Copyright ©2025
by Ralph F. Couey
One of the things that has been learned about the universe is that it is neither quiet nor static. Somewhere out there, stars explode, black holes form and merge, asteroids and comets streak through the void. The more that is discovered, the more we realize what a busy place it is.
Up until 2017, what we saw in the sky, other than stars, was assumed to originate locally, that is, from our own solar system. But that year, a new object was discovered, one that, when its trajectory and speed were analyzed, wasn't local in origin. It had originated from outside our solar system, the first such object discovered. Because it was found by one of the telescopes on top of a volcano in Hawai'i, it was named "'1I/Oumuamua," Hawai'ian for "messenger from afar arriving first." The 1I marked it as the first object known to come from interstellar space. It got a lot of attention, not only because it was the first extrasolar visitor, but because of its elongated shape. Some people believed, and still do, that it was actually a ship from some distant civilization on a voyage of discovery. After a lot of observation and study, it was suggested that 'Oumuamua was neither an asteroid nor a comet, but perhaps a piece of a destroyed exoplanet similar to Pluto.
It was thought that this was a once-in-a-lifetime event. But two years later, another object came streaking in from the outer darkness. This one was given the less poetic name "2I/Borisov," 2I being the second interstellar object found. This one was absolutely a comet, with the requisite coma and tail. Now, a third interstellar object, "3I/Atlas," has been discovered. Its trajectory suggests its point of origin was the crowded center of the Milky Way galaxy, and could be as much as 14.6 billion years old. That's astonishing, because it dates this comet back to the very beginning of the Milky Way's formation, and perhaps close to the beginning of the universe itself.
Another surprise was Atlas' apparent size, initially thought to be about 6.5 miles wide, roughly the same size as the Chicxulub impactor that exterminated the dinosaurs. Recent data reduces it to about 3.5 miles wide, although this is still sufficiently large to wreak life-altering damage to Earth. That there are objects out there about that same size that we don't yet know about, at least gives me pause.
Our solar system has two structures, the Kuiper Belt and the Oort Cloud, which contain debris left over from the system's formation, including both rocky asteroids and icy comets. Most of those objects are in stable orbits. But the gravity of an occasional passing distant star, or a collision between two objects, can disrupt their orbits and send them plummeting inwards to the inner solar system. This is the doomsday scenario that has driven a lot of science fiction, written and broadcast, over the years. None of the three visitors poses a threat to Earth, but for example, 'Oumuamua wasn't found until it had already circled the sun and began to head back out to deep space. Ideally, you'd want them found before they got in that close to the Sun, but it apparently doesn't work that way all the time. These objects are familiar, as they share with Earth the same origin. The elements that make up those objects are usually the same elements found on Earth.
Apocalypse aside, these objects represent an incredible scientific opportunity. For the first time, scientists can analyze objects that don't originate from our cosmic zip code. All three of them can tell us volumes about what space is like far, far away, someplace we could never visit, either with humans or spacecraft. There are still outstanding questions about the formation of the universe and everything within it. Knowing what such objects are made of can lead to answers. And also to a lot of additional questions. And some feel that somewhere out there lies the answer to the most profound question: are we alone?
Right now, we don't have the money or the technology to place probes on these objects, or at least in a close orbit, and track them along their journey. Their incredible speed would take them places the Voyagers and Pioneer X won't reach for tens of millennia. What a ride that would be!
Some view such discoveries as pointless. They won't improve investments, pay the bills, buy groceries, change the weather forecast, or improve the odds of your football team. But what such knowledge does do is feed the insatiable curiosity that so defines humanity. The desire to know, to understand, is central to our very existence, dating to the first time ancient humans looked to the sky with wonder, awe, and amazement. There is still much to learn, so we will continue to seek answers to those questions that may now seem unanswerable.
And perhaps, someday we actually may discover what our place is in the universe.
