Forum Reaches its First Birthday

Exactly one year today I was nagged into setting up the Universe Today forum as a way for space enthusiasts to come together and discuss all things space and astronomy. Despite my initial reluctance, it’s been incredibly successful, becoming one of the larger communities of this topic on the Internet – I wish I’d done it sooner. As I’m looking right now, we have 2422 members who’ve written 34354 posts. So, I’d like to make a special thanks to all the contributors, moderators, and experts who have participated so far, I really appreciate all your hard work.

If you have questions about space, want to explore any topic deeper, or just make friends who share your interests in space, come and join us.

Fraser Cain
Universe Today

P.S. If you’ve had problems accessing the forum, or setting up an account, let me know, and I’d be happy to help you out. I know it can be a little confusing if you’ve never joined one before.

Wallpaper: Saturn’s Rings in Ultraviolet

The best view ever of Saturn’s rings in the ultraviolet indicates there is more ice toward the outer part of the rings, hinting at ring origin and evolution, say two University of Colorado at Boulder researchers involved in the Cassini mission.

Researchers from CU-Boulder’s Laboratory for Atmospheric and Space Physics, Joshua Colwell and Larry Esposito, said the UV spectra taken during the Cassini spacecraft’s orbital insertion June 30 show definite compositional variation in the A, B and C rings.

Esposito, who discovered the F ring around Saturn in 1979 using Pioneer 11 data, is the team leader for Cassini’s Ultraviolet Imaging Spectrograph, or UVIS, a $12.5 million instrument riding on the spacecraft. A UVIS team member and ring expert, Colwell created the color-enhanced images from the spectra.

The CU-Boulder built UVIS instrument is capable of resolving the rings to show features up to 60 miles across, roughly 10 times the resolution obtained by the Voyager 2 spacecraft. The instrument was able to resolve the “Cassini division,” discovered by Giovanni Domenico Cassini in the 17th century, which separates the A and B rings of Saturn, proving the rings are not one contiguous feature.

The ring system begins from the inside out with the D, C, B and A rings followed by the F, G and E rings. The red in both images indicates sparser ringlets likely made of “dirty,” and possibly smaller, particles than in the denser, icier turquoise ringlets.

Original Source: University of Colorado News Release

SpaceShipOne Problem Resolved

Wired News is reporting that Burt Rutan has resolved the nearly catastrophic problems that cropped up during SpaceShipOne’s historic flight into space last flight. After his flight, pilot Mike Melvill said that a control malfunctioned, caused the rocket plane to roll 90 degrees over to the left, and then 90 degrees to the right when he tried to compensate. Melvill was able to use a backup system, and still reach 100 km of altitude. Rutan said that the problem was traced to an actuator that had ?run against a stop?, limiting its movement. With the problem fixed, SpaceShipOne’s next flight will be an attempt to win the $10 million X-Prize.

Brown Dwarf Pair Discovered

Today at the 13th Cambridge Workshop on “Cool Stars, Stellar Systems, and the Sun,” Dr. Kevin L. Luhman (Harvard-Smithsonian Center for Astrophysics) announced the discovery of a unique pair of newborn brown dwarfs in orbit around each other. Brown dwarfs are a relatively new class of objects discovered in the mid-1990s that are too small to ignite hydrogen fusion and shine as stars, yet too big to be considered planets. “Are brown dwarfs miniature failed stars, or super-sized planets, or are they altogether different from either stars or planets?” asks Luhman. The unique nature of this new brown dwarf pair has brought astronomers a step closer to the answer.

One possible explanation for the origin of brown dwarfs is that they are born in the same way as stars. Stars form in huge interstellar clouds in which gravity causes clumps of gas and dust to collapse into “seeds,” which then steadily pull in more and more material until they grow to become stars. However, when this process is studied in detail by computer, many simulations fail to produce brown dwarfs. Instead, all the seeds grow into full-fledged stars. This result led some astronomers to wonder if brown dwarfs and stars are created in different ways.

