NASA image reveals hidden sunlight that may help solve solar mystery

As a new series of NASA observations show, there's a lot more to sunlight than meets the eye.

New observations by NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) revealed patterns of high-energy light from the Sun that are not visible to the human eye.

This hidden light could help solve a mystery related to our host star's incredibly hot outer atmosphere, the corona.

Imaging the extreme heat of the Sun's corona

The human eye is only capable of seeing a relatively narrow band of the electromagnetic spectrum, which constitutes a vast amount of different wavelengths, including visible light, radio waves, microwaves, and infrared light.

It's due to this phenomenon, for example, that NASA's James Webb Space Telescope is able to observe infrared light peering through massive cosmic dust clouds that we could not otherwise see through.

Now, NASA's NuStar telescope array has used its special imaging capabilities to pick up high-energy X-ray readings from the Sun that may shed new light on the solar corona. A new NuStar image released by NASA earlier this month shows high-energy X-ray radiation in the form of bright blue spots.

For the new image, the NuStar data is combined with observations of low-energy X-rays (the green light in the image) taken by Japan's Hinode spacecraft, as well as ultraviolet observations (in red) taken by NASA's Solar Dynamics Observatory (SDO).

New NuStar data could help solve a solar mystery

The blue spots are particularly important as they show the hottest areas of the Sun's surface. Scientists have long sought to solve the mystery of why the Sun's corona, or outer atmosphere, is so much hotter than its surface. Now, the new observations may help to provide new clues in the form of these superhot regions of the Sun, represented by the color blue.

The Sun's corona can reach temperatures of up to 3.6 million degrees Fahrenheit (two million degrees Celsius), while the photosphere below can be about 500 times colder. According to a blog post from NASA, "this has puzzled scientists because the Sun's heat originates in its core and travels outward. It's as if the air around a fire were 100 times hotter than the flames."

One potential solution to the mystery comes in the form of nanoflares, which are small bursts of heat and light in the Sun's atmosphere. These are smaller solar flares, but, much like solar flares, they produce material that is hotter than the average temperature of the corona.

The new NuStar data could help to catalog these small nanoflares and help scientists discern whether they are responsible for the mysterious excess heat in the Sun's atmosphere. They will also compare the data to images captured by NASA's Parker Solar Probe to attempt to gain a better understanding of the complex mechanisms of the solar corona.