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Following up on Another Earth?
That “Goldilocks” Exoplanet May Not Exist
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Tag Archives: astronomy
Tiny rock to buzz Earth Tuesday
Frozen dwarf planets
Frozen World of Eris Looks a Lot Like Pluto
The frozen surface of the dwarf planet Eris looks a lot like that of its smaller neighbor Pluto, new research has found.
Both frozen worlds are covered predominantly with nitrogen ice, a research team announced Tuesday (Oct. 5). The find could help astronomers get a better handle on the history of the outer reaches of the solar system….
Eris, discovered in 2005 by planet-hunting astronomer Michael Brown, has one known moon called Dysnomia.
Eris is larger than Pluto — about 1,600 miles (2,581 kilometers) across, compared with 1,430 miles (2,306 km) — and about 27 percent more massive. Eris’ bulk effectively forced astronomers to strip Pluto of its planethood and rebrand it a “dwarf planet” back in 2006.
The ensuing controversy over Pluto’s demotion makes Eris’ name quite fitting: Eris is the Greek goddess of discord and strife, who stirred up jealousy and envy among the goddesses, leading to the Trojan War.
Eris circles the sun from about 9 billion miles (15 billion km) away, making it about twice as remote as Pluto.
Searching for Extraterrestrial AI
Looking for E.T.? Try His Artificial Intelligence Instead, Astronomer Says
The suggestion that artificial ET’s might more evident than biological ones is not new. Frank Tipler (before he went off the deep end) suggested in 1981 that alien civilizations might use von Neumann probes to explore a galaxy. He concluded that since we do not see such probes,
there are no ET’s in our galaxy. In science fiction the concept goes back at least to 1963, when Fred Saberhagen’s first Berserker story appeared.
Actually, almost all suggestion for SETI come down to Searches for ExtraTerrestial Technology. It will be a long time before we can find any other sign of intelligence out there.
Bok globules are another search target for sentient machines. These dense regions of dust and gas are notorious for producing multiple-star systems. At around negative 441 degrees Fahrenheit, they are about 160 degrees F colder than most of interstellar space. [Is this correct?-GTM]
This climate could be a major draw because thermodynamics implies that machinery will be more efficient in cool regions that can function as a large “heat sink”. A Bok globule’s super-cooled environment might represent the Goldilocks Zone for the machines, says Shostak.
The idea that Bok Globules might be linked to ET’s was anticipated by Fred Hoyle in his 1957 novel The Black Cloud. Early in the book some astronomers are looking at some images of the cloud (which turns out to be an intelligent and powerful life form). One of them describes it as “a fine example of a Bok globule.”
Back at work after 36 years
Lost Rover Found on Moon With Retroreflector Still Intact.
The rediscovery of the reflector could have an important impact in several areas of science that depend on accurately measuring the position and orbit of the Moon. Laser rangefinding currently provides the most precise tests of many aspects of gravity, including the strong equivalence principle, the constancy of Newton’s constant, geodetic precession, gravitomagnetism and the inverse square law.
Technical details at Laser Ranging to the Lost Lunokhod~1 Reflector.
Another Earth?
Newly discovered planet may be first truly habitable exoplanet
A team of planet hunters led by astronomers at the University of California, Santa Cruz, and the Carnegie Institution of Washington has announced the discovery of an Earth-sized planet (three times the mass of Earth) orbiting a nearby star at a distance that places it squarely in the middle of the star’s “habitable zone,” where liquid water could exist on the planet’s surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.
Via Possible earthlike planet found in the Goldilocks zone of a nearby star! which includes some cautions, beginning with:
However, this does not mean the planet is habitable, or even very Earthlike. It may not even have any water on it at all. For now, we can’t know these things, so beware of any media breathlessly talking about life on this planet, or how we could live there.
A scientist at the Vatican
Brother Astronomer: Adventures of a Vatican Scientist
Brother Guy Consolmagno, S.J., is a Planetary Scientist, specializing in meteorites, and a Jesuit brother. He writes about the different types of meteorites and their significance in the first section. The second section is about the church, where he argues that the trial of Galileo was a tragic aberration, and discusses the theological justification for science in the works of St. Athanasius and of John Scotus Eriugena. Later chapters include some autobiography, a discussion of aliens and their possible theological implications (short answer: no problem), and a concluding section about exploring for meteorites in Antarctica.
He has a first rate education in both science and religion, and is obviously very comfortable with both and sees no problem reconciling them. Neither do his Jesuit superiors.
I have read quite a bit on science and religion, but mostly from a somewhat detached academic point of view. Brother Astronomer is a very refreshing view from the inside. Brother Guy is perfectly aware of all the historical, religious, and scientific background, but communicating that is not his purpose. He is a working scientist. His scientific work is his Christian vocation. That is what he trying to communicate, and he does it very well.
Brother Guy was recently interviewed by some of the British news media, resulting in stories such as:
- Pope Benedict XVI’s astronomer: the Catholic Church welcomes aliens
- Pope’s astronomer says he would baptise an alien if it asked him
His comments on all of this are at Anybody want my last three minutes of fame? .
Crackpot of the week!
A Laser Strike at the Galactic Center
Great picture at APOD
Why are these people shooting a powerful laser into the center of our Galaxy?
