Evrim Yazgin
Cosmos science journalist
This rather unique picture of our Sun won Australian astrophotographer Peter Ward second place in Royal Museums Greenwich’s global 2024 Astronomy Photographer of the Year awards in the category “Our Sun”.
The image is not only a picture of our Sun – it’s two pictures of the Sun in one. And there’s a little bit of the Moon in there too.
So what’s going on? We’ll let the image’s creator explain.
“It shows the difference between the solar corona between its maximum and minimum,” Ward tells Cosmos.
A rectangular ball
You’re probably used to seeing the Sun as roughly spherical – it’s a ball of gas, after all. Ward came up with a clever way of explaining the Sun’s cycle visually by translating its round shape into a rectangle.
Take a rubber band, for example. It is roughly circular. But if you take any point along its circumference and cut the band, what you end up with is a piece of rubber with two ends. Unfurling the band gives you a straight line.
Ward refers to this as a change from polar (circular) to rectangular, which is exactly what he did with this photograph of the Sun.
Ward’s image shows the level of activity in the Sun’s corona – the outermost layer of its atmosphere – at different stages of the solar cycle which lasts 11 years.
The lower half of the image shows the corona in 2017 during a solar minimum. The upper half was taken in 2023 during solar maximum.
“During solar minimum, the solar corona has just got a very sort of gentle, wave-like structure to it,” Ward says. “But as we get closer to the maximum, it starts to look a bit like a sunflower – lots of activity, lots of spikes, and the tendons tend to be quite spiky and interactive.”
“I tried many ways to compare the two,” he says.
“Often you just see two images side by side. But I thought there might be a better way to do this. I tried different colourisations and overlays and contrasts and everything, and it just wasn’t working for me. I thought, what if I just change it from what they call a polar image to a rectangular image and just put them on top of each other? That’s how the image was created.”
Under the shadow of the Moon
Usually, the solar corona is only visible from Earth during eclipses, Ward explains. “Otherwise, the photosphere [surface] of the Sun is way too bright.”
The corona extends millions of kilometres into space. The Parker Solar Probe was the first spacecraft to “touch” the Sun’s outer atmosphere at a distance of more than 13 million km from the Sun’s surface. The Sun itself has a diameter of about 1.4 million km.
Ward travelled to Jackson Hole in Wyoming, US to capture the image of the corona at solar minimum in 2017. His 2023 solar maximum image was captured in Western Australia.
“The corona is much dimmer than the Sun. The brightness is similar to a full moon in terms of what you can see with the naked eye. You need the brightness of the Sun to be blocked out by the Moon. What you’re left with is a shimmering, blue-white light that goes into space,” Ward explains. “It’s really quite impressive.”
“I am a retired Qantas pilot. We did a charter over Antarctica – I think it was 2003 – for Croydon travel,” Ward recounts. “We had one to cabin crew up on the flight deck as we flew into an eclipse. She’d never seen one before. When it was all done and dusted, she was crying. I asked if she was okay and she said, ‘I just found the whole thing incredibly amazing and so moving. I had no idea that nature could put on such a show.’”
The thin, black line running across the middle of Ward’s image is the outline of the Moon as it passes over the Sun.
Reddish-pink arches near this line – more abundant in the solar maximum top-half – are bits of the solar atmosphere’s middle layer, the chromosphere.
Joys of astrophotography
“Solar imaging, to me, is a bit of a joy in that it doesn’t take very long,” Ward says. “I just go out to my backyard observatory, uncover the scopes, and I’m done and dusted in about 10 minutes flat.”
“To do deep sky, the light’s a lot dimmer, so you’ve got to take a lot longer exposure The other issue with deep sky photography is the weather and neighbours, lights and cloud,” he notes. “It would be nice to have a remote mountaintop observatory somewhere, but I’m stuck on the southern outskirts of Sydney.”
Ward used his own equipment to take his corona images. And he says astrophotography is becoming more accessible to amateurs.
“It’s never been easy as it is now,” he says. “I started in the realm of film, where we used to bake our canisters of 35-millimetre film in a tank. You develop it yourself in a dark room. The annoying thing was that everything you did up to taking the exposure you thought you got right. But quite often, when you actually develop the film, you find either you’d bumped the telescope, or everything was bit out of focus. All this takes time just to realise you made a mistake.
“Whereas in the realm of imaging with digital cameras, you basically get a read out instantly and you can just tweak the focus and tracking and everything else. And digital cameras now are really very capable and very affordable.”
Ward encourages other amateur astrophotographers to take their interest seriously.
“I went to the University of Western Australia and started doing a physics degree with a mind to perhaps be an astronomer. When I finished, two things put paid to that: I wasn’t getting straight As and Bs and there were no jobs at the end of it all.
“I finished off the degree but never actually used my academic qualifications. But I always kept the interest in astronomy. One of my old physics lecturers found out I had a little telescope and took me under his wing. He told me how the sky was mapped, how it worked and how to find stuff.”
Ward’s award
Ward says getting second place in the Astronomy Photographer of the Year awards “is just staggering.”
“Royal Greenwich is like the Olympics for astrophotographers,” he says. “There are thousands of entrants from 60 different countries. To go toe-to-toe with these people and actually be on the podium is quite humbling.”
“I would like to have come first!” he laughs. In fact, Ward did come first in the “Stars and Nebulae” category in 2020.
“One thing about Greenwich is it’s a very innovative competition,” Ward comments. “You’ve got to bring something new to the table. It’s always a challenge to come up with something different every year.”
“And there are guys that have got mountaintop gear that they put on the Chilean high desert and they’re all remotely controlled. It’s very hard to compete in terms of depth of image and clarity. So, I’ve tried to concentrate on southern hemisphere objects, but display them in a way which isn’t the ordinary.”
Ward says he’s working on imaging the Large Magellanic Cloud at the moment.
“I’m not sure what I’m going to pick in there, but there’s a thing called the Tarantula Nebula which hasn’t really been treated that well by amateurs over the years.”
Not just pretty pictures
Astrophotography often produces stunning images. But these pictures can sometimes have scientific merit because of their composition or their subject matter.
Ward says amateur astrophotography can lead to “It’s visualisation tools and other things.”
He mentions that he has already been contacted by university physics teachers who want to display his image in texts to help explain the difference between solar minimum and maximum to students.
Ward also notes that some amateur astrophotographers in the US and Europe who collaborate with astronomers to do deep exposures of the sky.
“They have actually revealed undocumented objects as a result.”
Astrophotography images, Ward says, “have been used by both professional and amateur ranks.”
“But amateurs have the luxury of time, whereas a lot of professional observatories are given scheduled observing on the big telescope. They’re lucky if they get half an hour.
“An amateur may not have such a big telescope, but I can bang away at something for 100 hours and get deeper images than they do. It gives you that luxury of prodding around at something that might be interesting or might not. On the odd occasion, people have discovered something new, and it’s been picked up and papers been written about it.”
