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Dark Energy Paints the Void

by Paul Gilster | Aug 27, 2007 | Deep Sky Astronomy & Telescopes | 6 Comments

A vast, empty region in Eridanus may be giving us hints about the operation of dark energy in the distant universe. The region shows up on the Wilkinson Microwave Anisotropy Probe's map of the cosmic microwave background (CMB) radiation. The remnant of the Big Bang, the faint radio waves of the CMB provide the earliest picture we have of the cosmos. What the WMAP displayed to us was a view of its structure at a time just a few hundred thousand years after the Big Bang. The Eridanus region stands out on the WMAP data because it's slightly colder, and I do mean 'slightly' -- we're talking about temperature differences in the area of millionths of a degree. Two possibilities thus arise: The cold spot could be intrinsic to the CMB itself, a structural anomaly in the early universe. Or it could indicate something through which the CMB radiation had to pass on its way to our detectors. Now a study using data from the National Radio Astronomy Observatory VLA Sky Survey offers a possible...

Notes & Queries 8/25/07

by Paul Gilster | Aug 25, 2007 | Culture and Society | 16 Comments

Google Sky is a terrific idea, letting you roam at will through the heavens in a realm of high resolution imagery and information overlays that becomes a useful teaching tool as well as a dazzling personal excursion. The new feature mines imagery from the Space Telescope Science Institute, the Sloan Digital Sky Survey and many other sources. The latest version of Google Earth is needed to use it. To keep up with Google Sky developments, you should be reading Frank Taylor's Google Earth Blog, which now includes a 'Sky' category in its archives. Frank's original Sky announcement includes a video demonstrating how Google Sky works. ------- How many stars are in the Milky Way? I notice that SETI optimists tend to higher numbers, usually citing 400 billion, while SETI pessimists lean toward 200 or even 100 million (the number I remember being taught back in the 1960s). This outstanding video is optimistic indeed, claiming a whopping 500 billion, but whatever the number, its look at the...

Jupiter: Protection from Incoming Comets?

by Paul Gilster | Aug 24, 2007 | Outer Solar System | 29 Comments

Jupiter's protective role for Earth has long been assumed, the theory being that the giant planet deflects asteroids and comets away from the inner Solar System. But studies on the subject are sparse, and focus on long period comets in extremely elliptical orbits. What about short period comets, and in particular the Jupiter Family of Comets (JFC)? These are comets thought to originate in the Kuiper Belt whose orbits are now controlled by Jupiter. Comet 81P/Wild 2, encountered by Stardust, was one of these, as was Comet Shoemaker Levy-9. We all saw in 1994 what a planetary impact from a comet could do when Shoemaker Levy-9 struck Jupiter. And a new study suggests that Jupiter's presence offers Earth no real protection from such objects. A research team at the UK's Open University set up computer models that examined the Jupiter Family, defined for these purposes as comets whose semi-major axes are smaller than Jupiter's and whose orbital period is less than twenty years. Some studies...

A New View of Uranus’ Rings

by Paul Gilster | Aug 23, 2007 | Outer Solar System | 3 Comments

We're used to astronomical phenomena being relatively stable over the course of a human lifetime, which is why unexpected activity catches the eye. Think of the surprise over Io's volcanoes when they were first revealed by Voyager. And now we learn that the ring system around Uranus has changed significantly since Voyager 2 photographed it some twenty-one years ago. The inner rings have become more prominent, showing dusty material moving in otherwise empty regions of the rings. So reports Imke de Pater (UC-Berkeley), who led the team of astronomers investigating these changes, and presented the results at the European Planetary Science Congress today in Potsdam. Says de Pater of the activity: "People tend to think of the rings as unchanging, but our observations show that not to be the case. There are a lot of forces acting on small dust grains, so it is not that crazy to find that the arrangement of rings has changed." Assisting the investigation is the edge-on view we now have of...

17th Carnival of Space Available

by Paul Gilster | Aug 23, 2007 | Culture and Society | 0 Comments

The 17th Carnival of Space is now available, hosted by The Planetary Society's Emily Lakdawalla. Astronomy Down Under offers some useful advice on choosing binoculars for celestial observing, while Brian Wang's scenario for space technology in 2057 looks at what's coming through the lenses of nanotechnology, advanced fission and fusion. Will carbon nanotubes lead to high-performance solar sails? Plenty to speculate about in this one, and an interesting set of links all around.