Phil Plait explains:
The laser shoots up into the sky and excites atoms in the upper atmosphere, causing them to glow. That makes an artificial and very bright star in the sky! The telescope can then use that star to track the distortions in the atmosphere and compensate for them, allowing the images it makes to be incredibly clear and sharp.
With the laser, modern computers, and adaptive optics astronomers have solved a problem with Earth-based optical telescopes that goes back to Galileo.
Note that this is a technique for visible light observations. Space-based observatories are needed for the parts of the electromagnetic spectrum that are blocked by the Earth’s atmosphere.
Solar Flares and Radioactive Decay
From Stanford University News and Symmetry Magazine (The latter has a small but important correction—See the 1st comment and the response)
It’s a mystery that presented itself unexpectedly: The radioactive decay of some elements sitting quietly in laboratories on Earth seemed to be influenced by activities inside the sun, 93 million miles away.
Is this possible?
Researchers from Stanford and Purdue universities believe it is. But their explanation of how it happens opens the door to yet another mystery.
Also discussed by Jeff Duntemann.
The article mentioned the decays Silicon-32 and Radium-226, as reported in Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance back in 2008. Similarly, Perturbation of Nuclear Decay Rates During the Solar Flare of 13 December 2006 indicated a solar dependence on the decay of Manganese-54. The suggestion that radioactive decay rates might in some way depend on the sun is quite extraordinary, and has prompted the reanalysis of a lot of data. Evidence against correlations between nuclear decay rates and Earth-Sun distance looked at the decay of 6 other radioisotopes without seeing any such dependence. There is no obvious dependence on atomic weight or other systematic difference between the elements.
There are different types of radioactive decay. Radium-226 decays by emitting an α particle (a Helium nucleus: 2 protons and 2 neutrons) while Silicon-32 is a case of β decay (emission of an electron). Manganese-54 decays by electron capture, which is essentially time-reversed β decay. α-decay is a manifestation of the of the strong nuclear force, while β-decay is a weak interaction. If the solar effect is real, then affects two differenct fundamental forces of nature.
John G. Cramer, in Radioactive Decay and the Earth-Sun Distance suggested that
…the Earth’s orbit has a very small eccentricity, so the annual variations in R [the Earth-Sun distance] are small. A better way of testing whether radioactive decay rates depend directly on 1/R2 would be to monitor a radioactive decay process within a space vehicle in a long elliptic orbit with a large eccentricity, so that R has a very large variation. As it happens, NASA has a number of space probes that match this description, because many space probes, particularly those that venture into the outer reaches of the Solar System, are powered by radioisotope-driven thermoelectric power sources containing a strong radioactive decay source that produces enough energy as heat to power the vehicle. The power levels of such thermoelectric generators are carefully monitored because they constitute the principal power source of the vehicle.
This has been done. According to Peter Cooper, in Searching for modifications to the exponential radioactive decay law with the Cassini spacecraft
Data from the power output of the radioisotope thermoelectric generators aboard the Cassini spacecraft are used to test the conjecture that small deviations observed in terrestrial measurements of the exponential radioactive decay law are correlated with the Earth-Sun distance. No significant deviations from exponential decay are observed over a range of 0.7 – 1.6 A.U. A 90% Cl upper limit of 0.84 x 10-4 is set on a term in the decay rate of Pu-238 proportional to 1/R2 and 0.99 x 10-4 for a term proportional to 1/R.
Deep-space probes usually generate power from the heat emitted by a chunk of radioactive material-plutonium-238 for the Cassini spacecraft. Cassini journeyed as close to the sun as Venus and then far back to Saturn, spanning a much wider range of distances from the sun than Earth does during its yearly orbit. If the sun had an effect on plutonium decay, the fluctuations would have been much more substantial than those seen in Earth-bound experiments. As a result, Cooper reasoned, Cassini should have measured substantial changes in its generator’s output. It didn’t.
The Stanford/Symmetry article included something new. Peter Sturrock, Professor Emeritus of Applied Physics at Stanford, suggested is that some of the variation in the Radium-226 and Silicon-32 decay rates is related to solar rotation. From Evidence for Solar Influences on Nuclear Decay Rates
Recent reports of periodic fluctuations in nuclear decay data of certain isotopes have led to the suggestion that nuclear decay rates are being influenced by the Sun, perhaps via neutrinos. Here we present evidence for the existence of an additional periodicity that appears to be related to the Rieger periodicity well known in solar physics.
Links to the research reports can be found at Variability of Nuclear Decay rates. Search for “Research papers: PERIODIC VARIATIONS: SCALE OF DAYS OR YEARS” and “Research papers: NON-PERIODIC VARIATIONS:” Subheading “Of Cosmic Origin”. Thanks to arXiv.org information about current research in physics is easily accessible.
Peter Sturrock was my first course advisor when I was a graduate student in his department at Stanford, 1972-1975. At one point there I wanted to take a course in mathematical statistics. I was a little hesitant about this, since the subject is somewhat off the main direction of graduate study in physics. To my surprise, Professor Sturrock strongly encouraged me to do so. Whatever the conclusion about the relationship between the sun and radioactive decay may be, there will be a lot of statistical analysis along the way.
From Hilbert Space to Dilbert Space, and beyond 