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A Trojan Asteroid for Earth

by Paul Gilster | Jul 29, 2011 | Asteroid and Comet Deflection | 7 Comments

Although the asteroid temporarily called 2010 TK7 was discovered late in 2010, we now learn in the latest issue of Nature that this object is our planet's first known Trojan asteroid. The term refers to objects that orbit around one of the two Lagrangian points L4 and L5 -- these are found 60° ahead of and behind the larger body. Trojans come in various sizes. The Saturn system actually has Trojan moons (Telesto and Calypso, which accompany Tethys, and Helene and Polydeuces, which move in orbital configuration with Dione). Jupiter, Neptune, Mars and now the Earth have all been found to have Trojan asteroids associated with them. As the paper on this work points out, the viewing geometry poses problems for discovering Trojan asteroids moving with our planet, although we have found unusual objects like the 'horseshoe orbiters' 2010 SO16 and 3753 Cruithne. What made the current discovery possible was the Wide-field Infrared Survey Explorer (WISE) satellite, which searched large...

A Shield from Stellar Eruptions?

by Paul Gilster | Jul 28, 2011 | Exoplanetary Science | 33 Comments

We don't know whether life can exist on a planet circling a red dwarf, but as reported in these pages frequently in the last few years, there have been studies showing that liquid water could persist on the surface of such planets despite the fact that they would most likely be tidally locked, with one side always facing their star. So the potential is there, but we also have to account for flare activity and the question of how life might adapt to it. Perhaps there are protective mechanisms that might shield such planets from the worst such eruptions, a possibility now raised by Ofer Cohen (Harvard-Smithsonian Center for Astrophysics). Cohen and team have recently gone to work on planets of a far different kind -- hot Jupiters crowded up in tight orbits around more Sun-like stars -- but the work on gas giants is intended to lead on to a close look at red dwarf planets in similar proximity to violent stellar events. Until that study is complete, we can learn from their work on what...

Water in the Distant Universe

by Paul Gilster | Jul 27, 2011 | Deep Sky Astronomy & Telescopes | 11 Comments

Although I wasn't able to do any traveling during my recent week off, I did manage to get in some backed up reading, including Iain Banks' Use of Weapons (2008), the third in his series of novels about the interstellar civilization known as 'The Culture.' I've developed quite an interest in Banks, whose novels paint a future so finely textured that the memory of it lingers like a flashback to an actual experience, an intuitive, almost mystical sense that I remember having encountered when I first read Cordwainer Smith (Paul Linebarger) many years ago (some of Jay Lake's short stories also have this effect on me). Thanks to the many Centauri Dreams readers who put me on to Banks' novels. Among the events in astrophysics that occurred during my absence, I was most struck by the discovery of vast amounts of water surrounding a black hole more than 12 billion light years away, an indication, in the words of JPL's Matt Bradford, that "water is pervasive throughout the universe, even at...

A Brief Summer Break

by Paul Gilster | Jul 18, 2011 | Administrative | 39 Comments

It hasn't escaped my attention that in the past seven years, I've taken no more than a couple of days off at a time from writing Centauri Dreams posts. Now that the doldrums of summer are here in the northern hemisphere, it seems a good time to take a somewhat longer break. Not that I'll stay away if something major happens -- if Debra Fischer announces rocky worlds around Centauri B, for example, I'll be all over the story. But a week off will provide the chance to reflect, recharge, and get in some backed up but necessary reading. I'll plan to have the next Centauri Dreams post up, then, some time next week, probably by the 27th, and then back to normal.