Asteroids: An Outer Belt Anomaly

by Paul Gilster | Aug 22, 2007 | Outer Solar System | 11 Comments

Have scientists found a new category of asteroid? The evidence for basalt of a hitherto unseen composition on two small objects in the outer asteroid belt points to the possibility. An igneous rock, basalt would indicate that the asteroids were once part of a larger body, one that underwent some form of internal heating. The problem is that basalt is unusual for this part of the asteroid belt, nor is it clear whether the two fragments under study came from the same parent body. Add to that an unusual reflectance spectrum and the picture gets interesting indeed. The asteroids in question are (7472) Kumakiri and (10537) 1991 RY16, and therein lies a tale. The two were chosen from a group of six candidate asteroids thought to be classified as V-type, a name deriving from Vesta, the second largest of the asteroids. Not long ago it was thought that all basaltic V-type asteroids were simply fragments of Vesta, but in the past few years several V-type objects not belonging to this family...

A Neutron Star in the Neighborhood

by Paul Gilster | Aug 21, 2007 | Deep Sky Astronomy & Telescopes | 12 Comments

A long-time old movie buff, I am delighted with the choice of name for a recently discovered neutron star that may be the closest such object to Earth. It's being called Calvera, after the bandit played so brilliantly by Eli Wallach in the 1960 western The Magnificent Seven. In astronomical terms, the 'Magnificent Seven' are the seven isolated neutron stars -- neutron stars with no associated binary companion, supernova remnant or radio pulsations -- known until the discovery of Calvera, which brings the number to eight. Co-discoverer Derek Fox (Penn State) calls the choice of names "...a bit of an inside joke on our part." And indeed, Calvera started life with a far less interesting name. The German-American ROSAT satellite (named after x-ray discoverer Wilhelm Röntgen) had compiled 18,000 x-ray sources. Comparing these with catalogs of visible, infrared and radio objects, Robert Rutledge (McGill University) discovered that the source known as 1RXS J141256.0+792204 had no known...

Voyager Interstellar Mission Proceeds

by Paul Gilster | Aug 20, 2007 | Interstellar Medium | 3 Comments

I don't want today to pass without noting that it is the thirtieth anniversary of the launch of Voyager 2. Both Voyagers remain healthy, continuing studies of the solar wind, magnetic fields and energetic particles with their five functioning science instruments. As this JPL news release notes, the Voyagers run on less than 300 watts of power, which they tap from radioisotope thermoelectric generators. At 15.5 billion kilometers (Voyager 1) and 12.5 billion (Voyager 2), the vehicles are the farthest human-made objects, unable to use the power of distant Sol. Image: Artist concept of the two Voyager spacecraft as they approach interstellar space. Image credit: NASA/JPL. So our first mission into nearby interstellar space continues to go quite well, with both spacecraft reporting home despite one-way radio travel times of fourteen and twelve hours respectively. Voyager 1 seems to have encountered the heliosheath -- where the solar wind slows as it encounters the thin gas between the...

Can Titan Keep Its Atmosphere?

by Paul Gilster | Aug 20, 2007 | Outer Solar System | 5 Comments

With the European Planetary Science Congress now in session in Potsdam, we should have several interesting presentations to discuss this week, the first of which involves Titan. Huygens and Cassini have shown us a frigid, rocky surface under a surreal orange cloud of hydrocarbons, a place where liquid methane seems to flow in lakebeds and rivers. Methane in these circumstances plays much the same role that water plays here on Earth. Image: The surface of Titan as seen by the Huygens probe. Credit: ESA/NASA/JPL/University of Arizona. But what's under that interesting surface? The permafrost crust seems to sit on a soggy layer of ammonia, methane and water, beneath which an icy layer should surround a rocky core. It's that icy layer that interests Vasili Dimitrov (Tel-Aviv University), who is discussing its nature at the Potsdam conference. Dr. Dimitrov is hoping to put limits on the methane reserve available within Titan, which will tell us, among other things, whether that thick...

Remembering Ronald Bracewell

by Paul Gilster | Aug 18, 2007 | Culture and Society | 3 Comments

The scientific world has lost a true renaissance man (and indeed, one with an interest in Renaissance-era technology) with the death of Ronald Bracewell. The intellect of the Stanford mathematician, physicist and radio engineer ranged across many disciplines, nursing a fascination with etymology, cataloguing varieties of California trees, developing his university's radio astronomy capabilities and of course, speculating on extraterrestrial civilizations and how they might reach us. The Stanford News Service offers an overview of his rich and crowded life. Bracewell's work had wide repercussions, as Umran Inan, professor of electrical engineering at Stanford, recalls: "Many of Ron's inventions have flourished in other fields of science and engineering. For example, CAT scans and, basically, the imaging of objects by scanning them through radio and electromagnetic methods are all things that originated with him." For those of us focused on space, Bracewell's work on radiotelescopes...

