Wow! Check out this video of the Moon passing in front of Saturn from a viewpoint in Brisbane, Australia. This type of phenomenon, called an occultation, happens when one celestial body passes in front of the other from an observer’s standpoint. You can see some information about a June 10 occultation of Saturn, for example, at this link.
“There has been a fair amount of post-processing done on the images to get to this result. The first stage was to adjust the source images so that detail was visible both on Saturn and on the Moon. This is because the two objects are quite different in brightness, and so each individual exposure results in a slightly over-exposed Moon and a slightly under-exposed Saturn,” wrote Teale Britstra, who created the video, on Vimeo.
“After initial processing, the series of images were imported into video editing software, and the resulting footage stabilized to eliminate some small tracking errors between shots,” Britstra continued.
“There was also one LARGE tracking error, where I had to physically move the telescope. This was because the Moon was sinking towards the western horizon and some nearby, large trees which would have obscured the shot had the scope not been moved. This can be seen in the resulting footage as the period where the Moon appears to slow down and slightly change direction.”
A stream of gas 2.6 million light-years long stretches in green across this picture. The insets are of galaxies in the neighborhood, while the green circle represents the Arecibo telescope beam. Credit: Rhys Taylor/Arecibo Galaxy Environment Survey/The Sloan Digital Sky Survey Collaboration
How the heck did all that gas get there? Researchers have discovered an astonishing amount of it bridging galaxies, stretching across a stream that is 2.6 million light-years across. This is more than a million light-years longer than a similar stream that was previously found in the Virgo Cluster.
“This was totally unexpected,” stated Rhys Taylor, a researcher at the Czech Academy of Sciences who led the research. “We frequently see gas streams in galaxy clusters, where there are lots of galaxies close together, but to find something this long and not in a cluster is unprecedented.”
The atomic hydrogen gas is about 500 million light-years away and was spotted with the William E. Gordon Telescope at the Arecibo Observatory in Puerto Rico.
Its origins are unknown, but one hypothesis postulateas that a larger galaxy passed close to smaller galaxies in the distant past, drawing out the gas as the larger galaxy moved apart again. Alternately, the large galaxy could have pushed through the group and disturbed the gas within it.
The research will be published shortly in the Monthly Notices of the Royal Astronomical Society.
Artist's conception of "spacecraft/rover hybrids for the exploration of small solar system bodies", a concept funded under Phase II of NASA' Innovative Advanced Concepts program in 2014. Credit: NASA
How do crazy but neat ideas such as the Mars crane make it to space? It’s through years, sometimes decades, of development to try to solve a problem in space exploration. NASA has an entire program devoted to far-out concepts that are at least a decade from making it into space, and has just selected five projects for a second round of funding.
One of them is a robotic swarm of spacecraft that we’ve written about before on Universe Today. Flying out from a mothership, these tiny spacecraft would be able to tumble across the surface of a low-gravity moon or asteroid.
“The systematic exploration of small bodies would help unravel the origin of the solar system and its early evolution, as well as assess their astrobiological relevance,” stated its principal investigator, Stanford University’s Marco Pavone, in a 2012 story. “In addition, we can evaluate the resource potential of small bodies in view of future human missions beyond Earth.”
The concept, called “Spacecraft/Rover Hybrids for the Exploration of Small Solar System Bodies“, is among the selectees in the second phase of the NASA Innovative Advanced Concepts program. Each will receive up to $500,000 to further develop their concept during the next two years. While Phase I studies are considered to show if a project is feasible, Phase II begins to narrow down the design.
Artist’s conception of a 10-meter sub-orbital large balloon reflector funded under NASA’s Innovative Advanced Concepts program. Credit: NASA
“This was an extremely competitive year for NIAC Phase II candidates,” stated Jay Falker, the program’s executive at NASA Headquarters. “But the independent peer review process helped identify those that could be the most transformative, with outstanding potential for future science and exploration.”
This is the rest of the selected concepts:
10 meter Sub-Orbital Large Balloon Reflector (Christopher Walker, University of Arizona): A telescope that uses part of a balloon as a reflector. The telescope would fly high in the atmosphere, perhaps doing examinations of Earth’s atmosphere or performing telecommunications or surveillance.
