Oumuamua makes its way through the Solar System
Last month, I told you about a new type of astronomy, one that uses Gravitational Waves to view cataclysmic events happening across the universe. This month, we’ve got news from old-school astronomers about a strange visitor from another star…the first ever confirmed interstellar object: Oumuamua! (Pronounced, “Oh Mooa Mooa,” this is a Hawaiian word meaning “scout” or “messenger.”)
Oumuamua was discovered on October 19th of this year by the folks at the Pan-STARRS telescope on the island of Maui. At first they thought it was a comet that, like all other comets, had been shaken loose from the Oort cloud at the edge of our solar system. But, given that no tail developed as it rounded the Sun, it became clear that it was a rocky asteroid and not a a comet.
Okay, so, it’s an asteroid, and not a comet. That’s fair. But how do we know it’s not from our solar system? There are three key bits of evidence that bear this out:
First is its shape. Oumuamua is shaped unlike any other asteroid (or comet) that we’ve seen before. It’s basically a long, cigar-shaped object that’s 40 meters wide and 400 meters long. Sort of like a big, rocky splinter tumbling through space. Pretty much every other asteroid we’ve seen in the past has been more or less ball-shaped and even the few that were shaped like Oumuamua were nowhere near as elongated.
Second, Oumuamua is traveling fast. Like, really fast. Fast enough to escape the gravitational pull of the Sun! When it passed the Sun it was going over 87 kilometers per second! Which was more than fast enough to escape the Sun’s gravity and head back out into interstellar space.
Finally, the direction of Oumuamua’s approach towards the Sun is completely unlike any other asteroid or comet. Pretty much everything we’ve observed in the past in our solar system takes place in the same plane as the orbits of the planets.
To visualize this plane, imagine the solar system as an old LP record with the Sun at the center and all the planets sitting on the various grooves of the record. But Oumuamua came in from a direction that’s almost perpendicular to the orbits or the planets!
To recap: Weird shape, traveling fast enough to escape the biggest object in the neighborhood and coming from a completely unexpected direction…yeah, odds are really good that it’s not from around here. Once all the evidence was put together, they even created a new designation for objects of this type, and officially labeled it “1I/2017 U1”. The “I” at the front is for “interstellar,” and this is the first interstellar object, ever.Now, if, like myself, you are a reader of science fiction, this whole thing sounds really familiar. In fact, it sounds just like the plot for Arthur C. Clarke’s “Rendezvous With Rama”.
In that (awesome) book, a huge, cylindrical alien ship (which is nicknamed “Rama,” after the Hindu god) comes tearing through our solar system, using the Sun for a gravity assist as it heads out for parts unknown. A team of astronauts is sent to meet the craft, find their way inside and are faced with one challenge after another as the heat of the Sun warms up the interior and brings its systems back to life. (Seriously, it’s an amazing book, and I’m shocked that Hollywood hasn’t picked it clean yet.)
With that in mind, various radio telescopes around the world have begun to listen to Oumuamua to see if there are any signals coming from it. At this point, they haven’t heard anything indicating that Oumuamua is something other than a lonely rock hurtling through the void. But, it’s early days yet, and they’ve just begun to sift through the mountains of data that have been collected.
And it’s likely that that Oumuamua won’t be the last interstellar visitor that we’ll see in the months and years to come. Pan-STARRS is a relatively new telescope, and newer more sensitive devices will soon be scanning the sky along with it, hopefully alerting us to even more strange and wonderful visitors from other stars.
Steven W. Disbrow is a programmer who specializes in e-commerce and mobile systems development, an entrepreneur, comic-book nerd, writer, improviser, actor, sometime television personality and parent of two human children.