The ‘Wow Signal’ Reexamined

by Paul Gilster | Aug 18, 2007 | Astrobiology and SETI | 5 Comments

James Brown continues to run SETI.net, a privately-funded SETI search program using off-the-shelf components and software created by himself. Brown's work may well be unique, for there seems to be no other working station collecting data that is run by amateur radio astronomers, and that poses a problem for observations like the recent series Brown has made at the frequency and coordinates of the so-called 'Wow Signal,' which was received just over thirty years ago on August 15, 1977. The problem, of course, is that when Brown notes something of interest, he needs corroboration. If you are in the ranks of amateur SETI or radio astronomy enthusiasts and can coordinate observations with SETI.net, you'll want to check Brown's recent work (scroll to the bottom of the page) and contact him for further information. The Wow Signal was detected by Jerry Ehman at the Ohio State University Radio Observatory (known as the Big Ear). The signal, strong enough to elicit Ehman's inscribed comment...

Propulsion Clues from a Dark Universe

by Paul Gilster | Aug 17, 2007 | Exotic Physics | 23 Comments

If you had a device that could manipulate the expansion of spacetime, would you have the makings of a stardrive? Miguel Alcubierre's 'warp drive' concept is based on something like this. The physicist's 1994 paper points out that the speed of light constraint applies to objects moving within spacetime, but makes no prediction about how fast spacetime itself can move. Inflation theories draw on the same idea, with the early universe suddenly expanding at rates far surpassing light speed. So think about contracting space in front of your vehicle while creating more space behind it. Distorted spacetime carries the starship along at fantastic velocities while violating no principle dear to Einstein. The trick, of course, is energy, the necessary amount of which has been discussed in various papers. As far as I know, no one has been able to get the figure down below the total energy output of a Sun-like star, but that's a big reduction over earlier views that it would take all the energy...

Faster than Light in the Laboratory?

by Paul Gilster | Aug 16, 2007 | Exotic Physics | 7 Comments

Can photons move faster than the speed of light? You wouldn't think so, not if the name 'Einstein' has resonance, but Günter Nimtz and Alfons Stahlhofen (University of Koblenz) have been working on so-called quantum tunneling, joining two glass prisms and feeding microwave light into them. Tunneling occurs when a particle jumps an apparently uncrossable gap, and that's just what the team's microwave photons appear to have done, at least a few of them, when the prisms were separated. The bulk of the microwaves were reflected by the first prism. New Scientist will soon be reporting on this story, which picks up on the German researchers' recent paper. The tunneling photons seem to have reached the detector at the same time that their non-tunneling cousins did, suggesting movement far beyond the speed of light. The tunneling time evidently did not change when the prisms were pulled further apart. Is this a violaton of relativity? Perhaps not. Note this from the New Scientist story,...

A Frigid Enceladus After All

by Paul Gilster | Aug 16, 2007 | Outer Solar System | 3 Comments

We always knew the surface of Enceladus was cold, but those tantalizing plumes breaking out of the Saturnian moon's south polar region gave hope of warmer things within. Liquid water fits with one model, pockets of which could account for the occasional geysers of ice crystals mixing with methane, nitrogen and carbon dioxide that Cassini has measured. Fill Enceladus with an internal ocean and the possibility of some kind of biology becomes an attractive study. But an alternate take on the plumes has been on view for some time now. Coming out of the University of Illinois, it's based on the idea that stiff compounds of ice called clathrates may cover Enceladus to a considerable depth. Whereas the warm interior model could produce such geysers, coined 'Cold Faithful' out of analogy to Yellowstone National Park's Old Faithful geyser, so could the clathrate model. But the latter, dubbed 'Frigid Faithful,' could operate far below the freezing point of water, with obvious implications for...

Carnival of Space #16 Available

by Paul Gilster | Aug 16, 2007 | Culture and Society | 1 Comment

Carnival of Space #16 is now available at Brian Wang's Advanced Nanotechnology site. Particularly recommended is an essay we also looked at recently here, Alex Bonnici's discussion of Dandridge Cole and his visionary outlook on using asteroids for the good of mankind. And you'll also want to read Mark Whittington's look at what the next fifty years may bring in space travel. If fifty years rings a bell, it may be because you're thinking of the upcoming anniversary of Sputnik. Let's hope the next fifty years manage a more consistent pace of development...