Low-Mass Planar Photonic Imaging Sensor(Ben S.J. Yoo, University of California, Davis): A new way of thinking about telescopes that would use a low-mass planar photonic imaging sensor. This could be useful for missions to the outer solar system.
Orbiting Rainbows (Marco Quadrelli, NASA Jet Propulsion Laboratory): Using “an orbiting cloud of dust-like matter” for astronomical imaging by taking advantage of the spots where light passes through.
The white X at the top of the image marks the location of the supernova. The inset panel is a pair of Hubble Space Telescope images of the spiral galaxy NGC 1309 that were taken before and after the appearance of Supernova 2012Z. Credit: NASA, ESA, C. McCully and S. Jha (Rutgers University), R. Foley (University of Illinois), and Z. Levay (STScI)
More than two decades of Hubble observations have produced more than 25 terabytes of data. Thanks to the wealth of information stored in the Hubble data archive, astronomers can easily revisit old images in an effort to better understand new discoveries.
Now, astronomers have used the archive to find the progenitor of a mysterious type of supernova, dubbed Type 1ax, which is less energetic and much fainter than its Type Ia cousin.
A Type 1a supernova occurs when a white dwarf siphons material off a companion star, building an additional layer of hydrogen on its surface that will eventually trigger a runaway reaction that detonates the accumulated gas.
The most popular explanation for Type 1ax supernovae is that they’re created in the same way, except the explosion doesn’t completely tear the white dwarf into pieces. Instead, the white dwarf ejects roughly half of its mass. It becomes battered and bruised, leaving behind a hot core composed of carbon and oxygen.
So far, astronomers have identified more than 30 of these mini-explosions, which occur at one-fifth the rate of Type 1a supernovae.
“Astronomers have been searching for decades for the progenitors of Type Ia’s,” said Saurabh Jha from Rutgers University in a NASA press release. “Type Ia’s are important because they’re used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes. The similarities between Type Iax’s and normal Type Ia’s make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified.”
So after the team observed the weak supernova, dubbed SN 2012Z, in the Lick Observatory Supernova Search, they dug through Hubble’s archive. Fortuitously, Hubble had observed the supernova’s host galaxy, NGC 1309, in 2005, 2006, and 2010, before the supernova outburst.
Curtis McCully, a graduate student at Rutgers and lead author on the team’s paper, reprocessed the pre-explosion images to find an object at the supernova’s position.
“I was very surprised to see anything at the supernova’s location,” said McCully. “We expected that the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us.”
The pre-supernova observations reveal a bright, blue source the team calls S1. McCully and colleagues concluded that they were most likely seeing a star that had lost its outer hydrogen envelope, revealing its helium core. But they don’t think it’s a type of star that was about to explode, rather it’s the companion that fed the white dwarf’s outburst.
The most likely explanation involves a binary star system where each star detonates mass to the other over time.
The team acknowledges that they can’t totally rule out other possibilities for the object’s identity, including that it was simply a single, massive star that exploded as a supernova. To settle any uncertainties the team plans to use Hubble again in 2015. Hopefully by then the supernova should fade enough to get a better look at what remains.
The team’s results will appear in the journal Nature tomorrow.
Artist's conception of the Pluto system from the surface of one of its moons. Credit: NASA, ESA and G. Bacon (STScI)
When you have a spacecraft that takes the better part of a decade to get to its destination, it’s really, really important to make sure you have an accurate fix on where it’s supposed to be. That’s true of the Rosetta spacecraft (which reached its comet today) and also for New Horizons, which will make a flyby past Pluto in 2015.
To make sure New Horizons doesn’t miss its big date, astronomers are using the Atacama Large Millimeter/submillimeter Array (ALMA) to figure out its location and orbit around the Sun. You’d think that we’d know where Pluto is after decades of observations, but because it’s so far away we’ve only tracked it through one-third of its 248-year orbit.
