scientific observations that have been sent to Earth. And that’s exactly what we’re going to do—after all, who knows when the next data from a spacecraft visiting Pluto will be sent?”
Meanwhile, New Horizons remains on course for a January 1st, 2019, flyby of Kuiper Belt Object 2014 MU69, a frozen world just 21 to 40 km (13 to 25 mi) across, lurking a billion miles beyond Pluto.
Virgin Galactic to Resume SpaceShip Two Glide Flights
Virgin Galactic is planning to begin glide flight tests of its SpaceShipTwo spaceplane on Tuesday, November 1st, almost exactly two years after a fatal crash of its first suborbital vehicle intended for space tourism.
Virgin Galactic test pilot CJ Sturckow announced on October 29th that the first glide test will see VSS Unity resume the test programme initiated with the ill-fated VSS Enterprise after just a single captive / carry test flight in September. It is expected that the Unity will complete a shorter series of glide tests compared to Enterprise, as the two vehicles are aerodynamically similar, allowing engineers build on the data obtained from Enterprise. After this, there will be a move to a series of powered test flights using an improved rocket motor Virgin Galactic has been developing.
No firm date has been given on when Virgin Galactic expects to start operating the system on a commercial basis. However, in August 2016, the US Federal Aviation Administration (FAA) awarded the company their first operating license, allowing them to start passenger-carrying flights once all flight test requirements have been met.