The year is almost over, so let’s look back at the exciting astronomy and space science developments of 2015.

10: Hubble turns 25

This year Hubble Telescope celebrated 25 years of delivering the most epic space images.

The impact of a quarter-century of images from Hubble is immeasurable. However, the mission didn’t go entirely to plan. At the beginning, the images from Hubble were blurred and out of focus. The main mirror had a major manufacturing flaw… an error that was only 1/50th the thickness of a sheet of paper. A mission to correct the optics was launched later. Seven astronauts conducted the first servicing mission and installed two new cameras. We received the first clear photos from Hubble in January 1994, and we never looked at space the same way again.

Hubble is due to retire and will be replaced with the James Webb Telescope, which will be launched in 2018. However,  NASA has stated that Hubble will continue to transmit for as long as it is functioning.

9: 50th anniversary of the first spacewalk.

Another notable event this year was the 50th anniversary of the very first spacewalk. On 18 March 1965, Alexey Leonov stepped outside the Voskhod-2 and into space (and space history) as the first person to complete a spacewalk. His walk took 12 minutes and 9 seconds, but nearly ended in disaster when Leonov’s suit distorted and inflated and he wasn’t able to re-enter the airlock. Find out more here.

8: Lunar eclipse treat

We were treated to two lunar eclipses in 2014, and one visible lunar eclipse in April 2015 as part of the 2014-2015 tetrad. The clouds parted here in Auckland, and we saw the eclipse clearly. It’s an impressive sight and deserves a spot on the top 10 list.

7: Launching and landing a rocket

Space agencies have been launching rockets for decades but landing a rocket to be reused again has evaded the most advanced scientific and engineering teams… until recently. Commercial rocket companies have taken on this challenge and in April Space X attempted landing its Falcon 9 rocket – and it got so close! Unfortunately, the vessel crash-landed in spectacular fashion. However, just this month the Blue Origin team safely landed their suborbital rocket, New Shepard. Although there are many differences between the two rockets, it’s exciting to watch this previously, expensive, “disposable” object turn into a reusable resource.

6: Philae lander sends back data

The Philae lander landed on Comet 67P in November 2014 – a monumental achievement. What’s exciting is all the data and discoveries that have come out of this mission. We’ve learnt that the comet has a diverse surface, made up of 16 different organic compounds. It also has a granular soil and was likely two smaller comets that joined in a relatively “slow” collision. Comets were once considered a possible source of the origin of water on Earth but data from Comet 67P have all but ruled that out. The molecular structure of the water detected on the comet is very different to that in Earth’s oceans.

As the comet approached its nearest point to the Sun, Philae warmed enough in June to ‘wake up’ and send recorded data. However, the last communication was on 9 July and no more is expected as the comet leaves the warmth of the Sun.

The Rosetta “mother craft” will continue orbiting Comet 67P and sending back images and data until it is slowly crash-landed on the surface in September 2016.

5: Boom! Clap! Surprise meteor lights up our skies

Early in the year we were treated to a large meteor burning bright across our night sky. It was seen across the country and was caught on dashcam. It’s a rare occasion to spot these astronomical events, so the fact it was caught on camera is a real delight. You can watch the clips here and here.

4: Dawn at Ceres

Since March, the NASA Dawn spacecraft has been orbiting the dwarf planet Ceres. Dawn had already orbited the giant protoplanet Vesta in 2011-2012 before arriving at Ceres. The mission objective is to investigate Ceres and Vesta, two objects in the main asteroid belt, and the evolutionary differences between them.

The Ceres mission has also provided amazing images, including shots of bright white spots on the dwarf planet. There are a couple of theories around the cause of the spots, one being a kind of salt, the other being ammonia-rich clays.

The Ceres team recently released a colourful map of Ceres highlighting the compositional differences present on the surface. “Ceres continues to amaze, yet puzzle us, as we examine our multitude of images, spectra and now energetic particle bursts,” said Chris Russell, Dawn principal investigator at the University of California, Los Angeles.

3: Rocket blows up

Grocery delivery gone wrong! The Orbital Sciences rocket, set to deliver supplies to the ISS exploded seconds after lift-off on October 28. The rocket held over 2,000 kilograms of food, scientific instruments and other supplies for the ISS crew. The flight was to be the third cargo mission for Orbital Sciences, part of a $1.9 billion contract with NASA. Investigations into the cause of the explosion have traced back to the AJ26 first-stage engines and moves have been made to discontinue using them. Thankfully, no one was harmed in the explosion, which you can watch here.

2: Liquid water detected on Mars

Mars continues to be a planet of fascination and the NASA announcement of liquid water found on Mars was a cause of much excitement. The liquid was more in the form of “seepage” and was found using an imaging spectrometer on the Mars Reconnaissance Orbiter (MRO). Researchers detected “signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet”. The dark streaks change over time, getting darker and seeming to flow down the slopes during Mars’ warm season, and fading in the cold seasons. You can read the full rundown of the discovery here.

1: We meet Pluto

The big news of this year was seeing Pluto for the first time in beautiful detail. At 7.5 billion kilometres away from Earth the New Horizons spacecraft had a long way to travel, in fact, it took ten years to travel to Pluto, with the help of a gravity assist from Jupiter. In the lead up to closest approach we received images of the planet, each one clearer than the previous, until July when we viewed a beautiful, high-resolution image of Pluto. The new view showed depth and dimension, and a now infamous “heart” shaped region – an 852kilometer-wide icy crater thought to be caused by a collision.

This mission has introduced us to a whole new world at Pluto, of icy-plains and mountain ranges, multiple soil types and textures, and most notably, one of Pluto’s moons, Charon. We’ve narrowed in on the sizes of Pluto and its moons, learnt that Pluto has a plasma tail and that its atmosphere is blown into space by solar winds, and we now know that Pluto is red, and complex hydrocarbon compounds cause this colouration.

It’s not just the planet that is impressive. The New Horizons spacecraft is the fastest spacecraft ever launched clearing Earth at 58,500 km/h and it’s the first ever probe to visit Pluto.

New Horizons is now travelling out into the Kuiper Belt region but it’s still hard at work transmitting data back to the NASA team, in what is called “departure science”. It will now visit another Kuiper belt object named ‘2014 MU69’. New Horizons has already changed what we know about Pluto, what it reveals about the Kuiper Belt and other distant objects…. We’ll just have to wait and see.