The Sun is a star, just like the stars we see at night. The Sun is much closer to us than the other stars, so it appears much bigger and brighter. The Sun’s visible disk is called the photosphere. Surrounding the photosphere is a thin layer called the chromosphere, which is only seen during a total solar eclipse. The outer atmosphere of the Sun is called the corona.

Eclipses of the sun inspire creative works and cultural rituals. One rock-climbing performance group from Canada performed a piece during the solar eclipse of May 1994.

The basics

Period of revolution (around centre of galaxy): 220 000 000 years
Period of rotation 27 days on average
Diameter: 1 392 000 km
Surface gravity: 27.9 times greater than Earth’s
Composition: 75% hydrogen, 25% helium, with traces of heavier elements
Temperature: 5 500 degrees Celsius at surface; 15 000 000 degrees Celsius at core

Appearance in Earth’s sky

The Sun appears as a blindingly bright disk of light. In fact, the Sun is bright enough to cause serious eye damage, so it’s important never to look at it directly. When the Sun is in the sky, the atmosphere of the Earth scatters the blue component of the Sun’s light, turning the sky blue. This blue sky is bright enough that we cannot see the other stars in the sky. (The stars are still there, however, and can be seen in the daytime during a solar eclipse.)

Telescopic appearance

The Sun is so bright that looking at it through a telescope for even an instant can cause permanent blindness. The best way to observe the Sun is by using a pinhole camera or another indirect viewing method. The most obvious features of the solar disk are sunspots. These are cooler regions of the Sun’s surface and are sometimes visible as dark spots. The Sun rotates relatively slowly, once every 27 days.
Canadian Heritage Information Network
Australian Museums & Galleries Online, Australia; Centre of the Universe; Gemini Observatory, Hawaii; Glenbow Museum; The Manitoba Museum; National Research Council Canada; Planétarium de Montréal

© Canadian Heritage Information Network 2003

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