What is Star?

The sun is a star, a hot ball of glowing gases at the heart of our solar system. Its influence extends far beyond the orbits of distant Neptune and Pluto. Without the sun's intense energy and heat, there would be no life on Earth. And though it is special to us, there are billions of stars like our sun scattered across the Milky Way galaxy. If the sun were as tall as a typical front door, the Earth would be the size of a U.S. nickel. The temperature at the sun's core is about 27 million degrees Fahrenheit.

Average diameter: 864,000 miles, about 109 times the size of the Earth.

Rotation period at equator: About 27 days.

Rotation period at poles: About 36 days.

Surface temperature: 10,000 degrees Fahrenheit.

Composition: Hydrogen, helium.

The Solar Wind Across Our Solar System

The Sun releases a constant stream of particles and magnetic fields called the solar wind. This solar wind slams worlds across the solar system with particles and radiation – which can stream all the way to planetary surfaces unless thwarted by an atmosphere, magnetic field, or both.

Earth

The solar wind is mostly deflected by our magnetic field, but sometimes, when intense, some of it can leak through. Once in near-Earth space, the particles can trigger aurora near the poles.

Earth's Moon

Because its atmosphere is so thin, the solar wind hits the Moon’s surface directly, with just a little bit of deflection by small bubbles of magnetic field scattered across the surface. This bombardment deposits ingredients that could make water.

Asteroids

An asteroid has no inherent protection around it, so the solar wind can easily batter its surface. The incoming particles sometimes kick material off into space, changing the fundamental chemistry of what’s left on the ground.

Comets

Comets have a sort of atmosphere, called a coma. It's created as the comet’s frozen ices turn to gas by the Sun’s heat. Some of those gas particles become charged in the intense sunlight. Once that happens, they move in concert with the magnetized solar wind, forming what we see as the comet's trailing ion tail.

Mars

When the solar wind crashes into Mars' atmosphere, all that energy creates a layer of electrified particles called an ionopause, which, in turn, also helps shield the surface from solar wind.

Jupiter

Jupiter's magnetic field is similar to Earth's, but much, much larger. This magnetic field creates a bubble that directs the solar wind to stream around the planet.