Friday, January 21, 2011

The Sky is Falling?

The manufacturers of news have done it again. Thanks to CNN, Time,, and other gullible “news” purveyors, we learn that Betelgeuse, “the second biggest star in the Universe”, is going to explode “before 2012”, or, in more conservative moments, “in 2012”, placing a “second Sun” in Earth’s sky, turning day into night for several weeks. Further, according to these oracular media sources, we should not fear an apocalypse; rather, we will see Earth showered with “essential elements” such as “gold, silver, and uranium”, ostensibly made by a shower of neutrinos, for which we shall all be grateful. A promising mining opportunity!

This is a true blizzard of nonsense. Here are some facts than may relieve your minds:

The mass of Betelgeuse, though uncertain, is probably near 20 times the mass of the Sun. If it is that massive, it will eventually explode (if it is less than 9 times the mass of the Sun it will not explode).

Betelgeuse is not the “second biggest star in the Universe”. It is the second brightest star in the constellation of Orion. If we generously allow that it may be the “second biggest star in the Galaxy”, then it would be something like the ten billionth biggest star in the Universe.

The actual expected remaining lifetime of Betelgeuse is at least a million years, and possibly several million. The probability that Betelgeuse will explode in 2011 (or 2012) is about 0.000001.

If Betelgeuse explodes the first we will know of the event is the arrival of the light given off by the explosion, closely followed by a blast of neutrinos.

The supernova explosion will shine with the brightness of about 100 million Suns. At Betelgeuse’s distance (about 40 million AU), its flash will provide less than 1/100,000,000 of the intensity of Sunlight on Earth for about two weeks. It may be faintly visible in the daytime sky, and surely will be no more spectacular than the full Moon.

If Betelgeuse explodes it will shower Earth with neutrinos, which will have no significant effect on Earth. The neutrinos will not make “useful elements”: they generally pass through Earth as if it weren’t there.

The gases ejected from the explosion of Betelgeuse will form an expanding shell of relativistic gas traveling at about 5% of the speed of light. The first arrival of these gases at Earth will occur about 12,000 years after the initial flash of the explosion.

The gases striking Earth would amount to about 300 grams per square kilometer over a period of several years. Assuming that about half the incoming mass is gases such as hydrogen and helium and half is heavy elements, Earth would collect a dust layer about 0.000000005 cm thick.

If you want to take advantage of the availability of the freshly synthesized uranium, in the dust, the uranium content will be equivalent to a layer 0.0000000000000001 cm thick on average (that’s less than 1/1000th of the diameter of an atom!) Good luck with the mining!

If that doesn’t entertain you, then perhaps this will : these articles reinforce their apocalyptic message by drawing a parallel with the “predictions” of the Mayan Calendar that “Armageddon” will occur in 2012. Really? The end of the world AGAIN? And what precisely is the Mayan word for “Armageddon”?

This nonsense becomes “news” because some reporters are too lazy to check out the facts with knowledgeable sources, and completely ignorant of the use of numbers.

No, Chicken Little, the sky is not falling.

Tuesday, January 18, 2011

Astrology on CNN

Yesterday I watched an interview with an astrologer on a network that purports to deliver news. For wholly incomprehensible reasons, the interviewer chose to ask an astrologer about NASA’s designation of a “new constellation of the Zodiac”. Actually, the designation of the boundaries of constellations is the work of a committee charged with nomenclatural issues, and has no physical significance. Decades ago the sprawling constellation Serpens (the Serpent) was subdivided for purely practical reasons into Serpens Caput (the Serpent’s Head), Ophiuchus (the Serpent Handler) and Serpens Cauda (the Serpent’s Tail). Incredibly, the interview dwelt on the entirely specious issue of whether this changed people’s horoscopes, not with the actual story. Both the interviewee and interviewer demonstrated their level of understanding by admitting that they couldn’t even pronounce Ophiuchus.

Here’s my slant on the subject. Astrology purports that the positions of the planets against the background of “fixed” stars exerts a significant influence on people. Astronomers purport that the positions of the planets reflect precise quantitative laws. For planet-sized bodies, gravitation is by far the dominating effect. Both systems claim to have predictive and descriptive power.

Thus use of the Law of Universal Gravitation in its relativistic formulation permits extremely precise calculations of the paths of the planets through the sky, so precise that encounters of spacecraft with other planets can be planned and predicted with a precision on the order of one second after years of flight. Astronomers, using the laws of gravitation and precise observations, can detect tiny perturbations of the orbits of known planets by unknown planets (or, in the case of planetary systems of other stars, of visible stars by their unseen planets) and deduce the presence of these previously unknown bodies. Uranus was discovered by accident as a result of systematic observations by astronomers. Neptune, Pluto, and several hundred planets of other stars have been discovered by means of calculated disturbances of the orbits of nearby bodies.

Now, if the positions of the planets have influences on human affairs, periodic patterns must be present in human events. Astrology, by the simple means of identifying cyclic patters in human events, should be able to determine the existence, synodic period, and influence of hitherto unknown planets. But any such behavioral perturbations remained unnoticed. Astrology was completely ignorant of the existence of Uranus until it was discovered by astronomers. They remained completely ignorant of the existence of Neptune until it was discovered by astronomers because of its gravitational effects on Uranus, and were similarly ignorant of the very existence of Pluto until an astronomer discovered it. Astrologers can make no claims about planets of other stars, but astronomers can point to over 500 discoveries of exoplanets.

If the human influences of the planets are important, how is it that not a single planet has ever been predicted or discovered by astrologers? Clearly, astrology has no predictive power.

