The astronomers at the Daniel K. Inouye Solar Telescope have just released a stunning image of a solar spot taken in January. The exquisite detail in it truly shows what this observatory, the largest solar telescope in the world, will be able to achieve once completed next year.

The full image is about 16,000 kilometers (10,000 miles) across, and would comfortably fit Earth inside. Sunspots are regions on the surface of the Sun that appear dark because they are colder than the surrounding areas. They are still extremely hot, though. Between 2,700–4,200°C (4,900–7,600°F) against the 5,500°C (9,900°F) of the solar surface.

The team has published an overview of the whole observatory in Solar Physics, starting with this stunning image of the Sun taken on January 28, 2020, and more detailed papers about the instruments' capabilities are due to be published in the next few months. 

“The sunspot image achieves a spatial resolution about 2.5 times higher than ever previously achieved, showing magnetic structures as small as 20 kilometers on the surface of the Sun,” overview lead author Dr Thomas Rimmele said in a statement.

The observatory, located on the island of Maui in Hawai?i, already stretched its muscles earlier this year with the most detailed view of the Sun ever taken. The delays in completion are mostly due to the pandemic and subsequent lockdown, which are necessary to keep everyone safe. Operations will start soon though, just in time to catch the beginning of Solar Cycle 25 and the increase of activity that our star will experience over the next few years.  

The choice of the sunspot is also symbolic. More spots form during the active period of the Sun’s 11-year cycle. So these kinds of views will become common as we approach the expected solar maximum in 2025.

“With this solar cycle just beginning, we also enter the era of the Inouye Solar Telescope,” added Dr Matt Mountain, president of the Association of Universities for Research in Astronomy (AURA), the organization that manages the Inouye Solar Telescope. “We can now point the world’s most advanced solar telescope at the Sun to capture and share incredibly detailed images and add to our scientific insights about the Sun’s activity.”

Together with the several space-based solar observatories, other solar telescopes on Earth, and spacecraft such as the Parker Solar Probe and Solar Orbiter, the Inouye Solar Telescope will be vital in providing an expanded understanding of the Sun.