How does the Sun affect us?

The seasons of the year give us a good example of how the sun affects the Earth. Temperatures depend mostly upon how the rays of the Sun strike the surface of the Earth. At the equator, the rays of the sun strike the ground directly, while at latitudes away from the equator, the rays of the Sun strike the ground more obliquely. This is the principal reason why areas at the equator are warmer than areas north or south of it.

The Earth rotates about its axis, which is inclined 23.5° to the plane that contains the centres of the Earth and the Sun. This is the main cause of the seasons. For instance, in its summer, the Northern Hemisphere is oriented more toward the Sun, so the Sun rises higher in the sky, its rays strike the surface more directly, and days are longer. The opposite situation occurs in winter.

Sun showing sunspots. Photo: NASA/Goddard SFC.

Storms sometimes rage on the sun and produce strong radiation that affects the Earth, such as in the disturbance of radio communications. Sunspots are another important phenomenon. A sunspot is an area of the surface of the Sun that is cooler than its surroundings. A sunspot may be at a temperature of 4000 degrees Celsius, while the surrounding solar surface is at 6000 degrees. So we can see sunspots from the Earth.

With favourable conditions, such as at sunset in ideal atmospheric conditions, sunspots can be seen with the naked eye. But be careful, as looking directly at the sun is hazardous, even when wearing dark sunglasses.

Scientists speculate on the effects of sunspots on the Earth’s climate. Research has shown that in periods of low sunspot activity, the average climate is colder than during periods of high sunspot activity. Toward the end of the 20th century, sunspot activity was high, and the Earth’s climate was warmer than it had been for a long time.