Thursday, January 13, 2011

Amateurs in Astronomy

There are few sciences in which amateurs still play a major role. Astronomy, despite its obvious heavy reliance on giant and very expensive telescopes and observing instruments, is perhaps the most fruitful field for amateur involvement. How is this possible?

Consider the situation: a few hundred professional astronomers in the United States generate data at a rate that exceeds their own ability to analyze it. Further, the fields of view of most large telescopes are so small that only a tiny fraction of the sky is under observation at any given moment. At the same time, the explosive growth of electronics technology have made it possible for many thousands of amateurs to buy equipment that rivals in sensitivity the best professional equipment of a few years ago. This combination of circumstances has empowered amateur astronomers as never before.

Indeed, on-line data repositories have enabled “astronomers without telescopes” to make valuable contributions on a daily basis by means of “data mining” in these vast archives.

Here are a few of the ways that amateurs make valuable, even essential, contribution:

1. Variable star observations. Many stars are variables with periodic changes in brightness. Thanks to decades of diligent work, largely coordinated by the American Association of Variable Star Observers (AAVSO), high-quality observations of the variation of brightness with time (what astronomers call a “light curve”) of many thousands of stars can be collected by observers with small telescopes and be made available to professional observers and theorists free of charge.

2. Meteor observations. Virtually all meteor observations are conducted by amateurs. The American Meteor Society (AMS) advises and coordinates observation programs that provide most of our knowledge about meteor swarms, showers, and storms. They provide essential data for constructing and testing orbital evolution models for natural space debris and for predicting future observational opportunities.

3. Comet seeking. Most astronomical comet discoveries have traditionally been made by nighttime observations by amateur astronomers using small to medium-sized telescopes.

4. Asteroid and comet orbit followup. Several major sky-survey programs have been established in recent years for the purpose of discovering near-Earth objects, especially near-Earth asteroids (NEAs) and short-period comets, which present an impact hazard on Earth. These programs include the Lowell Observatory Near-Earth Asteroid Search (LONEOS), Spacewatch and the Catalina Sky Survey of the University of Arizona, the Lincoln Near-Earth Asteroid Research program (LINEAR), the Jet Propulsion Laboratory’s Near-Earth Asteroid Tracking (NEAT) , and several other smaller programs. The discovery of small, faint, fast-moving nearby asteroids requires relatively large and expensive equipment. However, once discovered, much smaller telescopes can be enlisted to do the follow-up work needed to calculate a precise and reliable orbit. Amateurs are heavily involved in this work.

5. Sun-grazing comet discovery. Data-mining in the on-line database of images of the Sun produced by the Solar and Heliospheric Observatory (SOHO) satellite have made it possible for amateurs without telescopes to discover hundreds of Sun-grazing comets.

6. Data mining in the Sloan Digital Sky Survey (SDSS). SDSS has been successfully mined to discover hundreds of distant supernovas, thousands of main-belt and near-Earth asteroids, and hundreds of comets. There have been two major releases of many terabytes of sky-image data (SDSS-I and SDSS-II) to the public domain.

7. Data mining in the Hubble Space Telescope (HST) archives. Recently a supernova was discovered in the HST archives by a 12-year-old girl.

You could make a valuable contribution to astronomy! Amateur astronomers, regardless of whether they own a telescope, can find out more about these opportunities through online searches of the programs listed above. All provide the ability to participate in cutting-edge research programs and contribute to human knowledge.

"Demandite" and Resources in Space

“Demandite” is the word used by mineral economists to describe the materials that must be provided-- usually by mining-- to meet the needs of civilization. In the usual terrestrial setting, air and water are assumed to be freely available, and fossil fuel (natural gas, crude oil, and coal) is considered a necessity. In space, where dependence on solar energy is the norm, and where air and water must be “mined”, the numbers are different. The proportions of mineral needs, however, are otherwise generally similar. You can then ask how much of each material (iron, carbon, nitrogen, aluminum, copper, oxygen, water, nitrogen, etc.) is needed to be in circulation to support one person, depending on “renewable” (inexhaustible) solar energy to drive industry, agriculture, and recycling. We can then compare those requirements to the natural resources available on bodies in nearby space, and calculate how many people could be supported at each of those locations.

The proportions of these necessary materials (the relative abundances of water and iron, for example) are very different on the Moon, Mars, and nearby asteroids. The Moon, for example, is severely deficient in all volatile elements, including carbon, nitrogen, hydrogen, and chlorine, Mars, with its tenuous atmosphere and widespread ice deposits, fares better. But best by far is the match between the composition of near-Earth asteroids (NEAs) and “space-based demandite”. The 1000 or so kilometer-sized near-Earth asteroids contain enough of every essential element to support a population of 10 billion people from now until the Sun dies of old age. The NEAs, however, are a renewable resource: in nature, the rate at which NEAs are lost by collision with planets and ejection from the Solar System is compensated by recruitment of fresh asteroids kicked into near-Earth space by Jupiter’s gravitational interactions.

But what about the main Asteroid Belt? The answer is startling: the Belt contains one million times as much mass as the entire NEA population. Again depending on the Sun for power, the Belt could support a population of 10 million billion people-- a million times the ultimate carrying capacity of Earth. With that many people, wouldn’t we be running out of solar power? Not really-- even under these extreme assumptions, we would require less than one millionth of the Sun’s output energy.

The non-renewable resources available to Earth-bound humanity are finite. The resources available to a space-faring humanity are effectively infinite.