The Sun's outer atmosphere is hotter than its surface
In short: It defies common logic: the Sun's outer atmosphere, the corona, is significantly hotter than its surface. While the photosphere sits at a searing 10,000 °F, the corona reaches temperatures of 3.5 million °F. This thermal mystery remains one of the biggest puzzles in heliophysics today.
Acting as our solar system's primary gravitational centre, the Sun is a yellow dwarf star aged 4.5 billion years. While it appears as a steady source of light from Earth, it is a dynamic entity. Its core is the engine of the solar system, where thermonuclear reactions generate extreme energy at temperatures exceeding 27 million °F (15 million °C). From this core, energy travels through the radiative zone—a process so slow it takes more than 170,000 years to move outward—before reaching the convection zone, where gas currents carry heat toward the surface.
The surface we see, known as the photosphere, is relatively cool at 10,000 °F (5,500 °C). However, the corona—the Sun's outer atmosphere—presents a paradox: it gets hotter as it stretches further away from the surface, reaching up to 3.5 million °F (2 million °C). This atmosphere is composed of ionized elements that glow in x-ray and extreme ultraviolet wavelengths, which allows NASA instruments to image it more clearly than the dimmer photosphere.
Understanding these layers is central to heliophysics. Scientists study these mechanisms to better understand distant stars, some of which are up to 100 times larger than our Sun. By observing features like coronal streamers—plasma shaped by magnetic field lines into tapered forms extending millions of miles—and prominences that eject material into space, researchers can decode the complex magnetic and thermal interactions that govern our nearest star.
Opens the Intellect+ feed with this card first. Swipe up for the next one.
Sources
- Summary by Intellect · source: What NASA Found Inside The Sun
- Also: Sun: Facts - NASA Science
- Also: NASA — Anatomy of the Sun - NASA
To cite this card, link to https://intellectplus.co.uk/app/space-what-nasa-found-inside-the-sun.
How we source, check and correct cards: Editorial standards.
General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.
Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?
Related
More in Sun & solar physics · More in Space · Latest · A–Z · All topics
