A solar halo seen over Klerksdorp, South Africa. Credit:
Daniël Engelbrecht
Fresh off seeing a solar eclipse on Sunday, people across the southern parts of Africa witnessed another solar spectacle today, a sun halo. “It was so beautiful, everyone was taking pictures and sharing them on Facebook,” said Daniël Engelbrecht from Klerksdorp, South Africa, sending in his picture to Universe Today via email.
These halos are quite the sight to see, but unlike an eclipse, they can’t be predicted. Conditions in the atmosphere have to be just right, with moisture or ice crystals creating a “rainbow” effect around the Sun. Sometimes the halos surround the Sun completely, other times, they appear as arcs around the Sun creating what is known as sundogs. Basically, sunlight is reflecting off moisture in the atmosphere.
Ice crystals in Earth’s atmosphere can also cause rings around the Moon, and moondogs(as well as sundogs) and even Venus pillars. News reports indicate sun halos were seen just a few days ago in Africa as well, on Nov. 1, 2013.
A few other people sent in images from their phones, too of today’s sun halo:
Image of a Sun halo seen over Botswana, Southern Africa at 11:08 am local time on Nov, 6, 2013. Taken with an iPhone. Credit: Belleminah K Chitonho.Image of a Sun halo taken at 12:10 on Nov. 6, 2013, in northwest South Africa, in Mmabotho with a blackberry phone. Credit: Vanessa Lucher.
Two nascent black holes formed by the collapse of an early supergiant star. From a visualization by by Christian Reisswig (Caltech).
It’s one of the puzzles of cosmology and stellar evolution: how did supermassive black holes get so… well, supermassive… in the early Universe, when seemingly not enough time had yet passed for them to accumulate their mass through steady accretion processes alone? It takes a while to eat up a billion solar masses’ worth of matter, even with a healthy appetite and lots within gravitational reach. But yet there they are: monster black holes are common within some of the most distant galaxies, flaunting their precocious growth even as the Universe was just celebrating its one billionth birthday.
Now, recent findings by researchers at Caltech suggest that these ancient SMBs were formed by the death of certain types of primordial giant stars, exotic stellar dinosaurs that grew large and died young. During their violent collapse not just one but two black holes are formed, each gathering its own mass before eventually combining together into a single supermassive monster.
Watch a simulation and find out more about how this happens below:
To investigate the origins of young supermassive black holes, Christian Reisswig, NASA Einstein Postdoctoral Fellow in Astrophysics at Caltech and Christian Ott, assistant professor of theoretical astrophysics, turned to a model involving supermassive stars. These giant, rather exotic stars are hypothesized to have existed for just a brief time in the early Universe.
Unlike ordinary stars, supermassive stars are stabilized against gravity mostly by their own photon radiation. In a very massive star, photon radiation—the outward flux of photons that is generated due to the star’s very high interior temperatures—pushes gas from the star outward in opposition to the gravitational force that pulls the gas back in.
During its life, a supermassive star slowly cools due to energy loss through the emission of photon radiation. As the star cools, it becomes more compact, and its central density slowly increases. This process lasts for a couple of million years until the star has reached sufficient compactness for gravitational instability to set in and for the star to start collapsing gravitationally.
Previous studies predicted that when supermassive stars collapse, they maintain a spherical shape that possibly becomes flattened due to rapid rotation. This shape is called an axisymmetric configuration. Incorporating the fact that very rapidly spinning stars are prone to tiny perturbations, Reisswig and his colleagues predicted that these perturbations could cause the stars to deviate into non-axisymmetric shapes during the collapse. Such initially tiny perturbations would grow rapidly, ultimately causing the gas inside the collapsing star to clump and to form high-density fragments.
“The growth of black holes to supermassive scales in the young universe seems only possible if the ‘seed’ mass of the collapsing object was already sufficiently large.”
– Christian Reisswig, NASA Einstein Postdoctoral Fellow at Caltech
Composite image from Chandra and Hubble showing supermassive black holes in the early Universe.