“In one alternative that has been proposed recently,” explains Luhman, “the seeds in an interstellar cloud pull on each other through their gravity, causing a slingshot effect and ejecting some of the seeds from the cloud before they have a chance to grow into stars. These small bodies are what we see as brown dwarfs, according to that hypothesis.”

Testing these ideas for the birth of brown dwarfs is hampered by the fact that brown dwarfs are normally extremely faint and hard to detect in the sky. For most of their lives, they are not hot enough to ignite hydrogen fusion, so they do not shine brightly like stars, and instead are relatively dim like planets. However, for a short time immediately following their birth, brown dwarfs are relatively bright due to the leftover heat from their formation. As a result, brown dwarfs are easiest to find and study at an age of around 1 million years, which is newborn compared to the 4.5 billion year age of our Sun.

Taking advantage of this fact, Luhman searched for newborn brown dwarfs in a cluster of young stars located 540 light-years away in the southern constellation of Chamaeleon. Luhman conducted his search using one of the two 6.5-meter-diameter Magellan telescopes at Las Campanas Observatory in Chile, which are among the largest telescopes in the world.

Of the two dozen new brown dwarfs found, most were isolated and floating in space by themselves. However, Luhman discovered one pair of brown dwarfs orbiting each other at a remarkably wide separation. All previously known pairs of brown dwarfs are relatively close to each other, less than half the distance of Pluto from the Sun. But the brown dwarfs in this new pair are much farther apart, about six times the distance of Pluto from the Sun.

Because these brown dwarfs are so far apart, they are very weakly bound to each other by gravity, and the slightest tug would permanently separate them. Therefore, Luhman concludes, “The mere existence of this extremely fragile pair indicates that these brown dwarfs were never subjected to the kind of violent gravitational pulls that they would undergo if they had formed as ejected seeds. Instead, it is likely that these baby brown dwarfs formed in the same way as stars, in a relatively gentle and undisturbed manner.”

Dr. Alan P. Boss (Carnegie Institution) agrees, stating, “Luhman’s discovery strengthens the case for the formation mechanism of brown dwarfs being similar to that of stars like the Sun, and hence for brown dwarfs being worthy of being termed ‘stars,’ even if they are too low in mass to be able to undergo sustained nuclear fusion.”

The discovery of this binary brown dwarf will be published in an upcoming issue of The Astrophysical Journal. The discovery paper currently is online in PDF format at

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

The Magellan telescopes are operated by the Carnegie Institution of Washington, the University of Arizona, Harvard University, the University of Michigan, and the Massachusetts Institute of Technology.

Las Campanas Observatory is operated by the Carnegie Observatories, which was founded in 1904 by George Ellery Hale. It is one of six departments of the private, nonprofit Carnegie Institution of Washington, a pioneering force in basic scientific research since 1902.

Original Source: Harvard CfA News Release

Heavy Galaxies Evolved Early

Current theories of the formation of galaxies are based on the hierarchical merging of smaller entities into larger and larger structures, starting from about the size of a stellar globular cluster and ending with clusters of galaxies. According to this scenario, it is assumed that no massive galaxies existed in the young universe.

However, this view may now have to be revised. Using the multi-mode FORS2 instrument on the Very Large Telescope at Paranal, a team of Italian astronomers have identified four remote galaxies, several times more massive than the Milky Way galaxy, or as massive as the heaviest galaxies in the present-day universe. Those galaxies must have formed when the Universe was only about 2,000 million years old, that is some 12,000 million years ago.

The newly discovered objects may be members of a population of old massive galaxies undetected until now.

The existence of such systems shows that the build-up of massive elliptical galaxies was much faster in the early Universe than expected from current theory.

Hierarchical merging
Galaxies are like islands in the Universe, made of stars as well as dust and gas clouds. They come in different sizes and shapes. Astronomers generally distinguish between spiral galaxies – like our own Milky Way, NGC 1232 or the famous Andromeda galaxy – and elliptical galaxies, the latter mostly containing old stars and having very little dust or gas. Some galaxies are intermediate between spirals and ellipticals and are referred to as lenticular or spheroidal galaxies.

