The world's most powerful solar telescope has captured an incredible image of the Sun, following the switching-on of its brand new instrument.
It shows a cluster of sunspots on the surface of the Sun, the features often a sign that powerful solar flares and coronal mass ejections are on the way.
In the image, each pixel corresponds to 10 km (or 6.2 miles) on the Sun.
The telescope is the Daniel K. Inouye Solar Telescope, whose Visible Tunable Filter has just achieved 'first light', a term in astronomy used to mean the first time an instrument is pointed at and observes an object.
Testing the Visible Tunable Filter
The Visible Tunable Filter (VTF) is designed and built by the Institut für Sonnenphysik (KIS) in Freiburg, Germany, and is the world’s largest imaging spectro-polarimeter.
It captures images of the Sun at different wavelengths, giving solar scientists the opportunity to observe a variety of features and processes on the Sun.
Different wavelengths of light appear as different colours, and the VTF uses an alignment of glass plates – known as an 'etalon' – to enable solar scientists to filter through all the different colours.
The VTF's three cameras take several hundred images in a few seconds, then combine these images to build a 3D view of structures on the Sun.
Scientists at the NSF National Solar Observatory (NSO), which operates the Daniel K. Inouye Solar Telescope, have been calibrating and aligning the instrument since it was installed.
This image marks the culmination of that process, and the first of the instrument’s on-Sun observations. Full science operations are expected to begin in 2026.
"These successful first light observations underscore the unique quality and functionality of the instrument, setting the stage for exciting findings in solar physics in the coming decades," a statement from the NSO says.
"After all these years of work, VTF is a great success for me," says Dr. Thomas Kentischer, KIS Co-Principal Investigator and key architect behind the instrument’s optical design.
"I hope this instrument will become a powerful tool for scientists to answer outstanding questions on solar physics."
"The significance of the technological achievement is such that one could easily argue the VTF is the Inouye Solar Telescope’s heart, and it is finally beating at its forever place," says Dr. Matthias Schubert, KIS VTF Project Scientist.
Study the Sun, protect our planet
Beyond bathing Earth in light and warmth, and allowing for the emergence of the multitude species of flora and fauna that we see today, the Sun has a powerful effect on our planet in numerous ways.
Powerful solar winds hit our planet's atmosphere and cause the aurora.
Solar flares and coronal mass ejections can reach Earth and affect our communications networks. These can sometimes culminate in huge solar storms called 'Carrington events'.
The effect of the Sun across the Solar System is known as 'space weather', and understanding more about space weather enables scientists to understand more about the workings of stars in general, but also about predicting and managing of solar storms that can affect our daily lives down here on Earth.
"When powerful solar storms hit Earth, they impact critical infrastructure across the globe and in space. High-resolution observations of the Sun are necessary to improve predictions of such damaging storms," says Carrie Black, NSF program director for the NSF National Solar Observatory.
"The NSF Inouye Solar Telescope puts the U.S. at the forefront of worldwide efforts to produce high-resolution solar observations and the Visible Tunable Filter will complete its initial arsenal of scientific instruments."
"The Inouye Solar Telescope was designed to study the underlying physics of the Sun as the driver of space weather. In pursuing this goal, the Inouye is an ideal platform for an unprecedented and pioneering instrument like the VTF," says Christoph Keller, NSO Director.
