How hot is the Sun in space?

How hot is it near the Sun? Try the distance calculator

Drag the slider to pick a distance from the Sun's visible surface. The calculator shows how hot a dark, flat surface facing the Sun would get at that distance, and how much stronger the sunlight is than at Earth.

Notice how little changes close in. Within 10,000 miles of the surface, the Sun fills nearly half your sky, so you'd feel almost the full 10,000°F. Heat falls off quickly after that: 1 million miles out it's around 5,200°F, still hotter than the melting point of steel (about 2,500°F), and by 10 million miles it's under 1,700°F.

The million-degree corona that wouldn't burn you

Here's the strangest part of how hot the Sun is in space. Parker Solar Probe flies through the corona, where gas is over a million degrees, yet its heat shield only reaches about 1,800°F. How?

Temperature measures how fast particles are moving. Heat is how much energy they can hand over. The corona's particles are extremely fast but incredibly sparse, billions of times thinner than the air at sea level, so very few ever strike the spacecraft. Almost all of the heating comes from direct sunlight, which is what the calculator above models.

How hot did Parker Solar Probe get?

On December 24, 2024, NASA's Parker Solar Probe passed 3.8 million miles (6.1 million km) from the Sun's surface, the closest any human-made object has ever come to a star, moving at about 430,000 mph. If the Earth–Sun distance were a football field, Parker was about four yards from the end zone. It repeated passes at that distance through 2025.

Why is 1,800°F lower than the calculator's 2,861°F at the same distance? The shield's front is coated with a bright white ceramic that reflects much of the sunlight, and it radiates heat from both sides. The calculator assumes a black surface that absorbs everything. Parker's solar panels, which are only partly exposed, are cooled by circulating water.

How hot does sunlight make the planets and the Moon?

The same Sun heats every world, but distance, air and spin decide how hot it gets. Here are the highest daytime surface temperatures.

• Mercury's sun side reaches about 800°F (430°C), while its night side drops to about −290°F (−180°C). With no air to hold heat, the difference is extreme.
• Venus is about 900°F (475°C) everywhere, day and night, the hottest planet in the solar system.
• The Moon, when the Sun hits it, heats to about 250°F (121°C), then falls to about −208°F (−133°C) at night. That's the same 250°F our calculator predicts at Earth's distance, because the Moon has no atmosphere. The Sun seen from the Moon looks white, not yellow.
• Mars gets less than half Earth's sunlight. Near its equator in summer the ground can reach about 70°F (20°C), but nights fall to around −225°F (−153°C).

How hot is the Sun outside Earth's atmosphere and in low Earth orbit?

Above the atmosphere, sunlight delivers about 1,361 watts per square meter, a value called the solar constant. At the ground on a clear day at noon, it's closer to 1,000 watts per square meter, because air absorbs and scatters the rest. That's why sunlight in space feels harsher: there's more of it, including ultraviolet light the ozone layer normally blocks.

With no air to spread heat around, things in low Earth orbit swing wildly. Surfaces on the International Space Station can range from about 250°F (121°C) in direct sunlight to about −250°F (−157°C) in shadow, and the station passes between the two every 90 minutes as it circles Earth. Astronauts' spacesuits and the station's radiators exist largely to manage that swing.

Could you touch the Sun or get close to it?

No. The Sun has no solid surface to touch: it's plasma all the way down, getting denser and hotter with depth. Any spacecraft, rock or metal would be vaporized long before reaching the 10,000°F photosphere. Even Parker Solar Probe, the most heat-resistant spacecraft ever built, keeps more than 3.8 million miles away.