Galaxies are not only distinct in shape, they also vary in size: some may be as “light” as a stellar globular cluster in our Milky Way (i.e. they contain about the equivalent of a few million Suns) while others may be more massive than a million million Suns. Presently, more than half of the stars in the Universe are located in massive spheroidal galaxies.

One of the main open questions of modern astrophysics and cosmology is how and when galaxies formed and evolved starting from the primordial gas that filled the early Universe. In the most popular current theory, galaxies in the local Universe are the result of a relatively slow process where small and less massive galaxies merge to gradually build up bigger and more massive galaxies. In this scenario, dubbed “hierarchical merging”, the young Universe was populated by small galaxies with little mass, whereas the present Universe contains large, old and massive galaxies – the very last to form in the final stage of a slow assembling process.

If this scenario were true, then one should not be able to find massive elliptical galaxies in the young universe. Or, in other words, due to the finite speed of light, there should be no such massive galaxies very far from us. And indeed, until now no old elliptical galaxy was known beyond a radio-galaxy at redshift 1.55 that was discovered almost ten years ago.

The K20 survey
In order to better understand the formation process of galaxies and to verify if the hierarchical merging scenario is valid, a team of Italian and ESO astronomers used ESO’s Very Large Telescope as a “time machine” to do a search for very remote elliptical galaxies. However, this is not trivial. Distant elliptical galaxies, with their content of old and red stars, must be very faint objects indeed at optical wavelengths as the bulk of their light is redshifted into the infrared part of the spectrum. Remote elliptical galaxies are thus among the most difficult observational targets even for the largest telescopes; this is also why the 1.55 redshift record has persisted for so long.

But this challenge did not stop the researchers. They obtained deep optical spectroscopy with the multi-mode FORS2 instrument on the VLT for a sample of 546 faint objects found in a sky area of 52 arcmin2 (or about one tenth of the area of the Full Moon) known as the K20 field, and which partly overlaps with the GOODS-South area. Their perseverance paid off and they were rewarded by the discovery of four old, massive galaxies with redshifts between 1.6 and 1.9. These galaxies are seen when the Universe was only about 25% of its present age of 13,700 million years.

For one of the galaxies, the K20 team benefited also from the database of publicly available spectra in the GOODS-South area taken by the ESO/GOODS team.

A new population of galaxies
The newly discovered galaxies are thus seen when the Universe was about 3,500 million years old, i.e. 10,000 million years ago. But from the spectra taken, it appears that these galaxies contain stars with ages between 1,000 and 2,000 million years. This implies that the galaxies must have formed accordingly earlier, and that they must have essentially completed their assembly at a moment when the Universe was only 1,500 to 2,500 million years old.

The galaxies appear to have masses in excess of one hundred thousand million solar masses and they are therefore of sizes similar to the most massive galaxies in the present-day Universe. Complementary images taken within the GOODS (“The Great Observatories Origins Deep Survey”) survey by the Hubble Space Telescope show that these galaxies have structures and shapes more or less identical to those of the present-day massive elliptical galaxies.

The new observations have therefore revealed a new population of very old and massive galaxies.

The existence of such massive and old spheroidal galaxies in the early Universe shows that the assembly of the present-day massive elliptical galaxies started much earlier and was much faster than predicted by the hierarchical merging theory. Says Andrea Cimatti (INAF, Firenze, Italy), leader of the team: “Our new study now raises fundamental questions about our understanding and knowledge of the processes that regulated the genesis and the evolutionary history of the Universe and its structures.”

Original Source: ESO News Release

Gaia Will Map a Billion Stars

One of ESA?s most ambitious current projects has the aim of compiling the most precise map of one thousand million stars in our Galaxy.

Gaia, a spacecraft which will carry two of the most sensitive cameras ever made, is due to be launched in 2010.

It will take five years to detect such a vast quantity of objects, some of which are incredibly faint, and another three years to plot them all in a giant three-dimensional computerised model that shows not only their current position, but their direction of motion, colour and even their composition.

In short, Gaia will produce a completely new view of the Galaxy and everything in it. It will produce the ultimate map, a star catalogue that could be used by every other space mission of the future.

