Archive picture of a Proton launch. Image credit: ILS
It appears that the Russian government wants to take action over the string of unmanned mission failures beleaguering Roscosmos, or the Russian Federal Space Agency. A recent example includes the loss in June of three GLONASS navigation/positioning satellites in a launch failure. In 2011, Roscosmos lost four major missions, including the Phobos-Grunt spacecraft that was bound for the Martian moon Phobos.
RIA Novosti reports that Dmitry Rogozin, Russia’s deputy prime minister, plans to create a new state entity to take over space manufacturing. The proposed United Rocket and Space Corporation, the report says, will reduce the reliance on imported parts to get missions off the ground, among other aims.
“A new state corporation will be created to take over manufacturing facilities from the Federal Space Agency, whose prestige has been severely dented in recent years by a string of failed rocket launches,” the report says. “The proposed United Rocket and Space Corporation will enable the trimming away of redundant departments replicated elsewhere in the space industry.”
As for Roscosmos itself, the report hints that other changes could be on the way. Its envisioned role is to “act as a federal executive body and contracting authority for programs to be implemented by the industry.” There are expected to be changes in management, among other measures.
The agency was formed after the breakup of the Soviet Union in 1991 and is responsible for most of Russia’s space activities. Russia’s heritage in space actually stretches back to the dawn of the space age in the 1950s and 1960s, when the country became the first nation to launch a satellite (Sputnik) and a human (Yuri Gagarin), among other milestones.
I finally caught up with the rest of the space journalist community and watched the new Gravity movie last night.
I absolutely loved it. It was by far the best movie I’ve seen this year, and I think one of the best space movies ever made.
The attention to detail on so many aspects of spaceflight was heartening: the cramped conditions of the space station, the perspective of the Earth, the lack of sound, the realistic physics (mostly).
WARNING – Spoilers Ahead
I believe that good art benefits from constraints. And in this case, director Alfonso Cuarón gave himself the constraint of a realistic portrayal of space, and it paid off in so many ways.
Except when he didn’t. There are a pile of unscientific moments that happen in the movie, that I think could have been easily fixed in the script stage.
It would have been amazing to hear Phil Plait or Neil deGrasse Tyson scratching their heads, unable to find a single scientific flaw.
So let’s fix Gravity
I’ll go first.
Remember I said spoilers? Here come the spoilers.
Stone can’t hold on to Kowalski and he’s forced to detach himself – As it was portrayed in the movie, and noted by Phil, he had no force pulling him away from Stone, so she should have been able to easily tug him back. But if the station was rotating quickly enough, there would be outward centripetal force.
People have speculated on the internet that it was rotating, and the background stars are shifting. But if that was the case, loose ropes and cables would be extending out from the station. And things wouldn’t have been floating so freely inside the station.
Solution:
As the astronauts are approaching the ISS, they noticed that the first Soyuz had already been used to abandon the station – what if they gave the station a kick as they departed in a rush? So maybe Kowalski could have noticed that the station was spinning. And the mess of parachute lines would have been taut, reflecting that.
That would have made hanging onto the lines more difficult, and would have been enough force to tear Kowalski away.
Your turn. What was a problem in the story, and how could it have been fixed without seriously ruining the movie?
I posted this topic over on Google+ and got some great suggestions for topics:
How could you get a debris cascade going so quickly?
Shouldn’t airlocks open inward?
Why did a fire start at the exact moment Stone gets on board ISS?
How could you get from Hubble to ISS to Tiangong? They’re on different orbital trajectories?
Why would communications satellites get taken out? They’re at a much higher altitude.
Why wasn’t Stone wearing traditional astronaut undergarments and, uh, a diaper?
Why didn’t Stone’s hair float in microgravity?
What scientific inconsistencies did you see, and how would you fix them?
An artist's conception of two magnetic fields interacting in a bow shock. Image credit: NASA
Astronomers may soon be able to observe the shockwaves between the magnetic fields of exoplanets and the flow of particles from the stars they orbit.
