Of Alien Megastructures

They call it Tabby’s star. It is a main sequence star quite similar to our Sun, and is about 1500 light years away from us, in the region of the constellation Cygnus. And it’s a particularly odd one. It was studied using the Kepler Space Observatory, which is the space telescope used for identifying planets orbiting distant stars. All of the exoplanet discoveries in the news over the past few years is due to Kepler.

To understand what’s odd about Tabby’s star, we need to know how Kepler operates. What it does is measure — very accurately — the apparent brightness of stars over time. If the apparent brightness of a star changes, that data is used to find patterns in how much and when the brightness changes occur.

Consider what happens with a planet revolving around a star. The apparent brightness of the star dips every time the planet passes in front — i.e. to observers here on Earth — of the star, and the amount and duration of the dip correlates with the size and velocity of the planet. This process works well, and has helped in the discovery of many, many exoplanets revolving around numerous star systems.

Now that we know the basics, here’s why Tabby’s star is so intriguing. Tabby’s star shows small dips in brightness that are both frequent and non-periodic. It has also shown two large recorded dips separated by two years time. How large are the large dips? Where a Jupiter sized planet would have obstructed the star by about 1%, the large dips obscure the star by as much as 15% to 22%. Whatever is blocking the star light during the major dips is not a planet — it is obscuring almost half the width of the star.

That’s not all. It turns out, even without the obscuring, the light output from Tabby’s star seems to be diminishing over time. It turns out, we have observational data about this star since 1890 (via numerous photographs that contain this star in the image), and it seems to have faded by 20% from 1890 to 1989! Even if such old and long-term data is deemed inaccurate, Tabby’s star has definitely diminished in the recent past, in the era of modern measurements. It seems to dim at a slow steady rate, with one short period of a more dramatic fading.

What could be causing such behavior? A number of hypotheses have been proposed, but none of them fully explain the observations. Could it be a young star with coalescing planetary material floating around it? Nope; no such evidence found. Could there be debris from planets that have collided and created clouds of debris and dust? Nope; this is not supported by observations. Could it be a huge number of disintegrating comets orbiting the star? Nope: they wouldn’t obscure the star’s luminosity by as much as 22%.

Well, could it be aliens?

We on Earth are starting to realize how important it is to harness the Sun’s energy as much as we can. We as a civilization have already fantasized about the creation of a huge structure that captures solar energy from every direction, not just from Earth, and using that energy as our planetary energy needs soar. Such a structure is a sphere that “covers” the Sun, and is called a Dyson Sphere, after the scientist who wrote a paper about it in 1960.

Dyson speculated that such a structure would become inevitable as a civilization advances and its energy needs escalate. Realistically, of course, the “sphere” wouldn’t be an actual sphere (imagine how big the sphere would have to be, and how it would revolve around the Sun!), but a “swarm” of smaller objects revolving around the Sun, like satellites. Collectively, they would serve a similar purpose.

What if the observations of Tabby’s star are the tell-tale signs of an alien civilization building a Dyson Swarm? It would explain the long-term fading, and also the sharp dips in its brightness. It would not be a planet; it’d be an artificial mega-structure being slowly constructed. Such construction projects could very easily — by design — obscure 22% of the star’s luminosity.

It’s an idea, and it’s a pretty fantasy for earthlings in the infancy of space-flight, but this idea does have its caveat. An advanced civilization would most likely have a lot of radio signal emissions (we do too — our TV and radio signals are propagating into space at the speed of light) that we should be able to detect. The SETI (Search for Extra-Terrestrial Intelligence) project spent two weeks studying the star system in October 2015, but did not find any technology-related radio signals in multiple frequency spectra.

If you can’t contain your excitement about the possibility of alien life, you still have hope. Whatever the caveat, and however slim the chances, scientists have not been able to rule out this possibility. More studies are planned that will devote resources — including that of SETI — towards studying Tabby’s star and its surroundings, and we will know more in 2017. If they’re really an advanced alien civilization, for all we know, they might have decided (and have the capability) to stop their radio signals from propagating into deep space!

If you’re apprehensive about finding aliens capable of — and in need of! — harnessing all of its star’s energy, you still have hope. What are the chances? For all the advancements we have made in astronomy and the study of the heavens, we really do yet have a lot to learn. When we observe anomalous behavior through our telescopes, the anomaly is due to limitations in our technology or understanding. What are the chances that this is the one case where our knowledge is perfect and the observations are unnatural?

Either way, this is one star we are certain to keep in our sights. The next few years will tell us more — about how little we know about the stars, or about how we’re not alone in the universe.

Updates:

  • This recent paper confirms that Tabby’s Star has faded throughout the duration of it being observed by Kepler. Other stars were also observed at the same time, and none of them fade at such a drastic rate. (doi:10.3847/2041-8205/830/2/L39)
  • The “Breakthrough Listen” project, backed by Prof. Stephen Fleming Hawking (oops, bad typo!) and funded by $100 million, will be used to observe Tabby’s star.

(This piece first appeared in the 2016 edition of Sharod Sombhar, an annual magazine from the Bengali Students’ Association at Virginia Tech.)


The Mystery of the Abydos flying machines in ancient Egypt

I had not heard of the Abydos carvings before. But then we went to Egypt, and it turned out that my Dad had requested that Abydos be put on the schedule—even though it wasn’t a ‘usual’ tourist destination. (I still don’t know whether he’d come across these specific carvings as a reason to go there. Baba, will you leave a comment if you read this? :))

But the carvings were quite amazing. There they were—a few of them adjacent to each other, each apparently depicting something we’d recognize as a modern (or future) means of air travel. (I have my own photos, but it’s easier to link to photos online.)

Was this really evidence that the Egyptians knew how to fly—or at the least, had witnessed flying machines?

My immediate thought was an emphatic NO. Not simply because it sounds implausible, and not because I don’t believe in aliens. Even if it is possible, I had my own reasons: amongst other qualities, the Egyptians certainly had one—they were record-keepers. They kept extremely intricate records of everything they knew about—and repeated this knowledge everywhere they could: every temple, every column, every tomb.

Is it really possible that they witnessed something so—forgive my pun—out of this world, and only made ONE reference to it? One set of carvings, in one temple, located in a far corner, high above the ground, where it is easily missed? Now that is implausible.

Of course I looked online when I was back—and initially, this is the best explanation that I found. Apparently a set of carvings were recarved, i.e. more carvings were done on top of the original—each modification at different times, even—with the end result being what we see today. I did not like this explanation at all. The webpage has some detailed drawings, but—I didn’t like it. How many separate coincidences must there have been—over many centuries of recarvings, done intentionally by different sets of people—that such an intriguing piece would result? Again, implausible.

Now I’ve found a better explanation. And this involves more chance and less human intervention. Apparently there are other carvings found at the same temple, which have nothing at all to do with avionics, that can explain our mystery. It can be something as simple as an incomplete carving, coupled with damage over the millennia!

Seen side by side, this image and this one seem to indicate quite convincingly that our mystery panel was meant to be similar to the other, more conventional, carving.

Granted, it’s still quite a coincidence—alien theorists, you need not retire yet on this one—but it still seems an acceptable coincidence!

Are you convinced, or are you looking up at the sky, trying to look past those cloaking devices?

P.S.: It’s so easy to find anything alien related on the internet! The cloaking device thing was intended as a joke, stemming in large part from my teenage—and, ahem, later—Animorphs days. I did a Google search looking for interesting links, and voila!