Many people have remarked on the two beautiful pictures of
the Aurora Borealis or Northern Lights which feature in our current Astronomy Photographer of the Year exhibition. Anyone who's been lucky
enough to see the aurora for themselves will know what a beautiful spectacle it
can be, so it's not surprising that we had quite a few photos of it entered
into this year's competition (which made the judging very tricky).

Earth's aurorae are ultimately caused by the Solar Wind, the stream of
energetic particles emitted by the Sun. Funnelled down towards the North and
South Poles by the our planet's magnetic field, these particles strike
molecules of air high up in the atmosphere, causing them to glow and
produce a shimmering display of lights. Because of this, aurorae are most
commonly observed at high northern and southern latitudes and indeed both of the
award-winning aurora photos this year were taken close to the Arctic Circle:
one from Canada and one from Norway.

At the Astronomy Photographer awards ceremony on September 9th I
found myself chatting to photographer Max Alexander who mentioned that some years ago he'd taken a
picture of an unusual aurora while working in Sweden.
I was very curious to see his photo and Max has kindly agreed to let
us post it here on the ROG blog. 

Max Alexander aurora

Max says: 

"I took this photograph of the Northern Lights while on assignment for
a book publisher to photograph the Ice Hotel, in Kiruna, Northern
Sweden, a perfect latitude from which to view them. 

"After several unsuccessful nights looking up, I met a couple who
invited me to their wedding ceremony in the adjacent Ice Chapel, and subsequent
reception. Every so often, I looked out of the window to see if the Northern
Lights would appear - and then they did, in all their breathtaking glory. I
convinced the wedding party to go out into the freezing arctic air, and they
were not disappointed. For twenty minutes there were audible gasps, as the
aurora borealis first snaked slowly, then rapidly danced across the sky in
giant and dazzling green arcs. I set my camera up quickly on my tripod, opened
up the aperture fully on a wide-angle lens, and then made a series of 15 second
exposures. Technically not difficult, I just needed to nail the composition.

"Back in London,
The Independent used one of those photographs on the cover of their magazine,
for a piece about Norwegian scientist Kristian Birkeland, the first person
to provide a scientific explanation of aurorae. I also contacted the University ofLondon
Observatory about
what caused this phenomenon and from that conversation I ended up doing a
diploma in astronomy at UCL, which in turn led me to take a series of
photographs on astronomy in the UK,
entitled Explorers of the Universe.

"I have reliably been told that this is a very rare photograph of the
intertwining twister effect that you can see and Patrick Moore is the only
person I have asked who has seen it in a photograph before. Mike Lockwood, a solar-terrestrial
scientist at theUniversity of Southampton, explained to me
that the aurora usually occurs in extended, curtain-like sheets. However,
sometimes, as here, it is restricted to a small rope-like form. The currents
flowing down the centre of such "auroral filaments" cause the
surrounding magnetic field to twist up into the helical forms that can be seen
here. The direction of the twist in this image shows that the dominant current
was upward.  In other cases the current can be downward and the twist
would then be in the opposite direction.

"By the way, the couple who got married have since become good friends of
mine, and the pictures of the Northern Lights are part of their wedding
photographs."

As the Sun continues to move into a more active phase of its eleven-year
cycle we can expect to see more auroral displays as increased solar activity
launches storms of particles in our direction. The Royal Observatory has a long
history of observing activity on the Sun and our Solar Stormwatch citizen science project allows members
of the public to help continue that research in the 21st Century (and also links to a great gallery of aurora images).

PIA13402-640

Finally, it's worth pointing out that the Northern
and Southern Lights are not just an Earthly phenomenon, as these spectacular
new images and movies of aurorae flickering around the poles of Saturn show. The
data come from NASA's Cassini spacecraft and we're
very pleased that Tom Stallard and his
team at the University of Leicester have allowed us to incorporate some of the
images into the Saturn option of our Solar System planetarium show Meet the Neighbours. So if you'd like to see
the Saturnian aurora in all its glory up on the dome come along to the show and
vote for Saturn as your destination.