“With these limited observational data, our knowledge of Pluto’s position could be wrong by several thousand kilometers, which compromises our ability to calculate efficient targeting maneuvers for the New Horizons spacecraft,” stated Hal Weaver, a New Horizons project scientist at Johns Hopkins University Applied Physics Laboratory in Maryland.
Pluto’s moon Charon moves around the dwarf planet in this animated image based on the data from the Atacama Large Millimeter/submillimeter Array (ALMA). Credit: B. Saxton (NRAO/AUI/NSF)
As ALMA is a radio/submillimeter telescope, the array picked up Pluto and its largest moon, Charon, by looking at the radio emission from their surfaces. They examined the objects in November 2013, in April 2014 and twice in July. More observations are expected in October.
“By taking multiple observations at different dates, we allow Earth to move along its orbit, offering different vantage points in relation to the Sun,” stated Ed Fomalont, an astronomer with the National Radio Astronomy Observatory who is assigned to ALMA’s operations support facility in Chile. “Astronomers can then better determine Pluto’s distance and orbit.”
New Horizons will reach Pluto in July 2015, and Universe Today is planning a series of articles about the dwarf planet. We’ll need your support to get it done, though. Check out the details here.
How WISE 70304-2705 could have evolved from a star to a "planet-like object". Credit: John Pinfield,
Nature once again shows us how hard it is to fit astronomical objects into categories. An examination of a so-far unique brown dwarf — an object that is a little too small to start nuclear fusion and be a star — shows that it could have been as hot as a star in the ancient past.
The object is one of a handful of brown dwarfs that are called “Y dwarfs”. This is the coolest kind of star or star-like object we know of. These objects have been observed at least as far back as 2008, although they were predicted by theory before.
A group of scientists observed the object, called WISE J0304-2705, with NASA’s space-based Wide-field Infrared Survey Explorer (WISE). Looking at the spectrum of light it had emitted, which shows the object’s composition, has scientists saying that what the brown dwarf is made of suggests it is rather old — billions of years old.
“Our measurements suggest that this Y dwarf may have a composition … or age characteristic of one of the galaxy’s older members,” stated David Pinfield at the University of Hertfordshire, who led the research.
“This would mean its temperature evolution could have been rather extreme – despite starting out at thousands of degrees, this exotic object is now barely hot enough to boil a cup of tea.”
Size comparison of stellar vs substellar objects. (Credit: NASA/JPL-Caltech/UCB).
While the object started out hot, its interior never was quite enough to fuse hydrogen. That led to the extreme cooling visible today.
Models suggest the object would have begun its life shining at 2,800 degrees Celsius (5,072 Fahrenheit), for a phase that would have lasted for 20 million years. In the next 100 million years, its temperature would have almost halved to 1,500 Celsius (2,730 Fahrenheit).
And it would have kept cooling, with a temperature of 1,000 Celsius (1,832 Fahrenheit) after a billion years, and after billions of more years, the temperature we see today — somewhere between 100 Celsius (212 Fahrenheit) and 150 Celsius (302 Fahrenheit).
The paper will be published shortly in the Monthly Notices of the Royal Astronomical Society. The research is available in preprint version on Arxiv. One limitation of the research is the small number of Y dwarfs discovered, only about 20, which means that more observations will be needed to see if other objects could have had this same evolution.
Still from a timelapse video showing the Robo-AO laser originating from the Palomar 1.5-meter Telescope dome. The laser is not visible to human eyes, but do show up in digital cameras if their UV blocking filters are removed. Credit: Institute for Astronomy, University of Hawaii / YouTube (screenshot)
There’s a group of people probing exoplanets with a laser robot, and the results are showing a few surprises. Specifically, a survey of “hot Jupiters” — the huge gas giants in tight orbits around their parent stars — shows that they are more than three times likely to be found in double star systems than other kinds of exoplanets.
The robotic laser adaptive optics system, which is installed on California’s Palomar Observatory’s 1.5-meter telescope, also discovered double star systems that each have their own planetary systems, rather than sharing one.
