Saturday, November 30, 2013

"What was that bright light in the sky last night?"

While looking for information on comet ISON, I ran across an interesting project by NASA: the All Sky Fireball Network, a network of (currently) 12 black-and-white video cameras able to image the whole night sky.  The images from these cameras are processed by ASGARD (All Sky and Guided Automatic Realtime Detection), developed for a similar effort in Canada.  These astro folks sure love their acronyms.

A "fireball" is any meteor brighter than venus.  These are not rare events.  There are several on most nights, and nights with a dozen or two are not uncommon.   As there is deliberately quite a bit of overlap in the cameras' fields of view, most fireballs are caught on multiple cameras, making it possible to calculate the three-dimensional trajectory of the meteor, and from that determine its orbit. posts a graphic of the night's calculated orbits.  I believe they produce that themselves from the raw data on the NASA site, which just seems to show the orbital elements as text.

It's pretty easy to see why this data is of interest to NASA.  Not only does it provide information about the composition of the Solar System, it's of practical use in designing satellites.  But even without that, it's a just plain neat hack.

Wednesday, November 20, 2013

Straight dope on Comet ISON

In a few days, a highly unusual comet will pass within a million miles or so of the Sun's surface.  That in itself is not unusual.   Comets pass that closely reasonably often and thousands such are known.  However, this comet is a "dynamically new" comet, meaning it has never been close to the Sun before, and no dynamically new comet has come so close to the Sun in at least 200 years.

This rare combination offers an unprecedented chance for astronomers to observe an object which has basically been sitting in a deep freeze since the formation of the Solar System react to close contact with the heat of the Sun.  That in turn will reveal much about what the comet is made of and thus offer clues about how the Solar System itself was formed.  Dozens of major observatories, on Earth and in space, will be watching.

As I write, the comet is visible to the naked eye in the pre-dawn sky, but only if you're in a dark place and know just where to look.  It's a little point of light, not your classic image of a comet.  At least not yet.

While ISON's orbit is known quite precisely, it's not at all clear what happens next.  On November 28th it will reach perihelion, its closest point to the Sun's center.  It will be moving at about 400 km/s, or about 900,000 mph, and experiencing intense heat and significant tidal stress that may or may not destroy it.  If it survives, it may reappear as anything from a point of light to a real spectacle.

If you've seen reports of a "comet of the century" likely to be "brighter than the full moon", this would be it.  The press has a habit of taking the "this could maybe happen if we're really lucky" scenario and running with it.  If you prefer to know what actual astronomers are saying and seeing and what the comet is up to, along with informative discussions of why we don't really know what the comet will do, you'll want to check out CIOC, NASA's Comet ISON Observing Campaign.

CIOC is a coordinating group.  It's not performing the actual observations, but it is a serious scientific collaboration, promoting research and gathering results for all the to see.  This is classic Web, the kind of thing TimBL had in mind, I have to think, when putting up the first HTTP server way back when.

You may be wondering: What kind of a name is Comet ISON anyway?  It's named after the International Scientific Optical Network, a collection of 30 or so telescopes in about 20 countries that has been used in quite a bit of research, including but definitely not limited to detecting the comet in the subject line, formally known as C/2012 S1 (ISON).

UPDATE: Comet ISON appeared to disintegrate just before perihelion, and when it dropped behind the occluding discs of the SOHO (SOlar and Heliospheric Observatory) cameras that have been the main source of images for it in the past few days, the consensus was that there was a good chance that nothing would come out the other side.  When the SDO (Solar Dynamics Observatory) and PROBA (PRoject for On Board Autonomy) scopes that had been pointed at what should have been ISON's path failed to detect anything, the folks at CIOC did the only reasonable thing and declared it dead, vaporized in the heat of the sun (around 2800℃/5000℉).  And then it re-appeared.  At this writing, it is a fuzzy blob headed away from the sun, nowhere near as bright as it had been, but possibly bright enough to be seen with the naked eye when it gets far enough away from the sun.  We shall see.