Mira: Star with a Comet-like Tail

by Paul Gilster | Aug 15, 2007 | Deep Sky Astronomy & Telescopes | 12 Comments

GALEX -- the Galaxy Evolution Explorer -- was an interesting mission to begin with, a space-based observatory conducting an all-sky survey of distant galaxies at ultraviolet wavelengths. Now it's come up with a real newsmaker, a star moving at an unusually fast 130 kilometers a second and sporting a comet-like tail. The material blowing off the red giant Mira is, in fact, forming a wake some thirteen light years long. No such phenomenon has ever been seen around a star before. Image: Mira appears as a small white dot in the bulb-shaped structure at right, and is moving from left to right in this view. The shed material can be seen in light blue. The dots in the picture are stars and distant galaxies. The large blue dot at left is a star that is closer to us than Mira. Credit: NASA/JPL-Caltech. From what GALEX is telling us, the elements Mira is leaving behind, including carbon, oxygen and other building blocks for future star and planet formation, have been shed over a period of...

HAT-P-3b: Heavy Elements in Transit

by Paul Gilster | Aug 14, 2007 | Exoplanetary Science | 4 Comments

The Hungarian Automated Telescope Network (HATNet) is run out of the Harvard-Smithsonian Center for Astrophysics, with primary stations at Mauna Kea (HI) and on Mt. Hopkins (Arizona). Looking at large fields of stars over many consecutive nights, the automated telescopes involved help astronomers identify the periodic dimming that marks a transiting exoplanet. And with other projects like the Trans-Atlantic Exoplanet Survey (TrES), the XO Project in Maui and the Optical Gravitational Lensing Experiment (OGLE) in Chile operational, transit data are piling up. All of which is useful indeed, for at present we are just nearing 20 transiting planets detected from ground-based observatories. The discovery paper for the most recent HATnet detection makes an interesting point about the size of our sample, declaring it "...still small enough that individual discoveries often advance our understanding of these objects significantly by pushing the limits of parameter space, either in planet...

Lonely Minds in the Universe (Review)

by Paul Gilster | Aug 14, 2007 | Culture and Society | 1 Comment

by Bernd Henschenmacher Giancarlo Genta's new book Lonely Minds in the Universe deals with many aspects of the search for extraterrestrial life and intelligence. As does Michael Michaud in his Contact with Alien Civilizations, Genta examines the scientific and philosophical implications of such contact. The book begins with an overview of Western thought on the subject from the ancient Greeks to the late 20th Century, including the question of how extraterrestrial contact might affect human religious beliefs. The book's astrobiological chapters offer a rapid introduction to this emerging science. Readers who are familiar with concepts like habitable zones, speculations about life on Mars, Europa or Titan and the concept of a galactic habitable zone will find little new here, but this section offers a well written and easy to understand backgrounder. The book's treatment of evolution, intelligence and consciousness -- including the problem of defining consciousness itself -- is...

An Early Mission for Exoplanet Imaging

by Paul Gilster | Aug 13, 2007 | Exoplanetary Science | 7 Comments

With the European Space Agency's DARWIN at least a decade off and funding for the Terrestrial Planet Finder as problematic as ever, what would be a suitable interim mission to extend our exoplanet exploration program? COROT is already flying, with the possibility of detecting large terrestrial planets in close orbits, while Kepler should be able to detect Earth-mass planets in Earth-like orbits by 2013 or earlier. All of which is promising, but we're still missing key elements of the puzzle. Take those transiting exoplanets COROT and Kepler track. We'll retrieve a wealth of data, but we probably won't be able to get the kind of spectroscopic information we'd like to see from a more advanced mission. Similarly, ground-based telescopes using adaptive optics, and future space missions like the James Webb Space Telescope should show us hot gas giants, but we'll be unlikely to see planets like our own Jupiter and Saturn, cooler worlds in more distant orbits. The solution? A team of NASA...

Notes & Queries 8/11/07

by Paul Gilster | Aug 11, 2007 | Culture and Society | 2 Comments

American aerospace engineer Dandridge MacFarland Cole, who died just over forty years ago, was an early advocate of exploring the asteroids, advocating their eventual colonization in his book Islands in Space: The Challenge of the Planetoids. Alex Michael Bonnici takes a look at this fascinating figure, placing him in the tradition of Tsiolkovsky and Goddard as a futurist whose thinking challenged us to think big. Among his startling ideas was the use of asteroids as interstellar arks or generation ships. Bonnici's tribute is well deserved and highly recommended. ------- The Galaxy Zoo continues to draw remarkable traffic. Launched in mid-July, this project to categorize galactic images taps the volunteer efforts of users from all over the planet. Users have thus far inspected almost seven million images and produced more than 12.3 million galaxy classifications. The Galaxy Zoo has now enrolled 85,000 participants, and is again demonstrating the power of networking to do things...

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In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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