Artist's impression of the New Horizons spacecraft. Image Credit: NASA
It’s not quite the cryogenic sleep featured in Interstellar, but all the same, NASA’s New Horizons probe has spent most of its long, long journey to Pluto in hibernation. So far it’s been asleep periodically for 1,873 days — two-thirds of its journey in space since 2006 — to save energy, money and the risk of instrument failure.
But it’s just about time for the probe to wake up. On Dec. 6, seven months before New Horizons encounters Pluto, the spacecraft will emerge from its last long nap to get ready for humanity’s first flight past the dwarf planet.
“New Horizons is healthy and cruising quietly through deep space – nearly three billion miles from home – but its rest is nearly over,” stated Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Maryland. “It’s time for New Horizons to wake up, get to work, and start making history.”
Artist’s conception of the Pluto system from the surface of one of its moons. Credit: NASA, ESA and G. Bacon (STScI)
Hibernation periods have lasted anywhere from 36 days to 202 days. Controllers usually rouse the spacecraft about twice a year to make sure all is well, and to do a little bit of science (such as taking distant pictures of Pluto of its moons). This means the next wakeup will be a new phase for the mission — a sustained effort instead of a burst of activity.
Confirmation of the wakeup should come six hours after it takes place, around 9:30 p.m. EST (2:30 p.m. UTC). This will be after the light signal takes an incredible 4.5 hours to reach Earth from New Horizons. What’s next will be a very busy few days — checking out navigation, downloading new science data, then getting the spacecraft ready for Pluto’s big closeup July 2015.
“Tops on the mission’s science list are characterizing the global geology and topography of Pluto and its large moon Charon, mapping their surface compositions and temperatures, examining Pluto’s atmospheric composition and structure, studying Pluto’s smaller moons and searching for new moons and rings,” JHUAPL stated.
Missing the planets this month? With Mars receding slowly to the west behind the Sun at dusk, the early evening sky is nearly devoid of planetary action in the month of November 2014. Stay up until about midnight local, however, and brilliant Jupiter can be seen rising to the east. Well placed for northern hemisphere viewers in the constellation Leo, Jupiter is about to become a common fixture in the late evening sky as it heads towards opposition next year in early February.
The line-up during the November 25th eclipse event (see chart below). Note that Jupiter’s moons are in 1-2-3-4 order! Credit: Stellarium.
An interesting phenomenon also reaches its climax, as we make the first of a series of passes through the ring plane of Jupiter’s moons this week on November 8th, 2014. This means that we’re currently in a season where Jupiter’s major moons not only pass in front of each other, but actually eclipse and occult one another on occasion as they cast their shadows out across space.
These types of events are challenging but tough to see, owing to the relatively tiny size of Jupiter’s moons. Followers of the giant planet are familiar with the ballet performed by the four large Jovian moons of Io, Europa, Ganymede, and Callisto. This was one of the first things that Galileo documented when he turned his crude telescope towards Jupiter in late 1609. The shadows the moons cast back on the Jovian cloud tops are a familiar sight, easily visible in a small telescope. Errors in the predictions for such passages provided 17th century Danish astronomer Ole Rømer with a way to measure the speed of light, and handy predictions of the phenomena for Jupiter’s moons can be found here.
A look at selected upcoming occultation events. Credit: Starry Night.Credit and copyright Christoper Go, used with permission.
Mutual occultations and eclipses of the Jovian moons are much tougher to see. The moons range in size from 3,121 km (Europa) to 5,262 km (Ganymede), which translates to 0.8”-1.7” in apparent diameter as seen from the Earth. This means that the moons only look like tiny +6th magnitude stars even at high magnification, though sophisticated webcam imagers such as Michael Phillips and Christopher Go have managed to actually capture disks and tease out detail on the tiny moons.
A double shadow transit from 2013. Photo by author.
What is most apparent during these mutual events is a slow but steady drop in combined magnitude, akin to that of an eclipsing variable star such as Algol. Running video, Australian astronomer David Herald has managed to document this drop during the 2009 season (see the video above) and produce an effective light curve using LiMovie.
