Thursday, February 4, 2016

Tabby's Star for the Perplexed

Last Update: 1 May 2016

Related Wow! Signal Podcast Audio Links:
Tabby's Star for the Perplexed, Part 1
Tabby's Star for Perplexed, Part 2
The Slow and Fast Dimming of Tabby's Star
DASCH Photometry with Josh Grindlay
Audio Interview with Tabetha Boyajian

When it comes to Tabby's Star (also known as KIC 8462852), we are all perplexed. This post is for those who are disinclined to read technical papers by professional astronomers, but would like to know just what the heck is going on. What is all this stuff about alien megastructures, swarms of giant comets, infrared excess, and old photographic plates? We'll lay all that out here for you in non-technical terms (or we'll explain the terms as we go). Please, if there are any questions, ask in the comments below, and we'll try and figure out an answer, if there is one. The post is richly hyperlinked, so if you want more detail, you can easily find it. I hope I have given credit wherever it is due.

Let me start by stating up front, that no one knows exactly what is going on with this star. What we'll try to lay out here is why this otherwise ordinary star is strange. If you have questions, or find errors, or know of updates I should include, please leave a comment here.

Thursday, January 14, 2016

Tabby's Star - Stay Tuned

I haven't written anything about Tabby's star (KIC 8462852) on here yet, although there was a discussion on the Unseen Podcast a few weeks ago. The latest is a preprint of a paper by Bradley Schaefer, in which he went in detail over the historical data for Tabby's Star and found a surprising result - the magnitude of the star has been steadily dimming over the time of the photographic record he use - the Harvard sky survey photographic plates, which date back to 1890. Depending on what you assume, the dimming is as fast as 0.2 magnitudes per century. Fast - a century is a blink of an eye in the life of a star, so this sort of rapid decline in brightness is not understood.

Anyway, interviewing Dr. Schaefer very soon, and you will all be able to hear what he says. I'll update this post when it's out. There is a bunch of other stuff to cover, like the initial SETI searches and the lack of IR excess.

Update: interview concluded, out soon. Subscribe to to get it when it comes out.

Here's the podcast blog page:

Wednesday, November 25, 2015

Why Interstellar Spaceflight is Hard

This was initially published in audio form as Burst 7 of the Wow! Signal. As part of the ongoing effort to tie this blog into that podcast and vice versa, we here present a slightly edited text version of the same.

This is a tutorial post, and is largely meant to bring some of our readers up to speed, since we are going to be talking about interstellar space flight more over the next months. If you have ever wondered by we can’t just get on a big rocket and fly to the stars, this is for you. If you already know why we can’t do that, then I think you might want to skip this one. 

Friday, November 20, 2015

4 Pi SETI - Why Not Build the Argus Radio Telescope Full Scale?

Robert Dixon
Update: we need to digest this first. All-sky there could be 2000 FRBs per day.

This  post - like nearly all the others - is about the questions I have. I am not a radio astronomer.I want to know how and how much and when about the radio telescope we will discuss below. This was stimulated by my interview with Robert Dixon last year, in which he discussed the virtues of the Argus concept. I lay awake that night thinking about it, and wondering why it hadn't been built yet.
The Search for Extraterrestrial Intelligence (aka SETI) is just that - a search. Like any search, it becomes much more difficult when more dimensions are added to the search space, and far easier when one or more of those dimensions are removed.

For example, if you are looking for an obscure little store with the best barbeque ribs in the West, and all you know is that it's in Los Angeles County, then your search space is quite large. However, if you have the additional information that it's on Santa Monica Boulevard, then you you still have some searching to do, but much, much less. You might even find the joint before it closes.

The problem with the SETI search is that it uses telescopes, and telescopes like the Allen Telescope Array or the Arecibo Observatory, only look at a small part of the sky at any one time. In fact, all the radio observatories in the world put together are only looking at a tiny sliver of the sky. If an ET beacon is transmitted for a short time while you are looking at another part of the sky (which you almost certainly are), you would completely miss it. We can dream about adding more telescopes to the search, but we would need a ridiculous number to cover the whole sky at once - or would we?

Tuesday, November 17, 2015

Questions about Asteroid Mining

What follows is based closely upon the Wow! Signal Podcast's Burst 8.

Lately, it’s been my sense that it’s time to spin up the asteroid mining conversation in earnest. Our most recent Unseen Podcast episode (#33) covered asteroid mining, and space policy expert James Muncy joined us for the first part of the show. We received a comment on the blog post for this episode by “Khani”, and here it is verbatim:

Question - (case 1) I travel to an asteroid of 100 meters in size. I start extracting materials from the "equatorial" zone. Is the material mine? (case 2) is the asteroid mine? (case 3) I move the asteroid, and now someone else lands on the other side and starts harvesting it. Is that "illegal" ? How much does the asteroid to be moved to be claimable? One meter?

Respectable test cases, I think, but we can go further.