Magnetic fields are crucial to a planet’s (and as it turns out a moon’s) habitability. They act as protective bubbles, preventing harmful space radiation from stripping away the object’s atmosphere entirely and even reaching the surface.
An extended magnetic field – known as a planetary magnetosphere – is created by the shock between the stellar wind and the intrinsic magnetic field of the planet. It has the potential to be huge. Within our own Solar System, Jupiter’s magnetosphere extends to distances up to 50 times the size of the planet itself, nearly reaching Saturn’s orbit.
When the wind of high-energy particles from the star hits the planetary magnetosphere, it interacts in a bow shock that diverts the wind and compresses the magnetosphere.
Recently a team of astronomers, led by PhD student Joe Llama of the University of St. Andrews, Scotland, have worked out how we might observe planetary magnetospheres and stellar winds via their bow shocks.
Llama took a careful look at the planet HD 189733b, located 63 light years away toward the constellation Vulpecula. From the Earth, the planet is seen to transit its host star every 2.2 days, causing a dip in the overall light from the system.
As a bright star, HD 189733b has been studied extensively by astronomers. Data collected in July 2008 by the Canada-France-Hawaii telescope mapped the star’s magnetic field. While the magnetic field varied, it was on average 30 times greater than that of our Sun – meaning that the stellar wind is much higher than the solar wind.
This allowed the team to carry out extensive simulations of the stellar wind around HD 189733b – characterizing the bow shock created as the planet’s magnetosphere passes through the stellar wind. With this information they were able to simulate the light curves that would result from the planet and the bow shock orbiting the star.
The bow shock leads the planet – causing the light to drop a little earlier than expected. The amount of light blocked by the bow shock, however, will change as the planet moves through a variable stellar wind. If the stellar wind is particularly strong, the resulting bow shock will be strong, and the transit depth will be greater. If the stellar wind is weak, the resulting bow shock will be weak, and the transit depth will be less.
The video below shows the light curve of a bow shock and exoplanet.
“We found that the shockwave between the stellar and planetary magnetic fields will change drastically as activity on the star varies,” Llama told Universe Today. “As the planet passes through very dense regions of the stellar wind, so the shock will become denser, the material in it will block more light and therefore cause a larger dip in the transit making it more detectable.”
While there were no transit observations for this study, this theoretical outlook demonstrates that it will be possible to detect the bow shock, and therefore the magnetic field, of a distant exoplanet. Dr. Llama comments: “This will help us to better identify potentially habitable worlds.”
The paper has been accepted for publication in Monthly Notices of The Royal Astronomical Society and is available for download here.
Artist's conception of Juno coming near Earth on a planned flyby Oct. 9, 2013. Credit: NASA
Every so often, engineers send a spacecraft in Earth’s general direction to pick up a speed boost before heading elsewhere. But sometimes, something strange happens — the spacecraft’s speed varies in an unexpected way. Even stranger, this variation happens only during some Earth flybys.
“We detected the flyby anomaly during Rosetta’s first Earth visit in March 2005,” stated Trevor Morley, a flight dynamics specialist at the European Space Agency’s European Space Operations Centre in Darmstadt, Germany.
“Frustratingly, no anomaly was seen during Rosetta’s subsequent Earth flybys in 2007 and 2011. This is a real cosmic mystery that no one has yet figured out.”
The phenomenon has been noticed in several spacecraft (both from ESA and NASA) since 1990. NASA’s NEAR asteroid spacecraft in January 1998 had the largest change, of 13 millimeters (0.5 inches) a second. The smallest variations, with NASA’s Saturn-bound Cassini in 1999 and Mercury-pointing MESSENGER in 2005, were below the threshold of measurement.
ESA won’t even speculate on what’s going on. “The experts are stumped,” the agency says in a press release.
Those experts, however, do have some ideas on how to track that down. ESOC plans to watch Juno’s flyby using a 35 meter deep-space dish in Malargüe, Argentina, as well as a 15-meter dish in Perth, Australia
“The stations will record highly precise radio-signal information that will indicate whether Juno speeds up or slows down more or less than predicted by current theories,” ESA states.
