The judges of the Astronomy Photographer of the Year 2015 had a difficult job. From over 2700 entries, they had to get a shortlist of 138, then choose 32 winners in nine categories and two special prizes. And finally, agree on an overall winner.

Total eclipse
The winning photograph depicts one of the most magnificent, awe-inspiring – yet eerily disturbing – phenomena that we can see in the sky: a total solar eclipse. In March 2015 an eclipse occurred in the far north, witnessed by no more than a few thousand people. (The 1999 eclipse was seen by up to 350 million people.)

Luc Jamet (France) was in Svalbard, an archipelago about halfway between northern Norway and the North Pole. In “Eclipse Totality over Sassendalen”, except for its bright corona, the Sun is hidden by the Moon. A desolate snowy landscape is dark beneath the eclipsed Sun. Yet in the sky you can see where the Moon's shadow ends. One judge described it as “otherworldly” and all the judges were in agreement that this was the winner.

Another image of this eclipse cane from an unusual source, both in terms of the photographer and the location. Highly Commended in the Young category, Philippe Rowland (UK), aged 7, took his picture with an iPad Mini on a charter flight over the Faroe Islands with his family. His image shows the Sun as a ring of light in a black sky.

Our Sun
Our Sun had both a high-tech Winner and and an unexpected low-tech Highly Commended.

With a telescope, special filter and lots of expertise, Paolo Porcellana (Italy) produced “Huge Prominence Lift-off”. He caught an big solar prominence beginning to detach from the Sun's surface. How big? About 700,000 km – you'd have to have 55 Earths in a row to match that distance.

“Solargraph” was quite a contrast. Chris Bakley (USA) used the technology of bygone days – a pinhole camera – to show the movement of the Sun through the sky over six months.

Solar phenomena in the sky
Aurorae, a new category this year, are the result of solar particles interacting with Earth's upper atmosphere. The winner was “Silk Skies” by Jamen Percy (Australia). I've seen many fabulous aurora photos, but nothing quite like this. Its composition is simple and unexpected, and the image surprisingly evocative.

Another splendid sky spectacle is noctilucent (night-shining) clouds. They're Earth’s highest clouds, forming in the mesosphere near the edge of space. It's only at high latitudes during the summer months that the Sun is at the right angle to illuminate them. Matt Robinson (UK) was the Runner-up in Skyscapes for “Sunderland Noctilucent Cloud Display”.

Deep space
The winning photographer in Planets, Comets & Asteroids, Lefteris Velissaratos (Greece), said of his photo, “That’s something you don't see more than once in a lifetime.” “The Arrow Missed the Heart” shows Comet/2014 E2 (Jacque) and the magnificent nebula NGC 896, whose common name is the Heart Nebula. The juxtaposition of these two contrasting objects is brilliant.

People & Space
The “Skyscapes” category needs an earthly landscape plus the sky, as in Luc Jamet's eclipse picture. However People & Space requires the inclusion of a human element. Interestingly, you can't actually see any people in the winning picture “Sunset Peak Star Trail”, taken by Chap Him Wong (Hong Kong). The people are there. They're climbing Sunset Peak under a starry night sky. But in this long exposure all we see of the people is the trails made by the lights they carry, and the stars are visible only as the trails created by Earth's rotation.

Young Astronomy Photographer
This category is for astronomers aged 15 or under – I've already mentioned Philippe Rowland, the youngest of the winners. But the Winner was George Martin (UK) for “A Celestial Visitor”. The visitor was Comet/2014 Q2 (Lovejoy). The photographer used some impressively sophisticated techniques to get the detail and structure of the comet without blurring it. We see star trails showing the movement of the comet against background stars.

Ethan Chappel (USA), was Runner-up for a detailed mosaic of the Moon for which he needed 16 frames. In addition, an excellent shot of Jupiter with three of the Galilean moons was Highly Commended.

And I'm also going to mention the Highly Commended “Cosmic Oasis” by Marcus Davies (Australia) in the Galaxies category. He photographed NGC 253, the Sculptor Galaxy, also known as the Silver Coin Galaxy. Besides its beauty as a starburst galaxy, it was discovered by my hero Caroline Herschel in 1783.

You can see all the winning photographs on the Royal Museums Greenwich website: https://www.rmg.co.uk/astronomy-photographer-year-competition/2015-winners