Two Relatively Near Brown Dwarfs

by Paul Gilster | Jul 15, 2011 | Deep Sky Astronomy & Telescopes | 65 Comments

Two brown dwarfs relatively near to the Sun may be just the first such objects we'll soon identify with data from the WISE (Wide-field Infrared Survey Explorer) satellite. Ralf-Dieter Scholz (Leibniz-Institut für Astrophysik, Potsdam) and colleagues have gone to work on a search for brown dwarfs with high proper motion, looking for brown dwarfs in the immediate solar neighborhood using not just the preliminary WISE data release but the previous near-infrared (2MASS) and deep optical (SDSS) surveys. The search has already begun to pay off. The two brown dwarf discoveries -- WISE J0254+0223 and WISE J1741+2553 -- are at estimated distances of 15 and 18 light years respectively. Their strong infrared signature and their extremely faint appearance at visible wavelengths attracted the team's attention, and both show the high proper motion across the sky that flags nearby stellar objects. The team was able to use the Large Binocular Telescope (LBT) in Arizona to determine spectral type and...

A Binary System on the Edge of Merger

by Paul Gilster | Jul 14, 2011 | Deep Sky Astronomy & Telescopes | 15 Comments

A pair of white dwarf stars too close together to distinguish visually may help us in the hunt for gravitational waves, while potentially explaining a whole class of rare, relatively faint supernovae. The system in question -- called SDSS J065133.33+284423.3, or J0651 for short -- was found during a spectroscopic survey looking for extremely low mass white dwarfs. J0651 includes one white dwarf with about a quarter of the Sun's mass compacted down to Neptune-size, along with a companion white dwarf that is half the Sun's mass and about the size of the Earth. Usefully, this is a system oriented so that we can observe eclipses of each star by the other, which is how we can measure orbital parameters, masses and white dwarf radii. The General Theory of Relativity predicts that close pairs of stars produce gravitational waves that are ripples in the curvature of spacetime, and as the paper on the new work points out, the binary pulsar PSR B1913+16 has already given us indirect evidence...

A Neptunian Year Considered

by Paul Gilster | Jul 13, 2011 | Outer Solar System | 12 Comments

When the German astronomer Johann Gottfried Galle discovered Neptune on September 23, 1846, he found a world so distant from the Sun that its orbit takes 165 years to complete. With Neptune reaching its first complete revolution since discovery, an event that occurred yesterday, we can enjoy some celebratory Hubble imagery of the planet. I especially like the shot below, which not only shows atmospheric features but also has been tweaked to reveal some of Neptune's moons. The planet has about thirty moons, most of them too faint to appear in these images. Image: This illustration was composed from numerous separate Hubble Wide Field Camera 3 images. A color image composed of exposures made through three color filters shows the disk of Neptune, revealing clouds in its atmosphere. Forty-eight individual images from a single filter were brightened to reveal the very faint moons and composited with the color image. The white dots are Neptune's inner moons moving along their orbits during...

Supernovae: Factories of Cosmic Dust

by Paul Gilster | Jul 12, 2011 | Deep Sky Astronomy & Telescopes | 1 Comment

The supernova called SN 1987A is a prime object for scrutiny because it gives us the chance to see the various phases of stellar death over time. And as you might guess from the fact that it was visible to the naked eye when first detected back in 1987, it's located relatively nearby, in the Large Magellanic Cloud. Working in the far-infrared, the European Space Agency's Herschel space observatory has made new discoveries about SN 1987A while studying this small galaxy's cold dust emissions. The surprise result: SN 1987A is shrouded with enormous amounts of dust, 10,000 times more than previous estimates. The dust was at a temperature of roughly minus 256 to minus 249 degrees Celsius, making it a bit colder than Pluto (minus 240 degrees Celsius). These are the first far-infrared observations of this object, showing that the dust is emitting more than 200 times the energy of the Sun. Moreover, there is enough dust here to account for 200,000 planets the size of the Earth. Thus we...

Report from the UK Space Conference

by Paul Gilster | Jul 11, 2011 | Culture and Society | 19 Comments

By Rob Swinney Rob Swinney is a freelance writer, a member of the British Interplanetary Society and an active participant in the Tau Zero Foundation/BIS study group Project Icarus, a team of volunteers working on a practical design for an interstellar probe. Rob completed his Bachelors degree in Astronomy and Astrophysics at the University of Newcastle Upon Tyne and his Masters in Radio Astronomy at the University of Manchester (Jodrell Bank). Later he graduated from Cranfield University (then the Cranfield Institute of Technology) with a Masters degree in Avionics and Flight Control Systems. After a rewarding career in the Royal Air Force as an Aerosystems Engineer (Avionics) Officer he completed his Commision in 2006 having attained the rank of Squadron Leader. He is a Chartered Engineer registered with the UK's Engineering Council and a Member of the Institution of Engineering and Technology. Rob recently attended the UK Space Conference on July 4 and 5th and here offers us a...

