Earth’s largest and most powerful solar telescope has just given us breathtaking new images of the sun’s surface.
In a series of new images, the observations from the Daniel K. Inouye Solar Telescope reveal the intricate details of sunspot regions, the swirling convection cells and the motion of plasma in the solar atmosphere down to a resolution of about 20 kilometers (about 12 miles).
At this scale, the plasma textures resemble brushstrokes and textures resemble a painting. To put the distances into context, a single solar convection cell is on average slightly smaller than the US state of Texas.
However, these new Inouye images aren’t just designed to make you feel small and insignificant, they’re a preview of science to come as researchers analyze the solar surface in great detail to understand the processes that take place on it.
Sunspots are often larger than our entire planet and tend to be ephemeral spots where magnetic fields are unusually strong and appear darker than surrounding regions due to their relatively cooler temperatures. They’re also associated with our sun’s more violent outbursts: As magnetic field lines tangle, snap, and reconnect, they unleash incredible bursts of energy in the form of coronal mass ejections and solar flares.
Sunspot activity is not constant. It is linked to cycles of about 11 years in which sunspot and flare activity rises to a peak at solar maximum and falls to almost nothing during solar minimum. At solar maximum, the poles of the sun switch places; we are currently moving towards a solar maximum is expected to take place in 2025after which the solar activity will decrease again.
It is not known what drives these solar cycles, or causing sunspots. But this information is of great importance to us here on Earth, as the outbursts of the corona mass often associated with sunspots can emit huge clouds of charged particles that collide with the Earth’s magnetic field and risk creating a number of failures to our technologically dependent way of life.
The new Inouye images show several fine structures associated with sunspots.
For example, there is the umbra (the dark spots in the middle). Bright spots seen within the umbra are known as umbra dots. The penumbra is the brighter area around the umbra. This is characterized by clear strands known as penumbral filaments.
Occasionally a sunspot-like region of concentrated magnetic field can be seen that has an umbra but no peripheral penumbra. These are known as solar pores; they form when the conditions for the formation of a penumbra are not met.
And as a sunspot begins to recede and disappear, it can be crossed by bridges of light. Further decay causes the sunspot to lose its penumbra; it is very rare to record the process of this loss.
When the sun is still, it can look quite featureless in images captured in the visible part of the spectrum.
But even a quiet sun has a lot to do. Convection cells, as seen below, give the solar surface, or photosphere, its “popcorn” texture. Hot plasma rises from the center of the cell, then moves to the edges and falls back down as it cools. These convective cells, or grains, are astonishingly large, up to 1,600 kilometers (994 miles) across.
Above the photosphere is the solar atmosphere or chromosphere. It is sometimes populated by fine, dark, brushstroke-like plasma threads known as fibrils or spicules. They look like hairs, but the diameter of the fibril is in between 200 and 450 kilometers (125 to 280 miles). They burst from the photosphere and last a few minutes. Scientists don’t know how the fibrils are generated, but there are certainly many of them, and they are quite reliable indicators of the directions of the messy magnetic field of the sun.
Data from Inouye, scientists hope, will help unravel some of the lingering mysteries of these fascinating solar phenomena. That in turn could aid in understanding larger phenomena; the sun’s internal dynamics, for example, and what drives solar cycles.
The telescope is already delivering results. Earlier this year, scientists described the first-ever sightings of atmospheric solar waves in a sunspot.
“There is no other facility like the Inouye Solar Telescope,” said astronomer Thomas Rimmele, director of the Inouye Solar Telescope, said last year. “It is now the cornerstone of our mission to advance our knowledge of the sun by bringing industry-leading observing capabilities to the research community. It’s a game changer.”
You can view and download full resolution versions of the new images on the National Science Foundation website.