Such events occur as we cross through the orbital planes of Jupiter’s moons. The paths of the moons do not stray more than one-half of a degree in inclination from Jupiter’s equatorial plane, which itself is tilted 3.1 degrees relative to the giant planet’s orbit. Finally, Jupiter’s orbit is tilted 1.3 degrees relative to the ecliptic. Plane crossings as seen from the Earth occur once every 5-6 years, with the last series transpiring in 2009, and the next set due to begin around 2020. Incidentally, the slight tilt described above also means that the outermost moon Callisto is the only moon that can ‘miss’ Jupiter’s shadow on in-between years. Callisto begins to so once again in July 2016.
Mutual events for the four Galilean moons come in six different flavors:
A look at the six types of phenomena possible with Jupiter’s four large moons. Created by the author.
This month, Jupiter reaches western quadrature on November 14th, meaning that Jupiter and its moons sit 90 degrees from the Sun and cast their shadows far off to the side as seen from the Earth. This margin slims as the world heads towards opposition on February 6th, 2015, and Jupiter once again joins the evening lineup of planets.
Early November sees Jupiter rising around 1:00 AM local, about six hours prior to sunrise. Jupiter is also currently well placed for northern hemisphere viewers crossing the constellation Leo.
The Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCEE) based in France maintains an extensive page following the science and the circumstances for the previous 2009 campaign and the ongoing 2015 season.
We also distilled down a table of key events for North America coming up through November and December:
A look at selected events through the end of 2014. 1=Io, 2=Europa, 3=Ganymede, 4=Callisto. O=Occultation, E=Eclipse. Created by the author, adapted from the IMCCEE chart for the 2014-15 season.
Fun fact: we also discovered during our research for this piece that these events can also produce a total solar eclipse very similar to the near perfect circumstances enjoyed on the Earth via our Moon:
Note that this season also produces another triple shadow transit on January 24th, 2015.
Observing and recording these fascinating events is as simple as running video at key times. If you’ve imaged Jupiter and its moons via our handy homemade webcam method, you also possess the means to capture and analyze the eclipses and occultations of Jupiter’s moons.
A view never seen from the Earth… Io (upper left) paired with a crescent Europa during New Horizons’ 2007 flyby. Credit: NASA/JPL.
Good luck, and let us know of your tales of astronomical tribulation and triumph!
A view of Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
Could there be an ocean hidden somewhere in that Death Star-like picture? This is an image of Mimas, a moon of Saturn, and just yesterday (Oct. 15) newly released data from the Cassini spacecraft suggests there are big liquid reservoirs underneath its surface.
“The amount of the to-and-fro motion indicates that Mimas’ interior is not uniform. These wobbles can be produced if the moon contains a weirdly shaped, rocky core or if a sub-surface ocean exists beneath its icy shell,” said Cornell University in a press release. More flybys with the Cassini spacecraft will be required to learn more about what lies beneath.
You can read more about the study (led by Cornell astronomy research associate Radwan Tajeddine) in Science, where it was published. Below, learn more about other worlds in the Solar System that could host oceans under their surface.
Enceladus
Cassini images of Saturn’s moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. This image was taken looking more or less broadside at the “tiger stripe” fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb (edge) of the moon. This image was acquired on Nov. 27, 2005. Image Credit: NASA/JPL/Space Science Institute
After nearly a decade of speculation, this year the Cassini spacecraft returned gravity data suggesting Enceladus (another moon of Saturn) does have a large subsurface ocean near its south pole, if not a global ocean. If confirmed, that could help explain why scientists see water gushing out of fractures in that area. As this recent paper by Cassini scientists shows, Enceladus is a promising location for habitability.
Titan
A halo of light surrounds Saturn’s moon Titan in this backlit picture, showing its atmosphere. Credit: NASA/JPL/Space Science Institute
By the way, anyone noticed that we still haven’t even left Saturn’s system? Titan is usually high on astrobiology wish lists for researchers because its hydrocarbon chemistry could be precursors to how life evolved. What’s not talked about as much, though, is at least two research findings pointing to evidence of a hidden ocean. Evidence comes from Titan’s tidal flexing from interacting with Saturn — which is 10 times more than what would be expected with a solid core — and the way that it moves on its own axis as well as around Saturn.