What do you think is going on? Let us know in the comments!
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
A 1909 penny being carried by the Mars Curiosity rover is caked with dust on Oct. 2, 2013, after 14 months on Mars. Credit: NASA/JPL-Caltech/MSSS/Planetary Science Institute
A high-power camera on the Mars Curiosity rover snapped a picture of a 1909 American penny featuring Abraham Lincoln. The coin is used as a calibration target for the Mars Hand Lens Imager (MAHLI) that is at the end of Curiosity’s robotic arm. In just over an Earth year on the Red Planet, you can see the bright copper is muted by lots of Mars dust.
Although the image has public relations appeal, there are scientific reasons behind picking that particular calibration target. It is supposed to measure how well the camera is performing, which is important as it zooms in on interesting features on Mars.
“The image shows that, during the penny’s 14 months (so far) on Mars, it has accumulated Martian dust and clumps of dust, despite its vertical mounting position,” the Planetary Science Institute stated.
Curiosity’s calibration target, shown before launch. Two instruments at the end of the robotic arm on NASA’s Mars rover Curiosity use the calibration targets attached to a shoulder joint of the arm. Credit: NASA/JPL-Caltech
“At 14 micrometers per pixel, this is the highest resolution image that the MAHLI can acquire,” the statement added.
“This image was obtained as part of a test; it was the first time that the rover’s robotic arm placed the MAHLI close enough to a target to obtain MAHLI’s highest-possible resolution. The previous highest-resolution MAHLI images, which were pictures of Martian rocks, were at 16-17 micrometers per pixel. A micrometer, also known as a micron, is about 0.000039 inches.”
Mauna Kea summit as seen from the northeast. Credit: University of Hawaii.
An astronomy student at Mauna Kea Observatories in Hawaii took some time off from his work to share the experience of being on the summit, gazing at the telescopes. The result is a nearly three-minute long time lapse video that makes you feel like you’re standing right next to those observatories.
Watching the telescopes move by day is mesmerizing enough, but stick around a few seconds and then you will see galaxies, stars and other cosmic sights pop into view — right behind the observatories that are looking at the same things.
“This montage was filmed on three nights in April (I was observing on one of the telescopes and would walk outside when things got boring) and four nights during summer 2013,” wrote Sean Goebel on the Vimeo page hosting the video. You can check out more of his timelapse photography at this website.
Trajectory Map of Juno’s Earth Flyby on Oct. 9, 2013. The Earth gravity assist is required to accelerate Juno’s arrival at Jupiter on July 4, 2016 and will captured unprecedented movie of Earth/Moon system. Credit: NASA/JPL
Trajectory Map of Juno’s Earth Flyby on Oct. 9, 2013
The Earth gravity assist is required to accelerate Juno’s arrival at Jupiter on July 4, 2016 and will capture an unprecedented movie of the Earth/Moon system. Credit: NASA/JPL
Details on how to watch via Slooh – see below [/caption]
NASA’s solar powered Jupiter-bound Juno orbiter is careening towards Earth for an absolutely critical gravity assisted fly by speed boost while capturing an unprecedented movie view of the Earth/Moon system – on its ultimate quest to unveiling Jupiter’s genesis!
“Juno will flyby Earth on October 9 to get a gravity boost and increase its speed in orbit around the Sun so that it can reach Jupiter on July 4, 2016,” Juno chief scientist Dr. Scott Bolton told Universe Today in an exclusive new Juno mission update – as the clock is ticking to zero hour. “The closest approach is over South Africa.”
All this ‘high frontier’ action comes amidst the utterly chaotic US government partial shutdown, that threatened the launch of the MAVEN Mars orbiter, has halted activity on many other NASA projects and stopped public announcements of the safe arrival of NASA’s LADEE lunar orbiter on Oct. 6, Juno’s flyby and virtually everything else related to NASA!