Another exciting aspect of this amazing mission is that it could find objects that we did not know existed – until Gaia turns its supersensitive cameras in their direction. As well as stars, we may find other objects that are very faint, or in areas of the sky where we have not looked in depth yet.

One interesting area of the sky that will be viewed by Gaia is the ?blindspot? found between the Sun and Earth?s orbit.

From Earth, we can only observe this area during the daytime (and even then only on clear days without cloud cover), but it is very hard to pick out small objects such as asteroids, because the Sun?s glare renders them virtually invisible.

These asteroids are sometimes moving near enough to Earth to cause concern, but we may not find out about them until they have moved far enough away from the Sun to be seen by a telescope. One particular large group of asteroids, known as the Atens, spends its time weaving between the Sun and Earth?s orbit.

We know very little about these families of asteroids following the same orbit. They regularly cross the Earth?s orbit, which makes them at least a potential threat, although most of them are not an actual danger to our planet. However, we need to understand why they are there, where they come from and what they are made of.

With the help of its bird?s eye view from space, and its unprecedented accuracy, Gaia is the ideal candidate for keeping track of the Atens, and similar families of asteroids coming close to our home.

But asteroids and Solar System objects will comprise only a tiny fraction of the objects that Gaia will study. Their detection is a by-product of the main goal of Gaia which is to precisely measure the location, motion and composition of several millions of stars in our Galaxy.

Armed with this information we will gain new insight into the life cycle of our Galaxy and its future.

Original Source: ESA News Release

Sea Launch Investigation Begins

The Sea Launch team is gathering and reviewing Telstar 18 mission data to understand the sequence of events that led to a premature shutdown of the Sea Launch Zenit-3SL upper stage during that mission earlier this week.

The Zenit-3SL launch vehicle lifted off from the equatorial launch site on June 28 at 8:59pm PDT, (3:59 GMT, June 29) as scheduled, deploying Loral?s Telstar 18 communications satellite into orbit with a separated mass of 4,640 kg (10,229 lb.). Based on preliminary flight data, all Sea Launch system flight parameters were nominal except that the upper stage of the launch vehicle shut down about 54 seconds prematurely, following the second of two planned burns of the upper stage. The early shutdown caused the satellite to be released into an orbit with an apogee of 21,605 km, some 14,000 km short of the 35,786 km target apogee.

Space Systems/Loral confirmed spacecraft signal acquisition by a ground station in Perth, Australia, soon after separation and reported that the satellite was operating normally. Loral Space & Communications has replanned the mission and, if successful, the satellite has sufficient on-board fuel to bring it to its final orbital position and meet or exceed its 13-year specified life. Loral also reported the Telstar 18 spacecraft has deployed its solar arrays and all systems on the spacecraft are functioning as designed.

The cause of the rocket?s upper stage premature shutdown is under investigation by an Energia-appointed commission. Sea Launch will also form an independent review board to evaluate all findings and confirm that any corrective actions associated with the upper stage performance on the Telstar 18 mission are complete, satisfactory and verified. At this point in time, Sea Launch is optimistic it will conclude the board?s investigation and complete two more launches this year, as originally planned.

Sea Launch remains highly confident in the robust capability of the Zenit-3SL system, including the upper stage. This component remains one of the premiere upper stages in the industry, with an overall success rate of approximately 97%.

Sea Launch Company, LLC, headquartered in Long Beach, Calif., and marketed through Boeing Launch Services ( ), is the world?s most reliable commercial heavy-lift launch services provider. This multinational partnership offers the most direct and cost-effective route to geostationary orbit. With the advantage of a launch site on the Equator, the reliable Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, offering best value plus schedule assurance. For additional information and images of this mission, please visit the Sea Launch website at:

Original Source: Boeing News Release

Rings Pose New Mysteries

Just two days after the Cassini spacecraft entered Saturn orbit, preliminary science results are already beginning to show a complex and fascinating planetary system.