“We’re using Robo-AO’s extreme efficiency to survey in exquisite detail all of the candidate exoplanet host stars that have been discovered by NASA’s Kepler mission,” stated Christoph Baranec, a researcher at the University of Hawaii at Manoa’s Institute for Astronomy who led a paper on Robo-AO results.
“While Kepler has an unrivaled ability to discover exoplanets that pass between us and their host star, it comes at the price of reduced image quality, and that’s where Robo-AO excels.”
Lasers and adaptive optics are commonly used to account for changes in the atmosphere. A computer system helps the mirror change shape as the atmosphere swirls, providing clearer images for astronomers.
The Robo-AO survey cited looked at 715 candidate exoplanet systems that were first tracked down by NASA’s planet-hunting Kepler space telescope. The team is now planning to tackle the rest of the 4,000 Kepler planet candidate hosts.
Results from Robo-AO have been published in The Astrophysical Journal, here and here. You can also see a preprint version of one of these journal articles here.
Image of Io taken in the near-infrared with adaptive optics at the Gemini North telescope on August 29. In addition to the extremely bright eruption on the upper right limb of the satellite, the lava lake Loki is visible in the middle of Io’s disk, as well as the fading eruption that was detected earlier in the month by de Pater on the southern (bottom) limb. Io is about one arcsecond across. Image credit: Katherine de Kleer/UC Berkeley/Gemini Observatory/AURA
Jupiter’s innermost moon, Io — with over 400 active volcanoes, extensive lava flows and floodplains of liquid rock — is by far the most geologically active body in the Solar System. But last August, Io truly came alive with volcanism.
Three massive volcanic eruptions led astronomers to speculate that these presumed rare outbursts were much more common than previously thought. Now, an image from the Gemini Observatory captures what is one of the brightest volcanoes ever seen in our Solar System.
“We typically expect one huge outburst every one or two years, and they’re usually not this bright,” said lead author Imke de Pater from the University of California, Berkeley, in a press release. In fact, only 13 large eruptions were observed between 1978 and 2006. “Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io.”
De Pater discovered the first two eruptions on August 15, 2013, from the W. M. Keck Observatory in Hawaii. The brightest was calculated to have produced a 50 square-mile, 30-feet thick lava flow, while the other produced flows covering 120 square miles. Both were nearly gone when imaged days later.
The third and even brighter eruption was discovered on August 29, 2013, at the Gemini observatory by UC Berkeley graduate student Katherine de Kleer. It was the first of a series of observations monitoring Io.
Images of Io tracking the evolution of the eruption as it decreased in intensity over 12 days. Due to Io’s rapid rotation, a different area of the surface is viewed on each night; the outburst is visible with diminishing brightness on August 29 & 30 and September 1, 3, & 10. Image credit: Katherine de Kleer / UC Berkeley / Gemini Observatory / AURA
This allowed the observations to “represent the best day-by-day coverage of such an eruption,” said de Kleer. The team was able to conclude that the energy emitted from the late-August eruption was about 20 Terawatts, and expelled many cubic kilometers of lava.
“At the time we observed the event, an area of newly-exposed lava on the order of tens of square kilometers was visible,” said de Kleer. “We believe that it erupted in fountains from long fissures on Io’s surface, which were over ten-thousand-times more powerful than the lava fountains during the 2010 eruption of Eyjafjallajokull, Iceland, for example.”
The team hopes that monitoring Io’s surface annually will reveal the style of volcanic eruptions on the moon, the composition of the magma, and the spatial distribution of the heat flows. The eruptions may also shed light on an early Earth, when heat from the decay of radioactive elements — as opposed to the tidal forces influencing Io — created exotic, high-temperature lavas.
“We are using Io as a volcanic laboratory, where we can look back into the past of the terrestrial planets to get a better understanding of how these large eruptions took place, and how fast and how long they lasted,” said coauthor Ashley Davies.
The latest results have been published in the journal Icarus.
The July 2014 Supermoon rising over the University of Texas at Austin Tower. Credit: Mark Ezell, used with permission.
You could be forgiven for thinking this summer that the “supermoon” is now a monthly occurrence. But this coming weekend’s Full Moon is indeed (we swear) the closest to Earth for 2014.