Bolton confirmed that the shutdown fortunately hasn’t altered or killed Juno’s flyby objectives. And ops teams at prime contractor Lockheed Martin have rehearsed and all set.
And some more good news is that Slooh will track the Juno Earth Flyby “LIVE” – for those hoping to follow along. Complete details below!
“The shutdown hasn’t affected our operations or plans, Bolton told me. Bolton is Juno’s principal investigator from the Southwest Research Institute (SwRI), San Antonio, Texas.
“Juno is 100% healthy.”
“But NASA is unable to participate in our public affairs and press activities,” Bolton elaborated.
NASA’s Juno Jupiter-bound space probe will fly by Earth for essential speed boost on Oct 9, 2013. Credit: NASA/JPL
97% of NASA’s employees are furloughed – including public affairs – due to the legal requirements of the shutdown!
Credit: NASA/JPLJuno will also capture an unprecedented new movie of the Earth/Moon system.
A full up science investigation of our Home Planet by Juno is planned, that will also serve as a key test of the spacecraft and its bevy of state of the art instruments.
“During the earth flyby we have most of our instruments on and will obtain a unique movie of the Earth Moon system on our approach.
“We will also calibrate instuments and measure earth’s magnetosphere, obtain closeup images of the Earth and the Moon in UV [ultraviolet] and IR [infrared],” Bolton explained to Universe Today.
The flyby will accelerate the spacecraft’s velocity by 16,330 mph.
Where is the best view of Juno’s flyby, I asked?
“The closest approach is over South Africa and is about 500 kilometers [350 miles],” Bolton replied.
The time of closest approach is 3:21 p.m. EDT (12:21 PDT / 19:21 UTC) on Oct. 9, 2013
Watch this mission produced video about Juno and the Earth flyby:
Video caption: On Oct. 9, 2013, NASA’s Jupiter-bound Juno spacecraft is making a quick pass to get a gravity boost from the mother planet. Dr. Scott Bolton of Southwest Research Institute® is the Juno mission principal investigator, leading an international science team seeking to answer some fundamental questions about the gas giant and, in turn, about the processes that led to formation of our solar system.
NASA’s Juno spacecraft blasted off atop an Atlas V rocket two years ago from Cape Canaveral Air Force Station, FL, on Aug. 5, 2011 to begin a 2.8 billion kilometer science trek to discover the genesis of Jupiter hidden deep inside the planet’s interior.
Juno is on a 5 year and 1.7 Billion mile (2.8 Billion km) trek to the largest planet in our solar system. When it arrives at Jupiter on July 4, 2016, Juno will become the first polar orbiting spacecraft at the gas giant.
During a one year science mission – entailing 33 orbits lasting 11 days each – the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s genesis and evolution.
The goal is to find out more about the planets origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core
Why does Juno need a speed boost from Earth?
“A direct mission to Jupiter would have required about 50 percent more fuel than we loaded,” said Tim Gasparrini, Juno program manager for Lockheed Martin Space Systems, in a statement.
“Had we not chosen to do the flyby, the mission would have required a bigger launch vehicle, a larger spacecraft and would have been more expensive.”
Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
Viewers near Cape Town, South Africa will have the best opportunity to view the spacecraft traveling across the sky.
Juno itself will most likely not be visible to the unaided eye, but binoculars or a small telescope with a wide field should provide an opportunity to view, according to a Slooh statement.
Slooh will track Juno live on October 9th, 2013.
Check here for international starting times: http://goo.gl/7ducFs – and for the Slooh broadcast hosted by Paul Cox.
Viewers can view the event live on Slooh.com using their computer or mobile device, or by downloading the free Slooh iPad app in the iTunes store. Questions can be asked during the broadcast via Twitter by using the hashtag #nasajuno -says Slooh.
Amidst the government shutdown, Juno prime contractor Lockheed Martin is working diligently to ensure the mission success.
Because there are NO 2nd chances!
“The team is 100 percent focused on executing the Earth flyby successfully,” said Gasparrini.
