Because of the Earth’s tilt the sun’s rays strike the surface at a slant at the poles; they are less focused. The tilt of the Earth causes different areas to receive different amounts of solar energy. The difference in solar energy received at different latitudes drives atmospheric circulation.

The Short Answer: Earth’s tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun’s most direct rays. So, when the North Pole tilts toward the Sun, it’s summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it’s winter in the Northern Hemisphere.

Different areas also receive different amounts of sunlight in different seasons. The seasons are caused by the direction Earth’s axis is pointing relative to the Sun. The Earth revolves around the Sun once each year and spins on its axis of rotation once each day.

Tilt causes a change in the Earth’s orientation to the sun. As this orientation changes, solar altitude and length of day change too.

The traditional linking of birthdays and birth signs suggests the Sun spends about 30 days crossing each of the 12 zodiacal constellations. Actually, there is a lot of variation. Each year the Sun spends the most time in Virgo (more than 40 days) but only about a week within the boundary of Scorpius.

The Sun reaches its highest point at a variety of times as the seasons change, not merely at noon every day. The reason for this is largely due to the second main contributor to the Sun’s apparent motion throughout the year: Earth’s orbit around the Sun is elliptical, not circular.

Time of day: UV rays are strongest in the middle of the day, between 10 am and 4 pm.

The summer solstice for the northern hemisphere occurs within a few days of June 21 every year. It is on this day that the position of the Sun in the sky at noon is at its highest altitude of the year, and the position of the Sun at Sunrise and Sunset is farthest north for the year.

Exact date varies with latitude solstice At 40 degrees north latitude – the latitude of, say, Philadelphia in Pennsylvania, the Mediterranean Sea and northern Japan – the earliest sunrise of the year happens on or near June 14. For that same latitude, the latest sunset of the year falls on or near June 27.

Northern hemisphere

UV radiation is usually strongest for a few hours around noon and less strong during the early morning and the late afternoon/evening (see Figure 1).

Earth is closest to the sun every year in early January, when it’s winter for the Northern Hemisphere. We’re farthest away from the sun in early July, during our Northern Hemisphere summer.

Our sun’s death is a long way off — about 4.5 billion years, give or take — but someday it’s going to happen, and what then for our solar system? The trouble begins before the death proper: The first thing we have to contend with is the elderly sun itself.

Nothing is more important to us on Earth than the Sun. Without the Sun’s heat and light, the Earth would be a lifeless ball of ice-coated rock. The Sun warms our seas, stirs our atmosphere, generates our weather patterns, and gives energy to the growing green plants that provide the food and oxygen for life on Earth.

It is the pull of the Moon’s gravity on the Earth that holds our planet in place. Without the Moon stabilising our tilt, it is possible that the Earth’s tilt could vary wildly. It would move from no tilt (which means no seasons) to a large tilt (which means extreme weather and even ice ages).

eight minutes and twenty seconds

If the sun suddenly blew up, we actually wouldn’t know it happened for — you guessed it — eight minutes, 20 seconds — since even that explosive light show would only be traveling, at maximum, the speed of light. The death and destruction would follow very, very shortly after that.