Tabby’s Megastructure Mystery

February 20, 2017

So I’ve flown my spaceship all the way out to KIC 8462852, better known as Tabby’s Star, and what do you know? The aliens really are building a megastructure out here.

fb20-tabbys-star

This whole situation is pretty weird, I know; but the weirdest thing is that when I check my ship’s sensors, I can’t detect any thermal emissions from the megastructure or any of the spaceships involved in constructing it.

The lack of thermal emissions (or the lack of an “infrared excess,” as the experts call it) is one of the main reasons why Tabetha Boyajian and other legitimate scientists don’t really buy the alien megastructure hypothosis.

Think about it. If Tabby’s Star hosts an active work zone, with spaceships flying around and construction workers welding space girders and stuff, you’d expect all that activity to produce some heat. Even without the construction activity, the megastructure itself should be pretty warm due to the star it encircles.

And all that heat should be detectable in the form of infrared radiation. But whether you observe Tabby’s Star with a telescope back on Earth or the sensor grid of my imaginary spaceship, the total amount of infrared light is exactly what you’d expect from an F-type main-sequence star. No more, no less.

Since I’m here, I decided to ask one of the alien construction workers about this. Here’s what he told me: “Yeah, we been masking our thermal emissions. What of it? We don’ts wants nobody snooping in our business. Now scram, smelly human!”

Not exactly the answer I was expecting, but I guess I’ll take what I can get.

P.S.: If you want to learn more about Tabby’s Star and how citizen science helped uncover its mysterious behavior, I strongly recommend this SciShow interview with Tabetha Boyajian. That’s where I first learned about the “infrared excess” issue that I discussed in today’s post.


Sciency Words: Tabby’s Star

February 17, 2017

Sciency Words PHYS copy

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

TABBY’S STAR

Something’s wrong with a star named KIC 8462852. It flickers. It dims by as much as 22% for no apparent reason. This is an F-type main-sequence star, meaning it’s only a little bit larger than our Sun. F-type stars shouldn’t behave like this.

KIC 8462852 is sometimes called the WTF Star, because of the paper that first described its abnormal fluctuations in brightness. That paper was subtitled “Where’s the Flux?”

The star is also known (and perhaps better known) as Tabby’s Star, in honor of Tabetha Boyajian, the lead author on that paper.

There are several possible explanations for what might be happening to Tabby’s Star, but it’s the least likely explanation that’s gotten the most hype. Could it be aliens? SETI decided to check it out. They didn’t find anything. But still… it could be aliens.

Massive alien starships might be transiting the star, blocking some of its light. Or perhaps there are enormous space stations orbiting the star. Or maybe we’ve caught an advanced alien civilization in the act of building some kind of megastructure (like a Dyson sphere) completely encircling their sun.

Most professional astronomers do not think it’s aliens. Tabetha Boyajian herself doesn’t seem to take the idea seriously and often jokes about the crazy emails she gets from people who do. And to be perfectly clear, I do not take this alien megastructure hypothesis seriously either.

But just to be sure, I’ve decided to hop into my imaginary spaceship and fly out to KIC 8462852, just so I can see for myself what’s really going on. Wish me luck! I’ll let you know what I find next week.

fb17-approaching-tabbys-star


Planet Pailly: The Movie Trailer

February 9, 2017

Please read this in your best movie trailer voice:

* * *

In a world where science fiction writers often forget about science, one man wanted to do his research.

fb08-blog-trailer-1

And one muse told him he should totally do that.

fb08-blog-trailer-2

Coming February 15, 2017, these two will set out in their imaginary spaceship, continuing their voyages through the Solar System and beyond, and learning as much about science as their tiny brains can hold.

fb08-blog-trailer-3

Coming soon to an internet near you. This blog not yet rated by the MPAA.


Life on Mars: The Hunt for Martian Dinosaurs

December 28, 2016

Can Mars support life? Is there anything living on Mars right now? It sometimes seems like Mars is desperately trying to convince us that the answer to both questions is yes.

dc28-life-on-mars

If you’re hunting for alien life in the Solar System, there are four places you should pay attention to: Mars, Europa, Enceladus, and Titan. Now a thought recently occurred to me—a thought that I’m sure has occurred to other people before: in an astrobiological sense, these four worlds sort of represent the past, present, and future.

  • Mars: a place where alien life might have existed and thrived in the past.
  • Europa and Enceladus: places where life may exist and thrive in the present.
  • Titan: a place where life might start to evolve and thrive sometime in the future (assuming it hasn’t started already).

Regarding Mars, there was clearly a time when rivers, lakes, and oceans of liquid water covered the Martian surface. There’s growing evidence that at least some of the organic chemicals necessary for life were also present. Therefore it’s easy to imagine a time millions or perhaps billions of years ago when Mars had a biosphere as rich and robust as prehistoric Earth’s.

Obviously that robust biosphere is gone now. Even when we hear about the possibility that life still exists on present-day Mars, it’s generally assumed that this life would be only a remnant of what came before. The microbial survivors of whatever wiped out the Martian dinosaurs, so to speak.

Someday (hopefully soon), humans will travel to Mars. When we get there, we may find that all the Martians are long dead. That might seem a bit depressing, but actually I’m kind of excited by the idea that the fossilized remains of Martian dinosaurs might be there, waiting for us to come dig them up.


