The Sun, An Ordinary Yet Extraordinary Star

The sun pokes out of a layer of fog over Lake Superior at sunrise in Duluth this morning (Aug. 8). Bob King

Sometimes I have to remind myself that the sun is a star. It seems so singular, so incredible. Our planet turns to face it every day, so it’s easy to take for granted. But every so often I look up and take a quick, wincing look at that glaring disk. Feel the intensity of its heat on my skin. And realize how incredibly special it is to be close neighbors with a real star. Just like the ones we see twinkling on clear nights.

Nighttime stars shed no heat you and I can feel, and none are close enough to show a disk except in large instruments using special techniques. But they’re all stars just like the sun, and if we could magically bring them closer, we’d sure as summer get a sunburn. The sun is their representative and for us, a gift and a privilege.

The sun is a luminous ball of hydrogen and helium gas held together by its own gravity. Within its hot, pressurized core hydrogen fuses with other hydrogen atoms in a controlled thermonuclear reaction that creates helium atoms at the same time releasing energy. That energy takes about 170,000 years to travel the distance from the core to the surface, where it’s released as heat and light. Lsmpascal

The sun is 93 million miles away and the largest thing in the solar system. It would take 330,000 Earths to equal the mass of the sun. As the most massive thing around, its gravitational force holds the solar system together. Remove the sun and all the planets, comets and asteroids would fly off into space never to be reunited.

Astronomers classify the sun as a G2 yellow dwarf. Although blindingly white when viewed from above the atmosphere, its true spectral color is yellow-white: hotter stars appear bluer, cooler ones redder. And while the sun is on the small side when compared with supergiants like Betelgeuse, it’s larger than the vast majority of stars, the red dwarfs, which possess as little as 7% the mass of the sun.

This is an example of a Hertzsprung-Russell diagram; a plot of luminosity (similar to brightness) versus color. The diagonal band labelled “main sequence” is where dwarf stars such as the sun spend most of their active lifespan. Red giants and supergiants are evolved stars with masses greater than red dwarfs. White dwarfs are small and dim compared to red giants but dense and hot. Wikipedia / CC SA-3.0

Stars like the sun represent 1 out of every 13 stars in the galaxy. They’re modest, hydrogen-burning stars in the prime of their life. Earth is fortunate to be located at the right distance from our star for its energy to have empowered molecules to join together several billion years ago to make the first living things. From these simple beginnings life has became incredibly diverse and more complex, eventually giving rise to a species that drives cars and pays taxes.

The rising sun reveals a blanket of fog covering Lake Superior in Duluth this morning. Bob King

The heat that makes us sweat during the Dog Days of August originates from thermonuclear fusion reactions deep within the sun’s 27,000,000° F core. We complain about hot days but trillions of atoms and tens of thousands of years of time go into the heat we easily wish away. Many of us are barely aware of how important the sun is to our existence. Without it, there’d be no us.

And if that’s not enough, the sun provides Earth’s inhabitants with sunrises and sunsets, which most of us consider one of the most beautiful sights on the planet. Nothing else combines the essential and the aesthetic like the sun. So this is what a real star is.

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