“We’ve spent a lot of time looking at possible off-nominal conditions. In the presence of a fault, the spacecraft will stay healthy and will perform as planned.”
Stay tuned here for continuing Juno, LADEE, MAVEN and more up-to-date NASA news.
And be sure to check back here for my post-flyby update.
What’s not at all clear is whether Juno will detect any signs of ‘intelligent life’ in Washington D.C.!
Learn more about Juno, LADEE, MAVEN, Curiosity, Mars rovers, Cygnus, Antares, SpaceX, Orion, the Gov’t shutdown and more at Ken’s upcoming presentations
Oct 8: “NASA’s Historic LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”& “Curiosity, MAVEN, Juno and Orion updates”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM
Neptune's system of moons and rings visualized. Credit: SETI
“That’s no moon…”
-B. Kenobi
But in this case, it is… a lost moon of Neptune not seen since its discovery in the late 1980’s.
A new announcement from the 45th Meeting of the Division for Planetary Sciences of the American Astronomical Society being held this week in Denver, Colorado revealed the recovery of a moon of Neptune that was only briefly glimpsed during the 1989 flyby of Voyager 2.
The re-discovery Naiad, the innermost moon of Neptune, was done by applying new processing techniques to archival Hubble images and was announced today by Mark Showalter of the SETI institute.
Collaborators on the project included Robert French, also from the SETI Institute, Dr. Imke de Pater of UC Berkeley, and Dr. Jack Lissauer of the NASA Ames Research Center.
The findings were a tour-de-force of new techniques applied to old imagery, and combined the ground-based 10 meter Keck telescope in Hawaii as well as Hubble imagery stretching back to December 2004.
The chief difficulty in recovering the diminutive moon was its relative faintness and proximity to the “dazzling” disk of Neptune. At roughly 100 kilometres in diameter and an apparent magnitude of +23.9, Naiad is over a million times fainter than +8th magnitude Neptune. It’s also the innermost of Neptune’s 14 known moons, and orbits once every 7 hours just 23,500 kilometres above the planet’s cloud tops. Neptune itself is about 49,000 kilometres in diameter, and only appears 2.3” in size from Earth. From our Earthly vantage point, Naiad only strays about arc second from the disk of Neptune, a tiny separation.
“Naiad has been an elusive target ever since Voyager left the Neptune system,” Showalter said in a recent SETI Institute press release. Voyager 2 has, to date, been the only mission to explore Uranus and Neptune.
To catch sight of the elusive inner moon, Showalter and team applied new analyzing techniques which filtered for glare and image artifacts that tend to “spill over” from behind the artificially occulted disk of Neptune.
Other moons, such as Galatea and Thalassa — which were also discovered during the 1989 Voyager 2 flyby — are also seen in the new images. In fact, the technique was also used to uncover the as of yet unnamed moon of Neptune, S/2004 N1 which was revealed earlier this year.
Naiad is named after the band of nymphs in Greek mythology who inhabited freshwater streams and ponds. The Naiads differed from the saltwater-loving Nereids of mythology fame, after which another moon of Neptune discovered by Gerard Kuiper in 1949 was named.
It’s also intriguing to note that Naiad was discovered in a significantly different position in its orbit than expected. Clearly, its motion is complex due to its interactions with Neptune’s other moons.
“We don’t quite have enough observations to establish a refined orbit,” Mr. Showalter told Universe Today, noting that there may still be some tantalizing clues waiting to be uncovered from the data.
I know the burning question you have, and we had as well during the initial announcement today. Is it REALLY Naiad, or another unknown moon? Showalter notes that this possibility is unlikely, as both objects seen in the Hubble and Voyager data are the same brightness and moving in the same orbit. To invoke Occam’s razor, the simplest solution— that both sightings are one in the same object —is the most likely.
“Naiad is well inside Neptune’s Roche Limit, like many moons in the solar system,” Mr. Showalter also told Universe Today. Naiad is also well below synchronous orbit, and is likely subject to tidal deceleration and may one day become a shiny new ring about the planet.