Europa
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole. Credit: NASA/ESA/L. Roth/SWRI/University of Cologne
That Minecraft-looking object floating beside Europa there is a rendering showing where water vapor erupted from the Jovian moon, spotted by the Hubble Space Telescope in 2013. We were lucky enough to have a close-up view of Europa in the 1990s and early 2000s courtesy of NASA’s Galileo spacecraft. What we know for sure is there’s thick ice on Europa. What’s underneath is not known, but there’s long been speculation that it could be a subsurface ocean that may have more water than our own planet.
Io
Jupiter’s volcanic moon Io , imaged by the Galileo spacecraft in 1997. Credit: NASA/JPL/University of Arizona
Still flying around Jupiter here, we now turn our attention to Io — a place that is often remarked upon because of its blotchy appearance as well as all of the volcanoes on its surface. A newer analysis of Galileo data in 2011 — looking at some of the lesser-understood magnetic field data signatures — led one research team to conclude there could be a magma ocean lurking underneath that violence.
Triton
A glimpse of Triton from the Voyager 2 spacecraft, which flew by the Neptunian moon in August 1989. Credit: NASA/JPL
Little is known about Triton because only one spacecraft whizzed by it — Voyager 2, which took a running pass through the Neptune system in August 1989. An Icarus paper two years ago speculated that the world could host a subsurface ocean, but more data is needed. The energy of Neptune (which captured Triton long ago) could have melted its interior through tidal heating, possibly creating water from the ice in its crust.
Charon
Hubble image of Pluto and some of its moons, Charon, Nix and Hydra. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team
We don’t have any close-up pictures of this moon of Pluto yet, but just wait a year. The New Horizons spacecraft will zoom past Charon and the rest of the system in July 2015. In the meantime, however, findings based on a model came out this summer in Icarus suggesting Charon — despite being so far from the Sun — might have had a subsurface ocean in the past. Or even now. The key is its once eccentric orbit, which would have produced tidal heating while interacting with Pluto. The science team plans to look for cracks that could be indicative of “the structure of the moon’s interior and how easily it deforms, and how its orbit evolved,” stated Alyssa Rhoden of NASA’s Goddard Space Flight Center in Maryland, who led the research.
Two potential targets for the New Horizons mission emerge in these Hubble Space Telescope multiple-exposure images. Both are about four billion miles (6.4 billion kilometers) away. NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team
Where could New Horizons visit after it flies by Pluto next year? NASA’s Hubble Space Telescope is on the case. In a program that pushed the limits of the 24-year-old observatory, Hubble found three potential Kuiper Belt Objects for the spacecraft to visit.
The wrinkle is there is no money approved yet for New Horizons to do an extended mission yet, but team members (including Alex Parker from the Southwest Research Institute, who is quoted from Twitter below) are celebrating the milestone. To them, the most promising target (PT1) is the one on the left of the images you see above. Read more about it below the jump.
The Kuiper Belt is a zone of icy objects about four billion miles (6.4 billion kilometers) from the Sun, considered to be leftovers of the building blocks that put together the Solar System billions of years ago. It’s an area that Pluto itself drifts through from time to time on its elliptical orbit around the Sun. Roughly 1,000 objects there have been cataloged, although many more are believed to exist.
The team used Hubble from June 16 to 26 in a test program to look at 20 sky zones for evidence of KBOs, finding two that had never been spotted before by ground-based telescopes. More searching between July and September revealed one object that is “definitely reachable”, NASA stated, and two others that require more scrutiny.
We estimate that PT1 is several 10s of kilometers across. Here’s what that looks like next to Cape Cod and #Comet67P: pic.twitter.com/IHUx6uymO7
Here is where PT1 lies in relation to the rest of the solar system. The yellow path is New Horizons’ trajectory. pic.twitter.com/4aQDEj8oPZ — Alex Parker (@Alex_Parker) October 15, 2014
Here is a gif of the Hubble Space Telescope discovery images of our New Horizons-targetable Kuiper Belt Object PT1. http://t.co/ifw8I4a8Wz
An important and sobering note: even though New Horizons can reach this Kuiper Belt Object, there is no guarantee of an extended mission. — Alex Parker (@Alex_Parker) October 15, 2014
Each of the three candidates would take a while to reach, as they are all about one billion miles (1.6 billion km) beyond Pluto. They’re also tiny, with two estimated at 34 miles (55 kilometers) across and the third at 15 miles (25 kilometers). This makes them 10 times bigger than the average comet, but only 1-2% the size of small Pluto.
