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  • Three new instruments will build upon groundbreaking work by the Solar Dynamics Observatory, shown here. This gallery contains some highlights. NASA
  • A good-sized coronal hole at a slanted angle is nearly centered on the face of the sun in late 2018. Coronal holes are magnetically open areas from which solar wind particles speed into space. NASA/GSFC/Solar Dynamics Observatory
  • NASA's Solar Dynamics Observatory scientists use computer models to generate a view of the sun's magnetic field. Here is an extreme ultraviolet view of the Sun with the same image showing the superimposed field lines. The bright active region right at the central area of the sun clearly shows a concentration of field lines, as well as the small active region at the sun's right edge, but to a lesser extent. Magnetism drives the dynamic activity near the sun's surface.
  • On Nov. 7, 2018 for just under an hour, SDO viewed a lunar transit, when the Moon partially blocked SDO's view of the Sun. At its peak about 44% of the Sun was covered. NASA/GSFC/Solar Dynamics Observatory
  • The lone active region visible in April, 2018, on the sun put on a fine display with its tangled magnetic field lines swaying and twisting above it when viewed in a wavelength of extreme ultraviolet light. NASA/GSFC/Solar Dynamics Observatory
  • A good-sized active region with bright, towering arches began to rotate into view in April, 2018. NASA/GSFC/Solar Dynamics Observatory
  • For the first time in a long time the Sun has gone an entire month without any sunspots (Feb. 1-18, 2019). To put this in context, for five years (2011-2015) surrounding the latest solar maximum in March 2014 – the period when the Sun's magnetic activity is the most intense – there were only three days without any sunspots. NASA/GSFC/Solar Dynamics Observatory
  • Coronal holes appear dark in certain wavelengths of extreme ultraviolet light like the one here. They are areas of open magnetic fields from which solar wind rushes out into space. NASA/GSFC/Solar Dynamics Observatory
  • A small prominence hovered above the sun's surface over a two-day period in June, 2018, before breaking off into space. Prominences are cooler, darker clouds of plasma tethered above the sun by magnetic forces. These clouds of gases are notoriously unstable. NASA/GSFC/Solar Dynamics Observatory
  • NASA's Solar Dynamics Observatory ran together three sequences of the sun taken in three different extreme ultraviolet wavelengths in March, 2018. In the red sequence (304 Angstroms), we can see very small spicules and some small prominences at the sun's edge, which are not easy to see in the other two sequences. In the second clip (193 Angstroms), we can readily observe the large and dark coronal hole, though it is difficult to make out in the others. In the third clip (171 wavelengths), we can see strands of plasma waving above the surface, NASA/GSFC/Solar Dynamics Observatory

The Sun is our closest star, and without it life on our world could not survive. So it is essential to understand its nature. And yet, even though the Sun shines brightly on every clear day on Earth, it is difficult for astronomers to observe the star closely for a number of reasons.

Most obviously, it is hot—so hot, it is difficult to get too close without getting burnt to a crisp. Additionally, due to high solar gravity, it requires a lot of energy to insert a spacecraft into an orbit near the Sun. The harsh radiation near the Sun also plays havoc with the scientific instruments on spacecraft.

For all of these reasons, while astronomers have made steady progress in understanding the Sun and its effects on Earth, our atmosphere, and other bodies in the Solar System, we still have big questions. The good news is that we are now entering the golden age of Solar research with a major new ground-based telescope and two space-based observatories that will come close to the Sun.

"There is no doubt that the observations and insight will be unprecedented—exploring new regions with new instruments in incredible detail," David Alexander, a solar physicist at Rice University and director of its space institute, told Ars.

First light in Hawaii

You may have seen the amazing images recently released by the Daniel K. Inouye Solar Telescope, which is located on a mountaintop at 3,084 meters in Maui, Hawaii. With a 4-meter aperture, it is the world's largest solar telescope. The new images were part of the first test observations, with routine science observations set to begin this summer.

Images and video of the Sun from the telescope showcase features as small as 30km, the best resolution ever observed. Cell-like structures about the size of Texas—they also look like popcorn, or small nuggets of gold—boil across the Sun's surface, bringing heat from the interior of the star to the surface. This hot plasma then cools slightly and sinks back below the surface of the Sun. It is all rather mesmerizing.

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