These fragments would orbit the center of the star and become increasingly dense as they picked up matter during the collapse; they would also increase in temperature. And then, Reisswig says, “an interesting effect kicks in.” At sufficiently high temperatures, there would be enough energy available to match up electrons and their antiparticles, or positrons, into what are known as electron-positron pairs. The creation of electron-positron pairs would cause a loss of pressure, further accelerating the collapse; as a result, the two orbiting fragments would ultimately become so dense that a black hole could form at each clump. The pair of black holes might then spiral around one another before merging to become one large black hole.
“This is a new finding,” Reisswig says. “Nobody has ever predicted that a single collapsing star could produce a pair of black holes that then merge.”
The mineral olivine on Vesta, as seen from hyperspectral data received during the Dawn mission. Credit: Image generated by Alessandro Frigeri and Eleonora Ammannito using VIR data and Framing Camera images.
That ghoul-like sheen on the asteroid Vesta, as seen in the image above, is not some leftover of Hallowe’en. It’s evidence of the mineral olivine. Scientists have seen it before in “differentiated” bodies — those that have a crust and an inner core — but in this case, it’s turning up in an unexpected location.
Finding olivine is not that much of a surprise. Vesta is differentiated and also (likely) is the origin point of diogenite meteorites, which are sometimes olivine-rich. Researchers expected that the olivine would be close to the diogenite rocks, which in Vesta’s case are in areas of the south pole carved out from the mantle.
NASA’s Dawn mission to the asteroid did a search in areas around the south pole — “which are thought to be excavated mantle rocks”, the researchers wrote — but instead found olivine in minerals close to the surface in the northern hemisphere. These minerals are called howardites and are normally not associated with olivine. So what is going on?
Artist’s conception of the Dawn mission. Credit: NASA
Basically, it means that Vesta’s history was far more complex than we expected. This situation likely arose from a series of impacts that changed around the eucritic (stony meteorite) crust of Vesta:
“A generalized geologic history for these olivine-rich materials could be as follows: ancient large impacts excavated and incorporated large blocks of diogenite-rich and olivine-rich material into the eucritic crust, and subsequent impacts exposed this olivine-rich material,” the researchers wrote.
“This produced olivine-rich terrains in a howarditic background, with diogene-rich howardites filling nearby, eroded, older basins.”
Dawn, by the way, has completed its time at Vesta and is now en route to another large asteroid, Ceres. But there’s still plenty of data for analysis. This particular research paper was led by E. Ammannito from the Institute of Astrophysics and Space Planetology (Istituto di Astrofisica e Planetologia Spaziali) in Rome. The research appears in this week’s Nature and should be available shortly at this link.
“What’s that bright object to the southwest at dusk?” We’ve already fielded more than a few such questions as Earth’s sister world shines in the dusk sky. Venus just passed its maximum elongation 47 degrees east of the Sun on November 1st, and currently shines at a brilliant magnitude -4.46. This is almost 16 times brighter than the brightest star in the sky, -1.46th magnitude Sirius.
Venus and the waxing crescent Moon, looking to the west tonite at 30 minutes after sunset for latitude 30 degrees north. (Created using Stellarium).
Just like the Moon, Venus goes through a full range of phases. Through the telescope, Venus currently presents a 26.7” diameter disk. That size will swell to almost 40” by month’s end, as Venus begins to approach the Earth and presents a noticeable crescent phase. We just passed dichotomy — the theoretical point where Venus presents a half-illuminated phase as seen from Earth — on October 31st, and Venus already shows a noticeable crescent:
Venus on the night of November 5th 2013, a quick stack of about 200 frames. (Photo by Author)
Note that we say “theoretical” because there’s typically a discrepancy of a day or two between predicted and observed dichotomy. This is also known as Schröter’s Effect. One probable cause for this is the dazzling appearance of the disk of Venus. We typically use a variable polarizing filter to cut the glare of Venus down at the eyepiece.
You might also note that Venus currently occupies the “basement” of the zodiac in the constellation Sagittarius. In fact, the planet is currently as far south as it can go, sitting at a declination of -27° 14’ on this very evening. You have to go all the way back to 1930 to find a more southerly declination of Venus, just 12’ lower!