The labeled ring arcs of Neptune as seen in newly processed data. The image spans 26 exposures combined into an equivalent 95 minute exposure. The ring trace and an image of the occulted planet Neptune is added for reference. (Credit: M. Showalter/SETI Institute).
And speaking of which, the tenuous rings of Neptune have also evolved noticeably since the 1989 Voyager flyby. First discovered from the ESO La Silla Observatory in 1984, data using the new techniques show that the knotted ring segments named the Adams and Le Verrier have been fading noticeably.
“In a decade or two, we may see an ‘arc-less’ ring,” Showalter noted during today’s Division for Planetary Sciences press conference. The two ring segments observed are named after Urbain Le Verrier and John Couch Adams, who both calculated the position of Neptune due to orbital perturbations of the position of Uranus. Le Verrier beat Adams to the punch, and Neptune was first sighted from the Berlin Observatory on the night of September 23rd, 1846. Observers of the day were lucky that both planets had undergone a close passage just decades prior, or Neptune may have gone unnoticed for considerably longer.
The rings of Neptune as seen from Voyager 2 during the 1989 flyby. (Credit: NASA/JPL).
Neptune has completed just over one 164.8 year orbit since its discovery. It also just passed opposition this summer, and is currently a fine telescopic object in the constellation Aquarius.
Unfortunately, there aren’t any plans for a dedicated Neptune mission in the future. New Horizons will cross the orbit of Neptune in August 2014, though it’s headed in the direction of Pluto, which is currently in northern Sagittarius. New Horizons was launched in early 2006, which gives you some idea of just how long a “Neptune Orbiter” would take to reach the outermost ice giant, given today’s technology.
This represents the first time that Naiad has been imaged from the vicinity of Earth, and demonstrates a new processing technique capable of revealing new objects in old Hubble data.
“We keep discovering new ways to push the limit of what information can be gleaned from Hubble’s vast collection of planetary images,” Showalter said in the SETI press release.
Congrats to Showalter and team on the exciting recovery… what other moons, both old and new, lurk in the archives waiting to be uncovered?
– Read today’s SETI Institute press release on the recovery of Naiad.
-Be sure to follow all the action at the 45th DPS conference in Denver this week!
Jupiter with polka dot shadows cast by Io, Europa and Callisto as depicted around 1 a.m. EDT Oct. 12. Watch for the Great Red Spot to come into view during the transit. Created with Claude Duplessis' Meridian software
Talk about a great fall lineup. Three of Jupiter’s four brightest moons plan a rare show for telescopic observers on Friday night – Saturday morning Oct. 11-12. For a span of just over an hour, Io, Europa and Callisto will simultaneously cast shadows on the planet’s cloud tops, an event that hasn’t happened since March 28, 2004.
Who doesn’t remember their first time looking at Jupiter and his entourage of dancing moons in a telescope? Because each moves at a different rate depending on its distance from the planet, they’re constantly on the move like kids in a game of musical chairs. Every night offers a different arrangement.
Jupiter and its four brightest moons seen in a small telescope. Credit: Bob King
Some nights all four of the brightest are strung out on one side of the planet, other nights only two or three are visible, the others hidden behind Jupiter’s “plus-sized” globe. Occasionally you’ll be lucky enough to catch the shadow of one of moons as it transits or crosses in front of the planet. We call the event a shadow transit, but to someone watching from Jupiter, the moon glides in front of the sun to create a total solar eclipse.
Since the sun is only 1/5 as large from Jupiter as seen from Earth, all four moons are large enough to completely cover the sun and cast inky shadows. To the eye they look like tiny black dots of varying sizes. Europa, the smallest, mimics a pinprick. The shadows of Io and Callisto are more substantial. Ganymede, the solar system’s largest moon at 3,269 miles (5,262 km), looks positively plump compared to the others. Even a small telescope magnifying around 50x will show it.