One early result intriguing scientists concerns Saturn?s Cassini Division, the large gap between the A and B rings. While Saturn?s rings are almost exclusively composed of water ice, new findings show the Cassini Division contains relatively more “dirt” than ice. Further, the particles between the rings seem remarkably similar to the dark material that scientists saw on Saturn?s moon, Phoebe. These dark particles refuel the theory that the rings might be the remnants of a moon. The F ring was also found to contain more dirt.

Another instrument on Cassini has detected large quantities of oxygen at the edge of the rings. Scientists are still trying to understand these results, but they think the oxygen may be left over from a collision that occurred as recently as January of this year.

“In just two days, our ideas about the rings have been expanded tremendously,” said Dr. Linda Spilker, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., deputy project scientist for the Cassini-Huygens mission. “The Phoebe-like material is a big surprise. What puzzles us is that the A and B rings are so clean and the Cassini Division between them appears so dirty.”

The visual and infrared mapping spectrometer onboard Cassini revealed the dirt mixed with the ice in the Cassini Division and in other small gaps in the rings, as well as in the F ring.

“The surprising fingerprint in the data is that the dirt appears similar to what we saw at Phoebe. In the next several months we will be looking for the origin of this material,” said Dr. Roger Clark, of the U.S. Geological Survey, Denver, Colo., and a member of the Cassini science team.

Cassini’s ultraviolet imaging instrument detected the sudden and surprising increase in the amount of atomic oxygen at the edge of the rings. The finding leads scientists to hypothesize that something may have collided with the main rings, producing the excess oxygen.

Dr. Donald Shemansky of the University of Southern California, Los Angeles, co-investigator for Cassini’s ultraviolet imaging spectrograph instrument, said, “What is surprising is the evidence of a strong, sudden event during the observation period causing substantial variation in the oxygen distribution and abundance.” Although atomic oxygen has not been previously observed, its presence is not a surprise because hydroxyl was discovered earlier from Hubble Space Telescope observations, and these chemicals are both products of water chemistry.

Cassini’s examination of Saturn’s atmosphere began while the spacecraft was still approaching the planet. Winds on Saturn near the equator decrease dramatically with altitude above the cloud tops. The winds fall off by as much 140 meters per second (approximately 300 miles per hour) over an altitude range of 300 kilometers (approximately 200 miles) in the upper stratosphere. This is the first time winds have been measured at altitudes so high in Saturn’s atmosphere.

“We are finally defining the wind field in three dimensions, and it is very complex,” said Dr. Michael Flasar of NASA Goddard Space Flight Center, Greenbelt, Md., principal investigator for Cassini’s composite infrared spectrometer. “Temperature maps obtained now that Cassini is orbiting Saturn are expected to show more detail, helping us to unravel the riddles of Saturn’s winds above the cloud tops.”

Early Friday (Pacific Time), Cassini imaged Saturn?s largest moon Titan, one of the prime targets for the mission. Titan is thought to harbor simple organic compounds that may be important in understanding the chemical building blocks that led to life on Earth. Although too cold to support life now, Titan serves as a frozen vault to see what early Earth might have been like. Scientists will receive the new data and images from Titan later Friday.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.

For the latest images and more information about the Cassini-Huygens mission, visit and

Original Source: NASA/JPL News Release

Cassini Makes Its First Titan Flyby

The Cassini spacecraft has revealed surface details of Saturn’s moon Titan and imaged a huge cloud of gas surrounding the planet-sized moon.

Cassini gathered data before and during a distant flyby of the orange moon yesterday. Titan’s dense atmosphere is opaque at most wavelengths, but the spacecraft captured some surface details, including a possible crater, through wavelengths in which the atmosphere is clear.

“Although the initial images appear bland and hard to interpret, we’re happy to report that, with a combination of instruments, we have indeed seen Titan’s surface with unprecedented clarity. We also look forward to future, much closer flybys and use of radar for much greater levels of surface detail,” said Dr. Dennis Matson of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., project scientist for the international Cassini-Huygens mission.

Cassini’s visible and infrared mapping spectrometer pierced the smog that enshrouds Titan. This instrument, capable of mapping mineral and chemical features of the moon, reveals an exotic surface bearing a variety of materials in the south and a circular feature that may be a crater in the north. Near-infrared colors, some three times redder than the human eye can see, reveal the surface with unusual clarity.