But you won’t have to wait much longer to break that record, as the chart below shows for the most southerly declinations of Venus for the next half century:
Year
Date
Declination
2013
November 6th
-27° 09’
2021
“ “
-27° 14’
2029
“ “
-27° 18’
2037
“ “
-27° 23’
2045
“ “
-27° 29’
2053
“ “
-27° 34’
2061
“ “
-27° 39’
Note that each event occurs on November 6th, and they’re spaced 8 years apart. Apparitions of Venus closely duplicate their paths in the sky over an 8 year cycle. This is because the planet nearly completes 13 orbits of the Sun for our 8. Venus “catches up” to the Earth on its interior orbit once every 584 days to reach inferior conjunction. It usually passes above or below the Sun from our vantage point, though last year it transited, a feat that won’t be witnessed again until 2117 AD.
How far south can Venus go? Well, its orbit is tilted 3.4 degrees relative to the ecliptic. It can reach a southern declination of -28 05’, though you have to go way back to 1874 for its last occurrence!
Today is also a great time to try your hand at spotting Venus in the daytime, as a 3-day old waxing crescent Moon lies about eight degrees to its upper right:
A daytime Venus near the Moon, transiting to the south at about 3:30PM EST today. A 5 degree wide Telrad “bullseye” is provided for scale. (Credit: Stellarium).
Note that seeing Venus in the daytime is surprisingly easy, once you known exactly where to look for it. Your best chances are around mid-afternoon at about 3PM local, when the daytime Moon and Venus lie highest in the southern sky. Did you know that Venus is actually intrinsically brighter per square arc second than the Moon? It’s true! The Moon actually has a very low reflective albedo of 12% — about the equivalent of fresh asphalt — while the cloud tops of Venus are more akin the fresh snow with an albedo of about 80%.
Its also worth checking out Venus and its local environs after nightfall as it passes near the Lagoon (M8) and the Trifid nebula (M8) on the night of November 6th. Continuing with its trek across the star rich plane of the heart of the Milky Way galaxy, Venus also passes near the globular cluster M22 on November 13th.
Venus also sits in the general of Pluto on November 15th, lying just 6.6 degrees south of it. Be sure to wave in the general direction of NASA’s New Horizons spacecraft bound for Pluto in July 2015 tonight as well, using the Moon and Venus for a guide:
The position of the Moon, Venus, Pluto, & New Horizons at 14UT on November 7th, 2013. (Created using Starry Night Education Software).
Another shot at seeing Venus paired with the Moon occurs on December 5th.
Venus also presents a maximum area of illumination on December 6th, and will shine at its brightest on December 10th at magnitude -4.7. Can you catch it casting a shadow? The best time to search for this illusive phenomenon would be just before New Moon on December 2nd. A dark sky site away from any other sources of illumination, and a snow covered ground providing high contrast also helps. Fortunately, snow isn’t in short supply in the northern hemisphere in December!
Venus is currently the only naked eye planet in the November early evening sky. We always thought that it’s a bit of a cosmic irony that the nearest planet presents a dazzling, but featureless white disk as seen from Earth. Diligent amateurs have, however, been able to tease out cloud patterns on Venus using UV filters.
Another elusive phenomenon to watch for as Venus reaches a crescent phase is ashen light. Long reported by observers, a faint glow on the night side of Venus is something that persists, but shouldn’t be. A similar effect seen on the night side of the Moon known as Earthshine is easily explained by sunlight being reflected off of the Earth… but Venus has no moon. What gives? Frequent explanations over the years have been aurorae, electrical activity, airglow, or, more frequently cited, observer bias. The brain wants to see a filled in space, and promptly inserts it betwixt the dazzling horns of the planet.
Keep an eye on Venus as it reaches maximum brilliancy and heads towards inferior conjunction on January 11th, 2014, and a rare chance to see it on said date… more to come!
