The Sun has fascinated scientists, inspired musicians, poets and artists, in all societies right across the world. As it tours, Helios will allow us to observe and contemplate cultural similarities and differences around the world. Depending on where the artwork is presented, its meaning and interpretation will shift.
Solar Science
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is by far the most important source of energy for life on Earth. The Sun releases energy in many ways: the usual flow of light that illuminates the Earth and makes life possible but also, in more violent and dramatic ways. It gives off bursts of light, particles, and magnetic fields all the way out to the Solar System’s magnetic edge. Scientists study the Sun to better understand how it and other stars in general work and also how its ever-changing conditions can influence Earth, other planets and comets in the Solar System. Find out about NASA’s Parker Solar Probe, which is flying close to the Sun to discover its secrets.
Imagery for Helios
The imagery for the artwork has been compiled using photographs of the Sun provided by Astrophotographer Dr Stuart Green (taken between May 2018 to June 2024) and NASA observations of the Sun, with guidance from solar scientist, Professor Lucie Green of University College London (UCL). The sculpture also features the source of the solar flares which caused the Northern lights to be visible from the UK in May 2024.
The Sun can be photographed with specially adapted telescopes revealing different aspects of its composition. The imagery being used to develop the Helios artwork was made using Hydrogen Alpha imagery, accurately revealing the surface of the Sun (chromosphere). The temperature of the chromosphere is about 6000 to 50000 degrees Celsius. The Sun rotates on average once every 27 days, interestingly, the equator rotates more quickly than the poles.
Over 400,000 photos of the Sun were used to construct Helios. The solar sphere is a composite of multiple high-resolution images of the Sun’s chromosphere using a 150 mm refractor operating at f34 fitted with two narrowband hydrogen alpha filters (passing only red light at specifically 656.28 nm) and a Basler acA1920-155 um monochrome camera. For each image, the process involved recording on a computer between 3000-7000 individual frames and subsequently processing by stacking, deconvoluting and sharpening to create the individual photographs which were then coloured and used to create the globe.
Scale of the Sun and Helios
The artwork measures 7 metres in diameter, so compared to the size of the Sun (1.39 million km) the artwork is at an approximate scale of 1:200 million. Each centimetre of the artwork’s internally lit spherical sculpture represents 2000km of the Sun’s surface. The Sun’s diameter is 109 times that of Earth – about 1,391,400 km (864,600 mi). So compared to the Sun sculpture, the Earth would be about the size of a tennis ball and on average 750m away.
It takes light from the Sun 8 minutes to arrive to us on Earth. Find out more about the science of the Sun.
Northern Lights – Aurora Borealis
At any given moment, the Sun is ejecting charged particles from its corona, or upper atmosphere, creating the solar wind. These Coronal Mass Ejections (CME) are large expulsions of plasma from the Sun which travel out into space. This solar wind slams into Earth’s ionosphere, or upper atmosphere, the aurora is born. In the Northern Hemisphere, the phenomenon is called the northern lights (aurora borealis), while in the Southern Hemisphere, it’s called the southern lights (aurora australis).
The particles are deflected towards the poles of Earth by our planet’s magnetic field and interact with our atmosphere, depositing energy and causing the atmosphere to fluoresce.
Helios music composition by Duncan Speakman and Sarah Anderson
The soundtrack features the sounds of fire and heat; NASA space recordings from their sun missions; the dawn chorus; a beach in the height of summer; sun and light related religious festivals and uplifting ambient music to communicate the importance of the Sun for our collective mental health and wellbeing.
About the music Duncan Speakman said:
“It’s quite a challenge to try and capture the scale and power of the sun through a piece of music. For Helios, we took many different approaches and collated them into one long composition. The piece moves through a series of different expressions of the sun itself as well as its relationship with us and our planet, shifting back and forth from a human perspective to a planetary one. It begins with a gradual layering of multiple birds in a dawn chorus, before shifting into more expansive glowing choral works rising like the sun. We then tried to capture the celebratory aspects of the sun in different cultures and religions, juxtaposed with the harsh heat of desert plains. In the central section we combined multiple manipulated recordings of fire and solar flares from NASA with processed acoustic instruments to evoke the awe inspiring intensity of this burning plasma globe. The piece then leads its way into a violin sonata that hints at Western classical traditions of representing the seasons through music (along with a subtle reference to a certain Beatles song). The final section of the piece draws on NASA mission recordings and seaside atmospheres before drifting into warm vistas of blurred instruments and vocals, hazy mirages fading into soft light.”
Artists inspired by the Sun
From ancient depictions of the Sun as a God or deity, through to Impressionist painters in western culture trying to capture the effect of the Sun’s light in the landscape, artists have always been enthralled by the beauty, power, majesty that the Sun brings.
In more recent times artists have sought to examine the Sun in new ways. Notable contemporary artists include: Olafur Eliason, James Turrell, Nancy Holt, Markus Kayser, Rafael Lozano-Hemmer, Roger Ackling