about 2 million K

Within the radiative zone, the solar material is hot and dense enough that thermal radiation transfers the heat of the core outward through the Sun. The core of the Sun is where nuclear fusion reactions are happening – protons are merged together to create atoms of helium.

Outside of the core is the radiative zone where energy is transported by radiation. According to the Contemporary Physics Education Project’s sun information, “It becomes less efficient for energy to move by radiation, and heat energy starts to build up at the outside of the radiative zone.

The photons of energy have finally, after 100,000 years, come to the end of their journey inside the Sun. They have now reached a zone which is transparent to light. The photons escape into space, and travel at the classic speed of light — around 300,000 kilometres per second.

Eventually, photons along the entire magnetic spectrum exist in the radiative zone. It takes them about 10 million years to escape.

That means that the typical distance between protons or electrons is about (10^26)^1/3 = 2 x 10^-9 centimeters. The actual ‘mean free path’ for radiation is closer to 1 centimeter after electromagnetic effects are included. Light travels this distance in about 3 x 10^-11 seconds.

50 million years

Eruptions on the sun’s surface are probably caused by giant, unstable magnetic plasma arches, a new study reports — a discovery that brings scientists one step closer to predicting solar outbursts that can wreak havoc on Earth.

Sunspots appear dark (in visible light) because they are much cooler than the rest of the surface of the Sun. Sunspots have temperatures around 6,300 Fahrenheit (~3,500 Celsius) while the surrounding surface of the sun has a temperature of about 10,000 Fahrenheit (5,500 Celsius).

Sunspots are dark, planet-sized regions that appear on the “surface” of the Sun. Sunspots are “dark” because they are cooler than their surroundings. Sunspots are caused by disturbances in the Sun’s magnetic field welling up to the photosphere, the Sun’s visible “surface”.

Sunspots generally appear in opposite-polarity pairs or in opposite-polarity groups when the magnetic field is fractured. And sometimes the magnetic field can emerge to the surface fractured and tangled, leading to a great and confusing sunspot group.

As the Sun rotates, the magnetic loops wrap tigher and tighter (and get more and more twisted and complicated) until the magnetic field is wound up so tight that the fields (“rubber bands”) snap! Where the magnetic field snaps is where active regions (and hence sunspots) on the Sun form.

Our star is powered by nuclear fusion, and it turns hydrogen into helium in a process that converts mass into energy. Once the fuel supply is gone, the sun will start growing dramatically. Its outer layers will expand until they engulf much of the solar system, as it becomes what astronomers call a red giant.

If sunspots are active, more solar flares will result creating an increase in geomagnetic storm activity for Earth. Therefore during sunspot maximums, the Earth will see an increase in the Northern and Southern Lights and a possible disruption in radio transmissions and power grids.