What’s going on here? Well, as we wrote one synodic month ago — the time it takes for the Moon to return to the same phase at 29.5 days — we’re currently in a cycle of supermoons this summer. That is, a supermoon as reckoned as when the Full Moon falls within 24 hours of perigee, a much handier definition than the nebulous “falls within 90% of its orbit” proposed and popularized by astrologers.
A super-sized shot of the July 2014 supermoon. Credit: Russell Bateman.
The supermoons for 2014 fall on July 13th, August 10th and September 8th respectively. You could say that this weekend’s supermoon is act two in a three act movement, a sort of Empire Strikes Back to last month’s A New Hope.
Now for the specifics: Full Moon this weekend occurs on August 10th at 18:10 Universal Time (UT) or 2:10 PM EDT. The Moon will reach perigee or its closest point to the Earth at 17:44 UT/1:44 PM EDT just 26 minutes prior to Full, at 55.96 Earth radii distant or 356,896 kilometres away. This is just under 500 kilometres shy of the closest perigee that can occur at 356,400 kilometres distant. Perigee was closer to Full phase time-wise last year on June 23rd, 2013, but this value won’t be topped or tied again until November 25th, 2034. The Moon will be at the zenith and closest to the surface of the Earth at the moment it passes Full over the mid-Indian Ocean on Sunday evening nearing local midnight.
The 99.8% Full Moon from July 2014. Credit: Stephen Rahn.
Now for a reality check: The August lunar perigee only beats out the January 1st approach of the Moon for the closest of 2014 by a scant 25 kilometres. Perigees routinely happen whether the Moon is Full or not, and they occur once every anomalistic month, which is the average span from perigee-to-perigee at 27.6 days. This difference between the anomalistic and synodic period causes the coincidence that is the supermoon to precess forward about a month a year. You can see our list of supermoon seasons out until 2020 here.
A comparison of lunar distance (dark line) with phase (grey line) for 2014. Note that 0.5 denotes Full, while 0 denotes New phase. Credit: Darekk2, Wikimedia Commons graphic under a 3.0 Unported license.
And don’t forget, the Moon actually approaches you to the tune of about half of the radius of the Earth while it rises to the zenith, only to recede again as it sinks back down to the horizon. The rising Full Moon on the horizon only appears larger mainly due to an illusion known as the Ponzo Effect.
The apparent size of the Moon varies about 14% in angular diameter from 29.3′ (known as an apogee “mini-Moon”) to 34.1′ at its most perigee “super-size” as seen from the Earth.
The July 2014 supermoon on the rise. Credit: Brad Timerson @btimerson.
Astronomers prefer the use of the term Perigee Full Moon, but the supermoon meme has taken on a cyber-life of its own. Of course, we’ve gone on record before and stated that we prefer the more archaic term Proxigean Moon, but the supermoon seems here to stay.
And as with many Full Moon myths, this week’s supermoon will be implicated in everything from earthquakes to lost car keys to other terrestrial woes, though of course no such links exist. Coworkers/family members/strangers on Twitter will once again insist it was “the biggest ever,” and claim it took up “half the sky” as they unwittingly take part in an impromptu psychological perception test.
The July supermoon shot through a blue filter… I wonder just how rare a “Super-Blue Moon” might be? Credit: Talia Landman @taliaeliana.
Fun fact: you could ring local the horizon with 633 supermoons!
And of course, many a website will recycle their supermoon posts, though of course not here at Universe Today, as we bake our science fresh daily.
So what can you expect? Well, a perigee Full Moon can make for higher than usual tides. New York City residents had the bad fortune of a Full Moon tidal surge in 2012 when Hurricane Sandy made landfall. Though there doesn’t seem to be a chance for a repeat of such an occurrence in 2014 in the Atlantic, super-typhoon Halong is churning towards the Japanese coastline for landfall this weekend…
The rising Waxing Gibbous Moon on the evening of August 9th. Credit: Stellarium.
Observationally, Full Moon is actually a lousy time for astronomical observations, causing many a deep sky astrophotographer to instead stay home and visit the family, while lurking astrophotography forums and debunking YouTube UFO videos.