Artist's conception of the Square Kilometer Array. Credit: SKA Organisation
The world’s largest radio telescope will act very much like a jigsaw; every piece of it must be precisely engineered to “fit” and to work with all the other elements. This week, the organizers of the Square Kilometer Array released which teams will be responsible for the individual “work packages” for this massive telescope, which will be in both South Africa and Australia.
“Each element of the SKA is critical to the overall success of the project, and we certainly look forward to seeing the fruits of each consortium’s hard work shape up over the coming years”, stated John Womersley, chair of the SKA board.
“Now this multi-disciplinary team of experts has three full years to come up with the best technological solutions for the final design of the telescope, so we can start tendering for construction of the first phase in 2017 as planned.”
Key science goals for SKA include the evolution of galaxies, the nature of mysterious dark energy, examining the nature of gravity and magnetism, looking at how black holes and stars are created, and even searching for extraterrestrial signals. We’ll illustrate some of those key science concepts while talking about the teams below.
This illustration shows a messy, chaotic galaxy undergoing bursts of star formation. This star formation is intense; it was known that it affects its host galaxy, but this new research shows it has an even greater effect than first thought. The winds created by these star formation processes stream out of the galaxy, ionising gas at distances of up to 650 000 light-years from the galactic centre. Credit: ESA, NASA, L. Calçada
The numbers themselves on the teams are staggering: more than 350 scientists and engineers, representing 18 countries and almost 100 institutions. There are 10 main work packages that these people are responsible for. Here they are, along with SKA’s descriptions of each element:
– Dish: “The “Dish” element includes all activities necessary to prepare for the procurement of the SKA dishes, including local monitoring & control of the individual dish in pointing and other functionality, their feeds, necessary electronics and local infrastructure.” (Led by Mark McKinnon of Australia’s Commonwealth Scientific and Industrial Research Organisation, or CSIRO.)
– Low Frequency Aperture Array: “The set of antennas, on board amplifiers and local processing required for the Aperture Array telescope of the SKA.” (Led by Jan Geralt Bij de Vaate of ASTRON, or the Netherlands Institute for Radio Astronomy).
– Mid Frequency Aperture Array: “Includes the activities necessary for the development of a set of antennas, on board amplifiers and local processing required for the Aperture Array telescope of the SKA.” (Led by de Vaate.)
Artist’s schematic impression of the distortion of spacetime by a supermassive black hole at the centre of a galaxy. The black hole will swallow dark matter at a rate which depends on its mass and on the amount of dark matter around it. Image: Felipe Esquivel Reed.
– Telescope Manager: “Will be responsible for the monitoring of the entire telescope, the engineering and operational status of its component parts.” (Led by Yashwant Gupta of the NCRA or National Centre for Radio Astrophysics in India.)
– Science Data Processor: “Will focus on the design of the computing hardware platforms, software, and algorithms needed to process science data from the correlator or non-imaging processor into science data products.” (Led by Paul Alexander of the University of Cambridge, United Kingdom.)
– Central Signal Processor: “It converts digitised astronomical signals detected by SKA receivers (antennas & dipole (“rabbit-ear”) arrays) into the vital information needed by the Science Data Processor to make detailed images of deep space astronomical phenomena that the SKA is observing.” (David Loop of the NRC, National Research Council of Canada.)
The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image.
– Signal and Data Transport: “The Signal and Data Transport (SADT) consortium is responsible for the design of three data transport networks.” (Led by Richard Schilizzi of the University of Manchester, United Kingdom.)
– Assembly, Integration & Verification: “Includes the planning for all activities at the remote sites that are necessary to incorporate the elements of the SKA into existing infrastructures, whether these be precursors or new components of the SKA.” (Led by Richard Lord of SKA South Africa.)
– Infrastructure: “Requires two consortia, each managing their respective local sites in Australia and Africa … This includes all work undertaken to deploy and be able to operate the SKA in both countries such as roads, buildings, power generation and distribution, reticulation, vehicles, cranes and specialist equipment needed for maintenance which are not included in the supply of the other elements.” (Led by Michelle Storey of CSIRO.)
– Wideband Single Pixel Feeds: “Includes the activities necessary to develop a broadband spectrum single pixel feed for the SKA.” (Led by John Conway of Chalmers University, Sweden.)
