Kaja Fenn

As the year 2016 has drawn to an end it is time for some kind of review or reflection. What a year it has been! One could argue that it has been a terrible year for politics and for science.It is easy to focus on bad and ugly, but I would like to think about something good and there have been some fantastic science stories this year. When it came down to it, I actually struggled to pick just three, so without further ado:

3. The Planet Nine

Artist impression of the view of the Sun from Planet Nine. Source: Nature

It’s not the first time that the idea of a ninth planet in our Solar System has been proposed. The presence of a ninth planet, back then “Planet X”, in the Kuiper Belt* has been suspected since the discovery of Neptune. Scientists have calculated there must be a larger planetary body that would explain the inconsistencies in the orbits of Uranus and Neptune. And so the hunt began for the planet began… Fast forward roughly 170 years through the discovery of Pluto, the demotion of Pluto, and the discovery of other trans-Neptunian dwarf planets such as Eris and none of which were able to explain well enough Uranus and Neptune orbits.

Potential orbit of the planet Nine. Source: K. Batygin and M. E. Brown, The Astronomical Journal, 151, 22 (2016)

In January 2016 researchers at the California Institute of Technology, discovered Planet Nine. Sadly, the planet has not been directly observed (yet!); rather it was ‘discovered’ through simulations and mathematical models. These models offer the best explanation so far as the probability of the other planets in our Solar System following their current paths and displaying a congruent orbital tilt without the existence of Planet Nine is “about 0.007 percent”. The planet is thought to have 10 times the mass of the Earth and orbits the sun every 10,000 to 20,000 years. This orbit could stretch from 200 to anywhere between 600 and 1200 AU’s  (an AU – astronomical units equates to 150,000,000km – roughly the distance between the Earth and the Sun). It is currently unknown whether this planet resembles the gas giants in our Solar System, or the ice-balls.

This is very exciting news as there have been only three planets discovered in our Solar System in the last two millennia!

*Kuiper Belt – a circumstellar ring extending from Neptune’s orbit and surrounding our Solar System made up from dwarf planets, moons, asteroids etc.

2. Rocket recycling

In 2016 we have taken another step closer to space travel. Space travel is very expensive and cutting the costs down are critical for it being available to the public. One area which attracted a lot of research interest is the launch. This is because the main booster is usually discarded into the ocean as soon as it finished powering the rocket or ship into space. Companies such as SpaceX and Blue Origin have been working on creating reusable rockets that are capable of returning to Earth. By the end of 2015, Blue Origin achieved just that, sending a rocket into sub-orbit and returning it to Earth. In 2016 Space X made history by finally sending a rocket into orbit and safely landing it: not just on the ground, but on a floating drone ship.

1. Gravitational waves

This will probably go down not only as the discovery of the year, but probably of the decade, if not the century. Gravitational waves were originally predicted by Einstein’s general theory of relativity at the beginning of the 20th century but their direct observation eluded astrophysicists. Until this year… In February 2016 scientists from Laser Interferometer Gravitational-Observatory (LIGO), reported a collision of two black holes, which are 29 and 36 times the mass of our Sun. Then in June 2016 detectors picked up waves sent by the collision of another two black holes 1.4 billion light-years from Earth.

Two black holes merging. Source: LIGO

Gravitational waves are ripples in space-time travelling at light speed. It’s a bit like the wobbling of a jelly propagating away from a spoon tap. The waves are incredibly weak, which is why they have been so hard to detect. However, the more energetic and violent the process at the source (such as black hole collisions, supernovae, coalescing neutron stars or white dwarf stars), the easier they are to pick up. Gravitational waves carry information about the event that has created them, therefore giving us new insights into the origin of the Universe, and also allowing us to investigate space in a completely new way (including objects and events that ordinary telescopes cannot detect). Scientists can use this to test where Einstein’s theory doesn’t quite fit.

A special mention to two NASA space missions for providing most fantastic images that have captivated imagination of millions of people this year. 1) Cassini’s mission is drawing to a close this year (September 2017) – so in the 2016 we have seen return of the photos of the Saturn’s ice moons and rings (follow @CassiniSaturn). 2) After 13 year journey – Juno (follow @NASAJuno) – has finally reached its destination, Jupiter. Over the next few years it will help to understand the story of the Giant Planet.

Sun highlights Saturn’s north pole with it’s strange hexagonal polar vortex.
Juno captures one of the rotating giant storms, white pearl, on Jupiter’s southern hemisphere. These storms have diameter approximately the size of the Earth.