The Closest Star

by Karen A. Bellenir

When I lead tours of the night sky, I like to ask participants "Can you name the closest star to the earth?"

In the winter, some people guess Sirius. It catches a lot of attention because it shines as the brightest of all the stars in the night. And, from our vantage point in the northern hemisphere, it does hold the distinction of being the closest visible star to our solar system.

Another popular guess is Alpha Centauri. Some people even know that Alpha Centauri isn't just a single star. It's a multiple star system. They confidently tell me that Proxima Centauri is the closest star to the earth.

I give partial credit for this answer. Proxima Centauri, at four and a quarter light years away from us, is indeed the closest known star to our solar system.

But that's not quite what I asked. The star nearest earth is much closer. It isn't light years away. In fact, measured by the speed of light, it is a mere eight minutes away. That star is our sun.

Eight light minutes doesn't sound like a lot. Admittedly, compared with other objects whose distances are measured with astronomical scales, it is extremely close by. But on a human scale, the sun is incredibly far away: 93,000,000 miles. Ninety-three million is a number that can be mentally processed, but most people can't relate to the distance in an intuitive way. It usually works better to describe it through comparative models. Here are some of my favorites:

  • If you created a chain of earths, it would take 11,740 of them to stretch all the way to the sun.
  • If you drove to the sun in a car, traveling at a constant speed of 60 miles per hour and didn't ever stop for gas, rest areas, or local attractions, it would take you 177 years to get there.
  • If you had the power to shrink the solar system while keeping everything proportional and you used that power to reduce the earth to the size of a six-inch ball, the sun would still be more than a mile away. It would still also be big. On a scale where the earth is a mere six inches in diameter, the sun would be as large as a five-story building.

The August 2014 issue of the Pier Press newsletter, Observations, includes more information about the sun and has links to images and additional facts. If you missed it you can access an archived copy here. While you're on that page, be sure to subscribe to Observations so you don't miss future editions. Subscriptions are free.