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Watoga Trail Report

Artists conception of Oumuamua. Courtesy of NASA Science, European Southern Observatory, K. Kornmesser

An astronomical
mystery – literally
“A messenger from afar
arriving first.”

There is only one word in the Hawaiian language for this apt description of the first detected interstellar visitor to our solar system, Oumuamua – Oh- Moo-eh Moo-eh.

Scientists on duty at the Pan-Starrs1 telescope on Mount Haleakala in Hawaii first detected Oumuamua on October 19, 2017. By that time, the unusual and un-identified object was well into our solar system and nearing the sun.

Before we dig further into the facts and speculations about Oumuamua, allow me to make a statement regarding this article’s intent.

It is not a paper intended for peer review in a scientific journal, nor is it a “woo woo” piece. This dispatch is aimed squarely at folks like myself, average citizens wishing to be informed about new visitors to our cozy little home here in a minor spiral arm of the Milky Way Galaxy.

On its detection merits alone, this is a fascinating story about science’s ability to recognize an interstellar visitor to our solar system, and to be able to distinguish Oumuamua from the thousands of other similar Near-Earth Objects that routinely orbit our sun.

Oumuamua is an object so unique in its atypical features that the public will want to know all about it. At least, I sincerely hope that is the case.

In parsing through many articles from reputable journals about the nature of Oumuamua, I decided not to ignore any information sources that appeared to stay within the border of mainstream science.

Likewise, I included a minority opinion of the possible nature of Oumuamua because the sources are from credible scientists published in prestigious science journals. This controversial suggestion will be in the next installment of the Watoga Trail Report, right alongside what I feel is a more mainstream hypothesis of the still-unidentified cosmic traveler.

I felt it necessary to share varying opinions and speculations with our readers that come from equally reputable sources. But that is what honest journalism is all about – we provide you with facts as we understand them. At the same time, you decide what to believe based upon what sounds most reasonable and the opinions of those who study these things.

For credible information about the cosmos, we turn to astronomers and astrophysicists. Should you need brain surgery, it would be foolish to consult your mechanic, right?

So, what makes Oumuamua so interesting?

Let’s discuss what facts we do know about Oumuamua. Particularly those that have astronomers all over the world engaging in diverse speculation. And when a scientist speculates on nearly anything, it is generally based upon available data. 

Unlike me speculating on what kind of morel season we will have this year based solely upon the bushiness of squirrel tails – there is no correlation; therefore, it is not science. It is folklore!

First, there is continuing debate as to the general shape of Oumuamua.

Remember, we didn’t see Oumuamua clearly; it appeared on the most powerful telescopes as a point of light. However, we do know that it is reddish and elongated. And we have no photos of it, so its geometry has to be determined by its reflection as it rotates. 

We can determine some information about the shape of an object by its light curve. The light curve measures light reflected from an object as a function of time. From the results, a general approximation of the shape emerges.

The light curve also reveals the rate of rotation, which is about 7.3 hours for Oumuamua. (Although discussion continues about which axis or axes Oumuamua is rotating. Several sources indicated it is tumbling.) 

Many scientists interpret the results of the light curve as indicating a cigar shape.

Yet, others have determined that Oumuamua is flat, like a pancake. They base this on the fact that the amount of light reflected at peak reflectivity is 10 times what has previously been seen in asteroids that are generally irregularly shaped and occasionally spherical.

Another unique thing about Oumuamua is the aspect ratio is 10:1, meaning that it is 10 times longer than it is wide. this is something else we have not previously seen in an asteroid.

So, if the object is a quarter-mile long, as some sources claim, its width is about 132 feet. Most Near-Earth Objects, such as asteroids, have an aspect ratio of 3:1.

At first, Oumuamua was thought to be a comet, based on its behavior in regard to acceleration. But it was later determined to have none of the other signature characteristics of a comet.

Comets are composed primarily of ice, dust and rock. When approaching the sun, the ice in a comet vaporizes (sublimates), leaving a visible tail called a coma, often resulting in an increase in velocity due to the outgassing.

Asteroids, on the other hand, usually remain solid even when near the sun. Asteroids are generally rocky material, sometimes permeated with metals. This fact pushed the identity of Oumuamua as an asteroid to the top of the list quite quickly.

But Oumuamua’s geometry, reflectivity, and apparent acceleration away from the sun’s gravitational pull (non-gravitational acceleration) have not been observed in any asteroid to date.

So, why should we care?

Well, for starters, when a stranger visits our solar system unannounced and then slingshots past our sun at what NASA calls a “blistering speed” of 196,200 miles per hour relative to the sun, and leaves without further adieu; maybe we should be curious about it.

Oumuamua is now too far away to allow further study unless, as proposed by some, we chase it down. Due to its velocity, that’s not likely to happen. So scientists are limited to the data collected during its relatively brief pass- age through our solar system.

Unlike Near-Earth Objects that return regularly, Oumuamua arrived, got the scientific community in an uproar, and left, never to return.

In next week’s Watoga Trail Report, we will get a little closer to the nature of Oumuamua by consulting other sources. We’ll delve into a Harvard professor’s rationale for suggesting that our visitor may be artificial and not natural at all. A sort of “message in a bottle” explanation.

We will also consider some alternative explanations of Oumuamua, including speculations that it is a giant cosmic “dust bunny” or possibly, even, a hydrogen iceberg. The image of those two exotic objects wandering around in deep space should stir the imagination of the most unimaginative among us. 

We will conclude our investigation of Oumuamua by tapping a higher level of expertise a little closer to home. The principal scientist at the Green Bank Observatory right here in Pocahontas County will provide us with an articulate look at our solar system, and how intermittent visitors from outside can teach us about our greater home in the cosmos, the Milky Way Galaxy.

And, just maybe, put much of Oumuamua’s mystery to rest.

Please tune in next week to the Watoga Trail Report.

Ken Springer
Ken1949bongo@gmail.com

All citations available at email address above.

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