“At some wavelengths, we see dark regions of relatively pure water ice and brighter regions with a much higher amount of non-ice materials, such as simple hydrocarbons. This is different from what we expected. It’s preliminary, but it may change the way we interpret light and dark areas on Titan,” said JPL’s Dr. Kevin Baines, Cassini science-team member. “A methane cloud is visible near the south pole. It’s made of unusually large particles compared to the typical haze particles surrounding the moon, suggesting a dynamically active atmosphere there.”

This is the first time scientists are able to map the mineralogy of Titan. Using hundreds of wavelengths, many of which have never been used in Titan imaging before, they are creating a global map showing distributions of hydrocarbon-rich regions and areas of icy material.

Cassini’s camera also sees through the haze in some wavelengths. “We’re seeing a totally alien surface,” said Dr. Elizabeth Turtle of the University of Arizona, Tucson. “There are linear features, circular features, curvilinear features. These suggest geologic activity on Titan, but we really don’t know how to interpret them yet. We’ve got some exciting work cut out for us.”

Since entering orbit, Cassini has also provided the first view of a vast swarm of hydrogen molecules surrounding Titan well beyond the top of Titan’s atmosphere. Cassini’s magnetospheric imaging instrument, first of its kind on any interplanetary mission, provided images of the huge cloud sweeping along with Titan in orbit around Saturn. The cloud is so big that Saturn and its rings would fit within it. “The top of Titan’s atmosphere is being bombarded by highly energetic particles in Saturn’s radiation belts, and that is knocking away this neutral gas,” said Dr. Stamatios Krimigis of Johns Hopkins Applied Physics Laboratory, Laurel, Md., principal investigator for the magnetospheric imager. “In effect, Titan is gradually losing material from the top of its atmosphere, and that material is being dragged around Saturn.”

The study of Titan, Saturn’s largest moon, is one of the major goals of the Cassini-Huygens mission. Titan may preserve in deep-freeze many chemical compounds that preceded life on Earth. Friday’s flyby at a closest distance of 339,000 kilometers (210,600 miles) provided Cassini’s best look at Titan so far, but over the next four years, the orbiter will execute 45 Titan flybys as close as approximately 950 kilometers (590 miles). This will permit high-resolution mapping of the moon’s surface with an imaging radar instrument, which can see through the opaque haze of Titan’s upper atmosphere. In January 2005, the Huygens probe that is now attached to Cassini will descend through Titan’s atmosphere to the surface.

During the ring plane crossing, the radio and plasma wave science instrument on Cassini measured little puffs of plasma produced by dust impacts. While crossing the plane of Saturn’s rings, the instrument detected up to 680 dust hits per second. “The particles are comparable in size to particles in cigarette smoke,” said Dr. Don Gurnett of the University of Iowa, Iowa City, principal investigator for the instrument. “When we crossed the ring plane, we had roughly 100,000 total dust hits to the spacecraft in less than five minutes. We converted these into audible sounds that resemble hail hitting a tin roof.”

The spacecraft reported no unusual activity due to the hits and performed flawlessly, successfully going into orbit around Saturn on June 30. The engine burn for entering orbit went so well that mission managers have decided to forgo an orbital-adjustment maneuver scheduled for today.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.

For the latest images and more information about the Cassini-Huygens mission, visit and

Original Source: NASA/JPL News Release

Post your Astro Photos

I’ve added a new section to the forum called “Astrophotography”. Unlike all the other sections of the forum, this one allows you to upload files to the server so you can post your pictures and share them with other members. If you’ve taken some great pictures with your telescope and camera, please post them here. Please include any technical information as well about your equipment, exposure times, software, etc., so we can all learn and improve our space photos.

Click here to access the “Astrophotography” section of the forum. As always, if you have any problems accessing the forum, setting up an account, or posting your photographs, please drop me an email and I’d be happy to help you out. Thanks to seeker372011 for getting things rolling. 🙂

Fraser Cain
Universe Today