UPDATE:  ... and it's gone.  On December 18th, the Hubble telescope was pointed at where Comet ISON ought to have been.  We can be quite sure of the location since anything solid remaining would have continued to follow the original orbit -- a solid object moving that fast is not going to be affected significantly by outgassing, the solar wind or other such effects.  The HubbleSite ISON blog has the full details, including photographs annotated to point out things you might think could be comet remains but definitely aren't.  Cosmic rays, stars streaking because the telescope is moving to follow the orbit of the comet, reflections on the lens and so forth.  Plenty of that, no comet.

Two ways to value Bitcoin

I really should find something to write about besides Bitcoin, but while I'm figuring that out …

Timothy B. Lee of the Washington Post has an interesting take on Bitcoin (now trading around $370 as I write this, off its all-time high of $395 -- and now more like $325 as I proofread), modestly entitled Everything you need to know about the Bitcoin "Bubble".  The gist appears to be, "No, Bitcoin is not and will never be a reserve currency, but that doesn't matter.  It can still be intrinsically worth something."

The basis of this is an analogy with the internet.  Like Bitcoin, the internet was once the province of cutting-edge technophiles and other such.  Like the early internet, Bitcoin has a few adventurous players trying to build commercial applications on it.  And, Lee argues, like the early internet, Bitcoin is an open platform.  Specifically, Bitcoin is a payments platform, and companies like Bitpay and Coinbase are working to build payment applications on top of that.

Because Bitcoin isn't really acting as a currency -- but rather, businesses using Bitcoin price in other currencies and convert back and forth to Bitcoin -- the usual arguments against Bitcoin as a currency don't really matter.  The deflationary aspect of a fixed money supply doesn't matter because no one's savings or salary are denominated in Bitcoin.

The price volatility doesn't matter greatly because Bitcoin transactions are ephemeral.  As the payments systems become more mature, the amount of time between the money -> Bitcoin transaction and the Bitcoin -> money transaction should become shorter, and if volume is decent, there are ways of netting out most transactions and minimizing one's exposure to swings in the price.

That's fine, but it says little or nothing about what the actual price of Bitcoin should be.  As long as there are enough Bitcoin in circulation, keeping in mind that there is good incentive for parties using Bitcoin in payment to minimize the amount they keep on hand, it hardly matters whether a Bitcoin is worth $1 million or a penny.  This makes me particularly skeptical about Lee's assertion that "[I]f Bitcoin becomes an important part of the global financial system, its value would need to go a lot higher to accommodate the millions or billions of Bitcoin-based transactions that might occur in the future."

The current dollar value of all Bitcoin is around $325 * 12 million, or just under $4 billion.  By comparison, MasterCard moves about $1 trillion per year, or around $3 billion per day.  Since the same Bitcoin can be re-used over and over again in different transactions, it seems very likely we have well more than enough dollars worth of Bitcoin in circulation right now to last for a very long time, even assuming it becomes a major factor ["same Bitcoin" is not quite accurate, but I believe the point still holds -- we care about the maximum amount in a payment handler's account, and that will deliberately be kept low].  By comparison the current background level of Bitcoin trading, when it's not in a speculative froth, is a small number of millions of dollars.

In any case, how much is a platform worth?  If the analogy is to the internet and the web, how much is HTTP worth?  I'd argue it doesn't have a value, per se.  People make money writing applications that use it, and producing better implementations of it and other protocols, by providing bandwidth for it to run on and so forth, but you can't buy or sell HTTP.  Even if it were patented -- in which case it would almost certainly not be the universal standard it is today -- the value of the patent would only be indirectly related to the value of the business being done on it.

Likewise, just as you can put a value on a company like Bitpay or Coinbase, by looking at how much actual money they bring in, you can't really put a value on Bitcoin as a platform.

Which brings us back to the same two ways to value Bitcoin:
  • How much dollar value needs to be in circulation for it to work as a payments platform -- something
  • How much speculators are willing to pay for it -- a lot
It's not that Bitcoin can't have intrinsic value.  It does, just not very much compared to its current speculative value.  Who knows what that value will be tomorrow, or a year from now?  Could be in the thousands, could be next to nothing.