Saturn: A Turbulent Early Spring

by Paul Gilster | Jul 7, 2011 | Outer Solar System | 10 Comments

I had been intending to cover recent news about Saturn in an upcoming post anyway, but the images below sealed the deal. They're further wonders from Cassini, pictures of a massive storm in Saturn's northern hemisphere that encircles the planet. First detected on December 5, 2010, the storm has been on the rampage ever since at about 35 degrees north latitude. It covers approximately 4 billion square kilometers. Cassini's radio and plasma wave science instrument has been showing a lightning flash rate 10 times that of any other storms the spacecraft has monitored since its arrival in Saturn orbit back in 2004. The flashes were so frequent at one point that Cassini could no longer resolve individual strokes, although the intensity has now eased. Image: The huge storm churning through the atmosphere in Saturn's northern hemisphere, seen here in a true-color view from NASA's Cassini spacecraft. This view looks toward the sunlit side of the rings from just above the ring plane. The...

Is the Space Age Over?

by Paul Gilster | Jul 6, 2011 | Culture and Society | 92 Comments

A good futurist can come up with all kinds of outcomes for humanity, but for those of us consumed by space exploration, a recent article in The Economist sketches a particularly bleak possibility. Forget about the stars. For that matter, forget about Mars, even the Moon. The new reality is emerging in the symbolic end of the Space Shuttle program and the eventual de-orbiting of the International Space Station. It's a reality based on a space program that fares no higher than geostationary orbit and the growing technosphere that encloses us like a planetary ring. The End of the Space Age is a cautionary tale about an all too real possibility, one that dismisses those anxious to move into the Solar System as 'space cadets,' while invoking the space ideas of the 1950s and 60s as an almost surreal excursion that quickly gave way to the outright fantasy of 'Star Trek.' The Economist will have none of the old optimism, the vision of ever expanding humanity pushing out to build an...

Spacetime Beyond the Planck Scale

by Paul Gilster | Jul 5, 2011 | Uncategorized | 21 Comments

Is the universe at the deepest level grainy? In other words, if you keep drilling down to smaller and smaller scales, do you reach a point where spacetime is, like the grains of sand on a beach, found in discrete units? It's an interesting thought in light of recent observations by ESA's Integral gamma-ray observatory, but before we get to Integral, I want to ponder the spacetime notion a bit further, using Brian Greene's superb new book The Hidden Reality as my guide. Because how spacetime is put together has obvious implications for our philosophy of science. Consider how we measure things, and the fact that we have to break phenomena into discrete units to make sense of them. Here's Greene's explanation: For the laws of physics to be computable, or even limit computable, the traditional reliance on real numbers would have to be abandoned. This would apply not just to space and time, usually described using coordinates whose values can range over the real numbers, but also for all...

Cosmos & Culture: A Review

by Paul Gilster | Jul 1, 2011 | Astrobiology and SETI | 31 Comments

By Larry Klaes Tau Zero journalist Larry Klaes gives us a look at a NASA publication whose authors tackle the biggest questions imaginable for our culture. Usefully, this volume, whose authors include major names in fields ranging from astrophysics to cultural evolution, is available online at no charge. As Larry points out, it deserves wide readership, for the issues of our place in the universe and how we respond to potential extraterrestrial contact via SETI will guide our future, both on Earth and in space. It is often difficult to get a wider perspective on existence, especially when you and the rest of your species have been stuck in one place for all but the smallest and most recent of times. This has certainly been the case with the species known as humanity. While a few ancient philosophers guessed that we live on a world surrounded by an immense amount of stars and space, it has only been in the last few centuries that both the scientific and general communities came to...

Charter

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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