The constellation Orion photographed from orbit by Karen Nyberg (NASA)
The mighty hunter soars above the atmosphere in this photo, taken by NASA astronaut Karen Nyberg currently living and working in space aboard the ISS. One of the most recognizable constellations in night skies all across the Earth, Orion also puts on an impressive display for those well above the Earth!
Appearing here to be lying on his right side, the three stars of Orion’s famous belt — Mintaka, Alnilam, and Alnitak, top to bottom — are center frame, while his sword is nearly horizontal just to the right (the blurry center star of which isn’t a star at all, of course, but rather the enormous star-forming Orion nebula.)
Betelgeuse, as seen by the Hubble Space Telescope.
At Orion’s right shoulder is Betelgeuse, a huge red giant 20 times more massive than our Sun. Its fiery color is obvious in Karen’s photo, mirroring many of the much-closer human-made city lights visible on the ground.
In addition to featuring my favorite constellation, this photo that Karen recently shared on Twitter also serves to prove (to those few who still require evidence of such) that yes, astronauts can see stars from space. Very nicely too, I may add. The only reason they are not visible in all images is purely photographic — cameras exposing for a bright scene, like a daylit Earth (or Moon) won’t be able to capture the relatively much dimmer light of stars in the same shot, making it look like space is empty of them. Even here we can see a bit of noise in the glowing line of Earth’s atmosphere and a little blurring of edges — that’s a result of a high ISO setting to increase camera sensitivity along with a slightly longer shutter speed than your hand can easily keep stable… again, all to better capture the faint streams of photons from distant stars.
Robotic construction of the proposed "Stairway to Mars", a concept for fuelling spacecraft on their way to other destinations. Credit: Anna Nesterova art
Any road trip requires rest stops to refuel and rest. That’s especially true of planetary exploration, as it would take months between destinations. In that spirit, here is a new concept for “Mars truck stops” from the Space Development Steering Committee, which they call “Stairways to Mars.”
For those who aren’t aware, the committee is a coalition of space advocates. Included in the group are the heads of the National Space Society, the Space Frontier Foundation, and the Mars Society, SDSC said, as well as a list of past astronauts, high-ranking NASA employees and others. (The founder is Howard Bloom, who was a former visiting scholar at New York University’s graduate psychology department, among other positions.)
So how would a Mars truck stop work? In a nutshell, this is what SDSC proposes:
– Beams are constructed in space “just like a giant erector set”, according to a statement from John Strickland, SDSC chief analyst. This would be accomplished using “robots on rails” that could build the first part, then “extend … its own rails along the beam as it goes.”
– Solar panels are added on to the beam to provide power;
– Components are then added according to need. Pictures from SDSC show items such as fuel tanks on the truck stop. If ambitions soared even higher, the concept could even be built upon to make a larger space colony modelled on “O’Neill colonies”, as shown below.
A space colony under construction using a concept from the Space Development Steering Committee. The image shown above has a deck 1,000 feet wide, as well as robots that carry cargo and beams for parking spots. Credit: Anna Nesterova art
It should be emphasized that this is a concept, with no funding or firm plans yet, but for what it’s worth the committee says it could move quickly. “These plans are budgeted to cost LESS than the current NASA program for our next step in space — the $40 billion Space Launch System and Orion Capsule. What’s more, the first steps of the Stairway to Mars are achievable in three years,” the committee writes.
One possible location for this kind of truck stop would be at the Earth-Moon L1 Lagrange point, or a spot in space where gravities from different bodies approximately equal each other out and allow an object to hover in place. Lagrange points are already used for several space missions, including the Planck telescope that was just decommissioned.
What do you think of the concept? Let us know in the comments.
If you’ve ever wanted to know what 3,538 exoplanets look like spinning around their stars, here you go!
This is the third and latest installment of the mesmerizing Kepler Orrery videos by Daniel Fabrycky from the Kepler science team. It shows the relative sizes of the orbits and planets in the multi-transiting planetary systems discovered by Kepler up to November 2013 (according to the Kepler site, 3,538 candidates so far.) According to Daniel “the colors simply go by order from the star (the most colorful is the 7-planet system KOI-351). The terrestrial planets of the Solar System are shown in gray.”