Sciency Words: Frost Line

December 23, 2016

Welcome to a very special holiday edition of Sciency Words! Today’s science or science-related term is:

FROST LINE

When a new star is forming, it’s typically surrounded by a swirling cloud of dust and gas called an accretion disk. Heat radiating from the baby star plus heat trapped in the disk itself vaporizes water and other volatile chemicals, which are then swept off into space by the solar wind.

But as you move farther away from the star, the temperature of the accretion disk tends to drop. Eventually, you reach a point where it’s cold enough for water to remain in its solid ice form. This is known as the frost line (or snow line, or ice line, or frost boundary).

Of course not all volatiles freeze or vaporize at the same temperature. When necessary, science writers will specify which frost line (or lines) they’re talking about. For example, a distinction might be made between the water frost line versus the nitrogen frost line versus the methane frost line, etc. But in general, if you see the term frost line by itself without any specifiers, I think you can safely assume it’s the water frost line.

Even though our Sun’s accretion disk is long gone, the frost line still loosely marks the boundary between the warmth of the inner Solar System and the coldness of the outer Solar System. The line is smack-dab in the middle of the asteroid belt, and it’s been observed that main belt asteroids tend to be rockier or icier depending on which side of the line they’re on.

It was easier for giant planets like Jupiter and Saturn to form beyond the frost line, since they had so much more solid matter to work with. And icy objects like Europa, Titan, and Pluto—places so cold that water is basically a kind of rock—only exist as they do because they formed beyond the frost line. This has led to the old saying:

dc23-outer-solar-system-christmas-party

Okay, maybe that’s not an old saying, but I really wanted this to be a holiday-themed post.


What’s Up with Juno?

December 20, 2016

It’s been awhile since we checked in with Juno, the NASA space probe currently orbiting Jupiter. So Juno, how’s the mission going?

dc20-juno-update-1

Uh-oh. That doesn’t sound good. What happened?

dc20-juno-update-2

Okay, here’s a quick timeline of events:

  • On July 4, 2016, Juno entered orbit of Jupiter. The main engine worked flawlessly at the time.
  • On August 27, 2016, Juno performed its first science pass of Jupiter. All its instruments appeared to be in working order.
  • On October 19, 2016, Juno was supposed to shorten its orbital period from 53 days to 14 days, but there was a problem with the main engine. Plan B was to just do another science pass, but then there was a problem with the main computer.

According to this article from Spaceflight 101, we now know what happened with the computer, and it sounds like it’ll be a fairly easy fix. The malfunction was caused by an instrument called JIRAM. Continuing with our timeline:

  • On December 11, 2016, Juno performed another science pass, this time with JIRAM switched off. All the other science instruments seem to be in working order, and a software patch for JIRAM will be uploaded soon.
  • Coming February 2, 2017, Juno will approach Jupiter again. This will likely be another science pass, since NASA still doesn’t know what’s wrong with the main engine.

The main engine is turning out to be the real problem. According to a press release from October, some pressure valves that should have opened in a matter of seconds took several minutes to open. Until NASA figures out why that’s happening, they’re going to leave Juno’s orbit alone.

Juno can still perform its mission in its current 53-day orbit; it’ll just take longer. We’re looking at five years rather than the original year-and-a-half. That screws up the original science observation calendar, and the prolonged exposure to Jupiter’s intense magnetic field might lead to more computer glitches in the future.

dc20-juno-update-3

Fingers crossed.


Sciency Words: The Zero-One-Infinity Rule

December 16, 2016

Sciency Words MATH

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

THE ZERO-ONE-INFINITY RULE

I came across this term in Time’s special edition on Scott Kelly’s year in space, which I reviewed on Wednesday. The term was used in an article about astrobiology, but it actually originates in the field of computer science.

Zero-One-Infinity in Computer Science

The zero-one-infinity rule is sort of a rule of thumb. It’s credited to Dutch computer scientist Willem Louis Van Der Poel. According to this rule, a computer program should either never allow a certain event (zero), or it should allow it only once (one), or it should allow it an unlimited number of times (infinity).

The logic here is that it makes sense to not allow something to happen. It also might make sense to allow something to happen only once, perhaps as an exception. But programmers shouldn’t create arbitrary limits (according to this rule) on what a program can do. If you’re willing to allow something to happen twice, why not three times? Or four? Or thirty-eight? Or as many times as the user wants (computer memory space permitting)?

I don’t have a whole lot of coding experience, but the zero-one-infinity rule makes sense to me. It seems like a good rule, although I could probably think up more than one exception to the rule if I really wanted to.

Zero-One-Infinity in Astrobiology

Applying the zero-one-infinity rule to the search for alien life is, in my opinion, brilliant. How many locations in the universe can support life? There are really only three answers:

  • Life cannot exist anywhere in the universe (zero).
  • Life can exist only on Earth; Earth is a very special exception in a universe where life is otherwise not allowed (one).
  • Life can exist in an unlimited number of locations in the universe (infinity).

We already know the zero proposition is false.

There was a time (I remember it well) when many a scientist argued that Earth must be an exception: the one and only place in the universe where life could exist. Occasionally, I still hear people try to argue this.

All it would take is to find a second life-bearing world to prove the one proposition wrong (I’m looking at you, Europa). Because once we know about two living worlds, how could anyone argue that there can’t be three? Or four? Or thirty-eight? Or however many the universe feels like having?

Links

Zero-One-Infinity Rule from The Jargon File.

Willem Louis Van Der Poel from Wiki Wiki Web.