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The Sun: It's a Scorcher

Even though it is 93 million miles away from Earth, the Sun has a powerful influence on our planet. Not only is sunlight the ingredient that allows life to flourish, it also plays a critical role in determining the weather and climate of our world.

The Sun is a star that is so close to Earth that when it is over our heads, flooding the sky with light, the glow from all other stars cannot be seen. Made of hot gasses, the Sun is about 1.4 million km (900,000 miles) across and is at least 10 million degrees at its center.

Heat travels in all directions from the Sun and is the ultimate source of all energy on Earth. This energy is responsible for all sorts of weather events, not only scorching heat waves. For instance, wind occurs when sunlight heats the ground, which heats the air above it, which rises, so that cool air whisks in to take its place. The Sun is an integral part of the water cycle as well. Water evaporates from oceans as sunlight warms the water surface and forms clouds that may eventually cause a downpour.

The Sun also affects our world over longer time scales. Each year, the seasons change depending on the amount of sunlight reaching the surface and the Earth's tilt as it revolves around the sun. Summer occurs when a hemisphere is tilted towards the sun, and winter occurs when a hemisphere is tilted away from the sun. Over much longer time scales, changes in the amount of the Sun's energy that gets to Earth, because of changes in Earth's orbit, have contributed to the climate changes that caused ice ages in the past few million years.

Delve Deeper...

More information about the Sun from NCAR’s High Altitude Observatory

More information about the Sun from UCAR’s Windows to the Universe