Winter nights sparkle with some of the brightest stars in the sky: Rigel and Betelgeuse in Orion, Aldebaran in Taurus, and Procyon in Canis Minor, to name just a few. Yet it takes only a glance to pick out the brightest of them all: Sirius, the leading light of Canis Major, the big dog. That makes it the top dog. It’s in the southeast by mid-evening, and scoots low across the south during the night.

Sirius looks so bright in part because it is fairly bright — a couple of dozen times brighter than the Sun. But it also shows off because it’s just 8.6 light-years away. Only four other star systems are closer.

By astronomical standards, Sirius is just down the block. By human standards, though, the gap is pretty much incomprehensible — it’s far beyond any ordinary concept of “far away.”

To put it in everyday terms, the distance to Sirius is about 50 trillion miles — a five followed by 13 zeroes. To look at it another way, the farthest that any human has ever journeyed is the Moon. A one-way trip to Sirius would be equivalent to a hundred million round trips to the Moon.

At the speed of the fastest probe we’ve ever launched, it would take more than 150,000 years to get to the top dog. And even if you could streak toward Sirius at the speed of light — a zippy 670 million miles per hour — it would take 8.6 years to get there — hence the star’s distance: 8.6 light-years.

More about Canis Major tomorrow.

Script by Damond Benningfield

Support McDonald Observatory