The Automated Transfer Vehicle Albert Einstein burning up on Nov. 2, 2013 at 12:04 GMT over an uninhabitated part of the Pacific Ocean. This picture was snapped from the International Space Station. Credit: ESA/NASA
Flame and fireworks. That’s what the Automated Transfer Vehicle Albert Einstein appeared to astronauts to be like as it made a planned dive into Earth’s atmosphere Nov. 2. The European Space Agency ship spent five months in space, boosting the International Space Station’s altitude several times and bringing a record haul of stuff for the astronauts on board the station to use.
According to the European Space Agency, this is the first view of an ATV re-entry that astronauts have seen since Jules Verne, the first, was burned up in 2008. Controllers moved the spacecraft into view of the Expedition 37 crew to analyze the physics of breakup.
Also, yesterday you may have seen an article concerning a picture a photographer snapped of the ATV burning up on Earth. After publishing it, we then realized we were in error with that information. But it turns out the photographer actually DID capture the ATV-4 ina subsequent image. We’ve now updated the article a second time. Senior Editor Nancy Atkinson writes:
Here’s a story that we’ve updated a couple of times, and now it ultimately has a happy ending. We originally posted a picture from Oliver Broadie who thought he captured an image of the ATV-4 Albert Einstein right before it burned up in the atmosphere. That image, see below, was ultimately determined to be of the International Space Station and not the ATV-4, so yesterday we pulled the image and explained why. But now, thanks to a great discussion between the photographer and satellite tracker Marco Langbroek (see it in the comment section), they have determined that Oliver actually did capture the ATV-4 in a subsequent image taken about 4 minutes later. Thanks to both Ollie and Marco for analyzing the timing and images. Also, we were in error for saying that the image showed the ATV-4 burning up in the atmosphere. That was my mistake (Nancy).
Automated Transfer Vehicle Albert Einstein burning up in the atmosphere at 12:04 GMT on Nov. 2, 2013. Picture snapped from the International Space Station. Credit: ESA/NASA
Saturn's moons (from left to right) Janus, Pandora, Enceladus, Mimas and Rhea. Rhea is on top of Saturn. Credit: NASA/JPL-Caltech/Space Science Institute
This picture is from a couple of years ago, but still worth the extra look. The Cassini spacecraft — busily circling Saturn and gathering data on the ringed planet and its moons — managed to grab five of Saturn’s 62 known moons in one shot. The European Space Agency highlighted the picture on its home page this week.
From left to right, you can see Janus, Pandora, Enceladus, Mimas and Rhea. Don’t be fooled by the rings near Rhea; those are actually Saturn’s rings. Rhea is just blocking the view of the planet from Saturn’s perspective during this picture portrait, which was taken on July 29, 2011.
The cornucopia of moons around Saturn is part of what makes that particular planet so interesting. Titan, the largest, is perhaps the most well-known because of its strange orange haze that intrigued astronomers when the twin Voyager spacecraft zoomed through the system in the 1980s. Cassini arrived in 2004 and revealed many more moons to science for the first time.
Color-composite of Titan made from raw Cassini images acquired on April 13, 2013 (added 4/17) NASA/JPL/SSI. Composite by J. Major.
“The dozens of icy moons orbiting Saturn vary drastically in shape, size, surface age and origin. Some of these worlds have hard, rough surfaces, while others are porous bodies coated in a fine blanket of icy particles. All have greater or smaller numbers of craters, and many have ridges and valleys,” NASA wrote on a web page about Saturn’s moons.
“Some, like Dione and Tethys, show evidence of tectonic activity, where forces from within ripped apart their surfaces. Many, like Rhea and Tethys, appear to have formed billions of years ago, while others, like Janus and Epimetheus, could have originally been part of larger bodies that broke up. The study and comparison of these moons tells us a great deal about the history of the Saturn System and of the solar system at large.”
