Editor's note: A version of this was previously published on the author's website.
Sometime in the early to mid-1960s, as a teenager on the American missile base at Kwajalein, Marshall Islands, I snorkeled beyond the drop-off on the lagoon side; this is the descending slope where the water gets deeper the farther you swim from the reef. The sandy bottom tilts gradually until suddenly it plunges. Beyond that, the lagoon is too deep to see the bottom. Shimmering dim green shafts of sunlight sliced down all around me, reaching farther and farther into the depths, until they nearly converged. Below them was nothing.
In my memory, the scene is silent — maybe it truly was, because I was far enough from where waves sloshed across the reef; more likely water glugged in my ears and lapped against my body and my snorkel whooshed quietly as I breathed, and I only remember it as deathly silent because of the chilling, frightening view. The sense of complete aloneness spooked me. Quickly, I paddled back to the familiar world of coral heads, sand, sea anemones and small darting fish.
The fear wasn’t only because I floated like a brine shrimp at the top of a saltwater aquarium, though that was true. It was triggered by isolation and a sense of the void.
Many feel an equivalent shiver when confronted by the thought of the endless vastness of space. Also contributing are the violence of exploding stars that blaze brighter than their entire galaxies, meteors and comets that could smash through the atmosphere, solar flares capable of knocking out satellites and power grids, colliding neutron stars, and black holes that merge with an unimaginable blast. Mostly it's the emptiness, I suspect.
I've had that goose-pimply impression walking in the desert while my telescope and camera make exposures. Flashlight off, I peer up at icy stars, the vague sweep of the Milky Way and blackness.
We can't comprehend the distance to another star besides the sun, as the void is too wide. The nearest, Proxima Centauri, is about 4.25 light-years off, as NASA points out. One light-year is 5.87 trillion miles. The distance to Proxima Centauri is close to 25 trillion miles. Another way to try and picture it is to realize that light travels 186,000 miles (7.4 times the circumference of Earth) per second, for every second in 4.25 years. That many years total more than 134 million seconds, during each one of them light has traveled as far as 7.4 times around the Earth, just to reach us from the closest star.
Voyager 1, a NASA spacecraft launched in 1977, reached Jupiter in 1979 and Saturn in 1980, and continues heading away from the sun. After 41 years it's cruising in interstellar space, nearly 13.5 billion miles away. Traveling at 10.3 miles per second, if it were headed to Proxima Centauri, it would arrive in 73,000 years.
The morning of April 2, 2011, I was taking astrophotos from a favorite site in Emery County in Utah. One of my subjects was the "Needle Galaxy," NGC 4565.
The Needle Galaxy is edge-on from our perspective, and astronomers believe it looks about as the Milky Way would if observed at a similar distance and orientation. Dust lanes are easy to see throughout the galaxy's plane, which cuts through the bright nucleus. This Astronomy Picture of the Day posting, from 2017, estimates its size as about 100,000 light-years across, like that of our home galaxy.
"At a distance of only about 40 million light-years, NGC 4565 is relatively close by, and being seen edge-on makes it a particularly useful object for comparative study," says a Hubble Space Telescope internet site. The "relatively close by" galaxy is more than 9.4 million times as far away as Proxima Centauri.
Also that morning I imaged a collection of galaxies in the constellation Leo called Copeland's Septet. The Kopernik Observatory and Science Center in Vestal, New York, notes that the compact group actually consists of eight, not seven, galaxies: NGC 3748, NGC 3745, NGC 3746, H57h, NGC 3754, NGC 3753, NGC 3750 and NGC 3751. The group, also known as Hickson 57, was named in the 19th century by Ralph Copeland, employed by the pioneering English astronomer William Parsons, third lord of Rosse, according to the observatory. In 2005, a supernova was discovered in NGC 3746, a lovely face-on spiral.
A large edge-on galaxy, NGC 3753, is interacting with the small galaxy directly above it, NGC 3754, causing distortion in spiral arms as stars are slung away. The Kopernik Observatory quotes professor Paul Hickson of the University of British Columbia, Vancouver, Canada — compiler of the "Atlas of Compact Groups of Galaxies" — as adding that NGC 3754 is a source of radio and infrared emissions.
The Copeland Septet galaxies seem to be about the same distance from Earth, 480 million light-years. Their starlight flashed across space for almost half a billion years without hitting anything until it reached my telescope. What a depth of nothingness.
Copeland's Septet is 112.9 million times as far away as Proxima Centauri — which is 73,000 years distant at Voyager 1 speed.3 comments on this story
Astronomy is exploration. Discovery requires a sense of adventure, some apprehension, a bushel of curiosity and a reasonable dose of humility. When we look into the depths of the night, we experience a frisson of excitement and loneliness, a sensation of fearful distances and cosmic events — distances, happenings and time scales that stretch our comprehension — and with them awe, reverence and spirituality.
For the serious astronomy devotee, these sensations are not only justified but may be inevitable.