Selecting only ten events from the past year is always a hard task – space science and exploration is just so exciting and fast-paced that there is always something going on, or something about to be revealed or discovered! In no particular order, here’s a summary of some of the exciting events from the last 12 months.
Occultations of Saturn by the Moon in NZ
The Moon with Saturn treated us to several celestial events this year. In the early hours of 26 April and the late evenings of 12 August and 2 November, Saturn was occulted (covered) by the Moon as seen from New Zealand. On these occasions Saturn was hidden by the Moon, giving stargazers impressive naked-eye views and even better telescopic and photographic opportunities just before and after the occultations occurred. There was also an ‘almost’ occultation on 16 July where Saturn came very close to the Moon (as seen from NZ). These celestial events are called conjunctions.
Viewing such events through a telescope heightens our awareness of the scale of the Solar System. While Saturn looks tiny against the looming bulk of the Moon we know that it’s much larger. It would take 33 moons to span the diameter of Saturn, however, Saturn is more than 3,500 times further away!
Stunning Mercury Transit
This rare astronomical phenomenon was briefly visible for early risers in New Zealand on 12 November as Mercury passed in front of the Sun. From Earth, stargazers can only ever see two planets transit our Sun – Mercury and Venus. The opportunity to watch a Mercury transit occurs around 13 times a century despite its orbit around the Sun being only 88 days. The reason we don’t see a transit four times a year, however, is because its orbit is tilted in comparison to Earth’s and usually passes just beneath or above the Sun, making it completely invisible to the naked eye. The next transit of Mercury will take place in November 2032 and will again only be briefly visible from New Zealand.
Beresheet lunar crash
With Israel’s Beresheet lander crashing into the Moon during descent in April of this year, it reminds us of the difficulties of space exploration. Beresheet, Hebrew for “in the beginning”, was a joint project between SpaceIL, a privately funded Israeli non-profit organisation, and Israel Aerospace Industries. After a seven-week journey, the robotic spacecraft approached a final orbit at 15km from the surface. The mission’s aim was to take pictures and conduct experiments. Beresheet attempted a soft touchdown but suffered technical problems on its descent.
Tensions were rising in the command centre as communications were lost before Opher Doron, the general manager of Israel Aerospace Industries’ space division, announced there had been a failure in the spacecraft.
The very first image of a black hole
Accomplishing what was previously thought to be impossible, the first image of a black hole is the astounding achievement of the EHT (Event Horizon Telescope project). A collaboration of over 200 scientists around the world using an array of observatories scattered all around the globe came together with the observatories acting like a giant telescope the size of Earth. This led to the accumulation of over a petabyte of data while staring at M87’s black hole. After two years, scientists were able to use this data to assemble the mugshot, revealed to the world in April 2019.
South American total solar eclipse
Gazers worldwide were left in awe on 2 July as the Moon blocked out the Sun over Chile and Argentina. It was a celestial event that gained a worldwide audience and was the first total solar eclipse since the ‘Great American Eclipse’ in 2017. The Moon’s shadow began to traverse the southern Pacific Ocean at roughly 2 PM EDT and was clearly spotted on weather satellite imagery. With Earth near aphelion and the Moon near perigee, the event was almost twice the duration of 2017’s. Totality lasted for slightly more than two minutes for those who were strategically placed on Tuesday afternoon.
The first place on the continent to see the total solar eclipse was La Serena, Chile, and the last place was just south of Buenos Aires, Argentina. Meanwhile, much of the balance of the continent witnessed a partial solar eclipse or tuned in to watch it on NASA TV.
New year’s fly-by
As the world celebrated the beginning of 2019, at 12:33 AM EST a small spacecraft named New Horizons made history as it flew by a small object nicknamed Ultima Thule. This mysterious object lives in the Kuiper Belt, a somewhat unexplored place due to the sheer distance and time needed for any spacecraft to reach it. This region of space lies beyond the orbit of Neptune and contains icy relics that are the leftovers of the Solar System’s formation, including dwarf planets, and comets. This cosmic rendezvous occurred so distantly that it took more than six hours for a signal from New Horizons to reach Earth.
At over 6.4 billion km away at the time of the fly-by, this encounter made Ultima Thule the most distant object ever explored by humans.
Saturn and its moons
The recent discovery of 20 new moons gave Saturn a Solar System record! Jupiter may hold the record as the Solar System’s king, but Saturn now holds the title of having the largest entourage. A team led by Scott S. Sheppard discovered 20 new moons, giving Saturn a total of 82 moons (overtaking Jupiter by three). Saturn’s newfound moons are all about five kilometres wide in diameter and are so faint that they are just about at the detection limit for the Subaru telescope in Hawaii.
Saturn and its rings
NASA’s Cassini spacecraft ended its historic exploration of Saturn in 2017 and scientists are still learning more about the ringed planet. Data from the 13-year mission helped scientists determine that Saturn’s rings are younger than previously thought as well as the fact that they’re also disappearing! NASA confirmed the rings were being pulled into the planet by gravity, and its magnetic field was pulling in a dusty rain of ice particles from the rings, also known as ’ring rain’. From this alone, the entire ring system will be gone in 300 million years.
India (almost) made it to the Moon
Millions around the world watched the Vikram Moon lander’s final heart-stopping descent on the dawn of 7 September. The spacecraft was launched from the second launch pad at the Satish Dhawan Space Centre on 22 July by a Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III). It reached the Moon’s orbit on 20 August and began orbital positioning manoeuvres for landing, scheduled to land on the near side of the Moon on 6 September to conduct scientific experiments for one lunar day. However, the lander deviated from its intended trajectory at 2.1 km altitude and lost communication when touchdown confirmation was expected. Initial reports suggesting a crash were confirmed by ISRO chairman K. Sivan, stating that “it must have been a hard landing”.
The Failure Analysis Committee gave a statement that the crash was caused due to a software malfunction that operated only one of its five main engines during the final landing phase. Looking forward, ISRO may re-attempt a soft landing by November 2020 with Chandrayaan-3.
SpaceX’s prototype rocket set a record and flew to its highest altitude yet during hover test. The next-generation rocket was launched for a second time in south Texas, reaching the height of a small skyscraper before it landed back on Earth. The flight established the vehicle’s ability to take off and land in a controlled manner and paves the way for more aggressive testing of the vehicle’s design in the months ahead. SpaceX’s first prototype for its Mars-colonising Starship vehicle reached a hover altitude and then flew sideways to touch down at a separate nearby landing pad. The entire flight lasted just 57 seconds.
Images: TOP – Occultation of Saturn & Mercury Transit. Credit: Josh Kirkley. MIDDLE: Dr Katie Bouman with the code used to image the black hole. Credit: Dr Katie Bouman. First ever image of a black hole. Credit: EHT. BOTTOM: Artist’s impression of Saturn and its moons & diagram showing the various orbits of the newly discovered moons. Credit: Credit: Carnegie Institution for Science.