How Hot Is the Sun? Surface and Core Temperature
Note: the labels in the image are in Turkish – Çekirdek = core, Yüzey (fotosfer) = surface (photosphere), Taç (korona) = corona.
Temperature inside and outside the Sun
| Layer | Approximate temperature | Description |
|---|---|---|
| Core (inside) | 15 million °C / 27 million °F | Where the Sun’s energy is produced |
| Surface – photosphere (outside) | 5,500 °C / 10,000 °F | The layer that emits the light we see |
| Corona | up to 2 million °C / 3.5 million °F | Outer atmosphere, visible during a total solar eclipse |
Why is the Sun so hot?
The Sun is a glowing ball of hot gas (plasma) made mostly of hydrogen and helium. It does not burn like a fire: under the enormous pressure and temperature of the core, hydrogen nuclei fuse into helium. The energy released by this nuclear fusion is the source of the Sun’s light and heat.
Key facts about the Sun
- Distance from Earth: about 150 million km (93 million miles); sunlight reaches Earth in about 8 minutes 20 seconds.
- Diameter: about 1.4 million km; about 1.3 million Earths would fit inside it.
- Age: about 4.5 billion years; a yellow dwarf star.
- Mass: more than 330,000 times the mass of Earth.
Frequently asked questions
How hot is the Sun?
The Sun’s surface is about 5,500 °C (10,000 °F) and its core is about 15 million °C (27 million °F). Its outer atmosphere, the corona, can reach 2 million °C.
What is the temperature of the Sun’s surface?
The photosphere, the Sun’s visible surface, is about 5,500 °C (10,000 °F).
What is the temperature of the Sun’s core?
The Sun’s core is about 15 million °C (27 million °F). At this temperature hydrogen nuclei fuse into helium.
Why is the corona hotter than the surface?
The corona reaches up to 2 million °C while the surface is about 5,500 °C. Scientists think magnetic energy carried up from below heats the corona; the exact mechanism is still being studied by missions such as NASA’s Parker Solar Probe.
How long does sunlight take to reach Earth?
Because the Sun is about 150 million km away, its light takes about 8 minutes 20 seconds to reach Earth.
Source: NASA – Sun: Facts