Jupiter on Sept. 24 with its moon Europa (at left) casting a pinhead black shadow on Jupiter’s clouds. Credit: John Chumack
The three inner satellites – Io, Europa and Ganymede – have shadow transits every orbit. Distant Callisto only transits when Jupiter’s tilt relative to Earth is very small, i.e. the plane of the planet’s moons is nearly edge-on from our perspective. Callisto transits occur in alternating “seasons” lasting about 3 years apiece. Three years of shadow play are followed by three years of shadowless misses. Single transits are fairly common; you can find tables of them online like this one from Project Pluto or plug in time and date into a free program like Meridian for a picture and list of times.
Because Io, Europa and Ganymede orbit in a 4:2:1 resonance (Io revolves four times around Jupiter in the time it takes Ganymede to orbit once; Europa completes two orbits for Ganymede’s one) it’s impossible for all three to line up – along with Callsto – for a “quadruple transit”. Credit: Matma Rex / Wikipedia
Seeing two shadows inch across Jupiter’s face is very uncommon, and three are as rare as a good hair day for Donald Trump. Averaged out, triple transits occur once or twice a decade. Friday night Oct. 11 each moon enters like actors in a play. Callisto appears first at 11:12 p.m. EDT followed by Europa and then Io. By 12:32 a.m. all three are in place.
Catch them while you can. Groups like these don’t last long. A little more than an hour later Callisto departs, leaving just two shadows. You’ll find the details below. All times are Eastern Daylight or EDT. Subtract one hour for Central time and add four hours for BST (British Summer Time):
* Callisto’s shadow enters the disk – 11:12 p.m. Oct. 11
* Europa – 11:24 p.m.
* Io – 12:32 a.m. ** TRIPLE TRANSIT from 12:32 – 1:37 a.m.
* Callisto departs – 1:37 a.m.
* Europa departs – 2:01 a.m.
* Io departs – 2:44 a.m.
Looking at Jupiter from high above the plane of the solar system in this diagram from more than a century ago, we can better picture how shadow transits and eclipses happen. The tiny disk of Io and the shadow of Ganymede are seen in transit; Callisto is about to be eclipsed by Jupiter’s shadow. Credit: Garrett Serviss from “Pleasures of the Telescope” (annotations: Bob King)
The triple transit will be seen across the eastern half of the U.S., Europe and western Africa. Those living on the East Coast have the best view in the U.S. with Jupiter some 20-25 degrees high in the northeastern sky around 1 a.m. local time. Things get dicier in the Midwest where Jupiter climbs to only 5-10 degrees. From the mountain states the planet won’t rise until Callisto’s shadow has left the disk, leaving a two-shadow consolation prize. If you live in the Pacific time zone and points farther west, you’ll unfortunately miss the event altogether.
From the Eastern Time Zone Jupiter will be well-placed in the eastern sky during the transit. Created with Stellarium
Key to seeing all three shadows clearly, especially if Jupiter is low in the sky, is steady air or what skywatchers call “good seeing”. The sky can be so clear you’d swear there’s a million stars up there, but a look through the telescope will sometimes show dancing, blurry images due to invisible air turbulence. That’s “bad seeing”. Unfortunately, bad seeing is more common near the horizon where we peer through a greater thickness of atmosphere. But don’t let that keep you inside Friday night. With a spell of steady air, all you need is a 4-inch or larger telescope magnifying around 100x to spot all three.
The March 28, 2004 triple transit. Shadows from left: Ganymede, Io and Callisto. You can also see the disks of Io (white dot) and Ganymede (blue dot) in this photo taken in infrared light by the Hubble Space Telescope. Credit: NASA/ESA
If bad weather blocks the view, there are two more triple transits coming up soon – a 95-minute-long event on June 3, 2014 starring Europa, Ganymede and Callisto (not visible in the Americas) and a 25-minute show on Jan. 24, 2015 featuring Io, Europa and Callisto and visible across Western Europe and the Americas. That’s it until dual triple transits in 2032.
