Mysteries about the sun that still baffle science

A celestial first

In June 2025, the European sun-chasing spacecraft Solar Orbiter snapped the closest images of the sun ever taken, revealing the finest details of our home star's outer atmosphere, the corona. 

A better understanding of solar weather

The images are helping scientists understand more about the mechanisms that produce space weather, for example the presence of electromagnetic radiation and charged particles emitted by the sun, and the effects of solar wind—phenomena that can impact satellites, power grids, and communication systems.

Solar core temperature

The sun's core temperature reaches an average 15 million °C, or around 27 million °F. That's hot enough to sustain nuclear fusion!

The 'cool' surface of the sun

Conversely, the part of the sun we call its surface—the photosphere—is a relatively cool 5,500 °C (10,000 °F). But this is where it gets puzzling.

Rising temperatures

In fact, it reaches temperatures close to two million °C (3.5 million °F)—far, far hotter than the photosphere.

Solar wind

Scientists have long mused on why the sun's solar wind accelerates to such high speeds as it zooms away from our star's surface.

Solar energy

One explanation for this immense velocity is the fact that when larger than normal amounts of solar energy are released from the sun, the speed of the solar wind increases. However, this process is not yet fully understood.

Charging ahead

One theory suggests they take place when stored magnetic energy in the sun's atmosphere accelerates charged particles in the surrounding plasma.

Guessing game

The forecasting of flares and CMEs remains probabilistic and reactive. Scientists can determine when they have a high likelihood of occurring, but not specifically when one will erupt.

Sunspots

Sunspots, those circular dark-colored blemishes seen on the sun's surface, have long intrigued stargazers. They are a temporary phenomenon and, while studied in detail, the exact mechanisms behind the formation and behavior of these planet-sized pimples remain puzzling.

The magnetic dynamo

It is widely understood that the sun's magnetic field is generated by a magnetic dynamo in the star's interior. But exactly how this self-sustaining dynamo process is achieved is an ongoing area of research.

Challenging times

While visual indicators such as those describe can foretell the beginning of the 11-year cycle, accurately predicting the timing and intensity of the sun's solar activity showstopper still challenges experts.

The sun's chemical composition

The sun is mostly composed of the elements hydrogen and helium. What isn't known is their relative abundances. The exact chemical composition of the sun is, therefore, still under debate.

Mysteries of the solar eclipse

A solar eclipse offers a unique glimpse into the sun's dynamic behavior. The celestial spectacle offers a rare chance to gather data from Earth with unparalleled accuracy and detail.

When will the sun stop shining?

While scientists understand the sun's mass, age, size, and total irradiance reasonably well, what is uncertain is exactly when the sun will burn itself out. Most predictions point to it dying out in about five billion years' time when it runs out of hydrogen. Then what?