The eternal celestial clock ticks on year after year, millennium after millennium.
It was an unseasonably mild evening last May when I carried my telescope into the backyard. The warmth of the day still lingered, and the tangy scent of freshly mowed lawns mixed with the sweet perfume of a nearby lilac bush. The twilight glow in the west was strong enough to wash out all but a handful of the brightest stars. Still, I was anxious to start my hunt. I keyed off Castor and Pollux—two stars bright enough to easily punch through the dusk—and made a right-angle turn toward the horizon to Epsilon Geminorum. I nudged the scope westward a couple of degrees, and there it was, the object of my quest: 37 Geminorum.
The star isn’t much to look at, really—just a sixth-magnitude speck of light. Perhaps its greatest claim to fame is that it closely matches our Sun’s size, temperature, spectral classification and metallicity. Some speculate that those factors make 37 Gem a good place to look for life-bearing worlds, though no planets have been found orbiting it as yet. But as I gazed into my telescope last May, none of that mattered. The star held a much greater importance of a purely personal nature.
This year, 37 Gem serves as my “birthday star.” The starlight I saw in my scope’s eyepiece that night began its journey at about the same time I was born. It was quite a treat to consider that the modest glint I observed was from a stream of photons that had been travelling all my life, only to end their journey in my eye at that particular moment. It felt like a very special cosmic birthday present.
If you want to look up your own birthday star, the Internet makes it easy. Simply go here and you’ll find a series of tables that catalogue stars by distance in light-years—just pick a star whose proximity to our solar system matches your age. Because these stars are relatively nearby, their distances are generally known with a fairly high degree of accuracy.
The birthday-star idea is a neat one, but there are many other ways to see one’s lifespan marked by astronomical events. Our lifetimes are divvied up by the rotation of Earth (days) and by our planet’s motion around the Sun (years). But there are other, less obvious markers too. For example, I felt a touch of mortality one night recently as I gazed in awe at Saturn’s magnificent rings. This year, they’re displayed “fully open,” since one of the planet’s poles (the north one) is tilted Earthward by the maximum amount. We get to enjoy this perspective roughly once every 15 years, which means that if I manage to make it into my 80s—the average life expectancy of a Canadian male—I’ll see Saturn this way just twice more. That doesn’t seem nearly enough.
On another evening, I turned my attention to Jupiter, nicely positioned near the bright star Spica, in Virgo. Jupiter takes a little less than 12 years to orbit the Sun, so it’ll revisit Spica in 2029, 2040 and again in 2052. I was struck by a sense of melancholy when I realized I would be fortunate, indeed, to see this reunion three more times before I shuffle off this mortal coil.
Lest all this talk of mortality strikes you as slightly alarming, rest assured that the cosmos also offers great comfort and even a sort of immortality. As Carl Sagan famously noted, we’re all made of star-stuff. Most of the atoms in our bodies were manufactured deep in the hearts of massive stars and later dispersed throughout the galaxy by supernova explosions. Now that’s a birth!
In the grandest scheme of things, the bits of star-stuff I lay claim to were never really mine—I’m simply fortunate enough to utilize them for a very, very short while before passing them on. But I have to say that in the time I’ve been alive, I’ve grown quite fond of these particular atoms and can’t help having a vested interest in their future. Who knows what they’ll one day become! The mind boggles at the possibilities.