Pro-tip: want your supermoon photo/video to go viral? Shoot the rising Moon just the evening prior when it’s waxing gibbous but nearly Full. Not only will it be more likely to be picked up while everyone is focused on supermoon lunacy, but you’ll also have the added bonus of catching the Moon silhouetted against a low-contrast dusk sky. We have a pre-supermoon rising video from a few years back that still trends with each synodic period!
Well, that’s it ‘til September, when it’ll be The Return (Revenge?) of the Supermoon. Be sure to send those pics in to Universe Today’s Flickr forum, you just might make the supermoon roundup!
Comet 67P/Churyumov-Gerasimenko at 621 miles (1,000 km) on August 1. Wow! Look at that richly-textured surface. This photo has higher resolution than previous images because it was taken with Rosetta's narrow angle camera. The black spot is an artifact. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
We’re finally getting to know the icy nucleus behind comet 67P/Churyumov-Gerasimenko. For all the wonder that comets evoke, we on Earth never see directly what whips up the coma and tail. Even professional telescopes can’t burrow through the dust and vapor cloaking the nucleus to distinguish the clear outline of a comet’s heart. The only way to see one is to fly a camera there.
Asteroids we’ve seen up close show cratered surfaces similar to yet different from much of the cratering so far seen on comets. Not to scale. Credit: NASA except for Steins (ESA)
Rosetta took 10 years to reach 67P/C-G, a craggy, boot-shaped body that resembles an asteroid in appearance but with key differences. Asteroids shown in close up photos often display typical bowl-shaped impact craters. From the photos to date, 67P/C-G’s ‘craters’ look shallow and flat in comparison. Were they impacts smoothed by ice flows over time? Did some of the dust and vapor spewed by the comet settle back on the surface to partially bury and soften the landscape?
Comet 81P/Wild 2 photographed during the Stardust mission in 2004. Wild 2 measures 1.03 x 1.24 x 1.71 miles and goes around the sun once every 6.4 years. Its surfaced is riddled with flat-bottomed depressions some of which may also vent gas from vaporizing ice. Click for more 81P/Wild 2 photos. Credit: NASA
While 67P is doubtless its own comet, it does share certain similarities with Comet 81P/Wild including at least a few crater-like depressions seen during NASA’s Stardust mission. In January 2004, the spacecraft gathered photos, measurements and dust samples during its brief flyby of the nucleus. Photos reveal pinnacles, flat-bottomed depressions and bright plumes or jets of vaporizing ice.
Some of the comets we’ve seen close up through the eyes of visiting spacecraft. Credit: NASA
In a 2004 paper by Donald Brownlee and team, the group experimentally reproduced the flat-floored craters by firing projectiles into resin-coated sand baked a bit to make it cohere. Their results suggest the craters formed from impacts in loosely compacted material under the low-gravity conditions typical of small objects like comets. To quote the paper: “Most disrupted material stayed inside the cavity and formed a flat-floored deposit and steep cliffs formed the rim.” Icy materials mixed with dust may have also played a role in their appearance and other crater-like depressions called pit-halos.
Latest image of the comet taken by Rosetta’s navigation camera from a distance of only 311 miles (500 km) on August 2, 2014. The comet’s larger size in the field means fewer artifacts. Credit: ESA/Rosetta/Navcam
Speculation isn’t science, so I’ll stop here. So much more data will be streaming in soon, we’ll have our hands full. On Wednesday, August 6th, Rosetta will enter orbit around the nucleus and begin detailed studies that will continue through December 2015. Studying the new pictures now arriving daily, I’m struck by the dual nature of comets. We see an ancient landscape and yet one that looks strangely contemporary as the sun vaporizes ice, reworking the terrain like a child molding clay.
Comet 67P/Churyumov-Gerasimenko is well-placed in the mid-summer sky in Sagittarius but impossibly faint visually. Dave Herald’s photo taken on August 21, 2014 shows only a tiny fuzz of magnitude +21. Credits: Dave Herald; Stellarium