“This was a needle-in-haystack search for the New Horizons team because the elusive KBOs are extremely small, faint, and difficult to pick out against a myriad background of stars in the constellation Sagittarius, which is in the present direction of Pluto,” NASA wrote in a press release.
New Horizons’ team plans to ask for the extended mission in late 2016. Meanwhile, the spacecraft (which has been flying ever outwards since 2006) will finally zoom past its main target of Pluto in July 2015.
Uranus as seen through the automated eyes of Voyager 2 in 1986. (Credit: NASA/JPL).
It’s no joke… now is the time to begin searching the much-maligned (and mispronounced) planet Uranus as it reaches opposition in early October leading up to a very special celestial event.
Last month, we looked at the challenges of spying the solar system’s outermost ice giant world, Neptune. Currently located in the adjacent constellation Aquarius, Neptune is now 39 degrees from Uranus and widening. The two worlds had a close conjunction of just over one degree of separation in late 1993, and only long time observers of the distant worlds remember a time waaaay back in the early-1970s where the two worlds appeared farther apart than 2014 as seen from our Earthly vantage point.
Uranus rising to the east the evening of October 7th, just prior to the start of the October 8th lunar eclipse later the same evening. Created using Stellarium.
In 2014, opposition occurs at 21:00 Universal Time (UT)/5:00 PM EDT on October 7th. If this date sounds familiar, it’s because Full Moon and the second total lunar eclipse of 2014 and the ongoing lunar tetrad of eclipses occurs less than 24 hours afterwards. This puts Uranus extremely close to the eclipsed Moon, and a remote slice of the high Arctic will actually see the Moon occult (pass in front of) Uranus during totality. Such a coincidence is extremely rare: the last time the Moon occulted a naked eye planet during totality occurred back during Shakespearian times in 1591, when Saturn was covered by the eclipsed Moon. This close conjunction as seen from English soil possibly by the bard himself was mentioned in David Levy’s book and doctoral thesis The Sky in Early Modern English Literature, and a similar event involving Saturn occurs in 2344 AD.
The footprint of the October 8th occultation of Uranus. Credit: Occult 4.1.
We’re also in a cycle of occultations of Uranus in 2014, as the speedy Moon slides in front of the slow moving world every lunation until December 2015. Oppositions of Uranus — actually pronounced “YOOR-un-us” so as not to rhyme with a bodily orifice — currently occur in the month of September and move forward across our calendar by about 4 days a year.
Uranus (lower left) near the limb of the gibbous Moon of September 11th, 2014. Credit: Roger Hutchinson.
This year sees Uranus in the astronomical constellation Pisces just south of the March equinoctial point. Uranus is moving towards and will pass within a degree of the +5.7 magnitude star 96 Piscium in late October through early November. Shining at magnitude +5.7 through the opposition season, Uranus presents a disk 3.7” in size at the telescope. You can get a positive ID on the planet by patiently sweeping the field of view: Uranus is the tiny blue-green “dot” that, unlike a star, refuses to come into a pinpoint focus.
The apparent path of Uranus from September 2014 through January 2015 across the constellation Pisces. The inset shows the tilt and orbit of its major moons across a 2′ field of view. Created by the author using Starry Night Education software.
Uranus also presents us with one of the key mysteries of the solar system. Namely, what’s up with its 97.8 degree rotational tilt? Clearly, the world sustained a major blow sometime in the solar system’s early history. In 2014, we’re viewing the world at about a 28 degree tilt and widening. This will continue until we’re looking straight at the south pole of Uranus in early 2030s. Of course, “south” and “north” are pretty arbitrary when you’re knocked back over 90 degrees on your axis! And while we enjoy the September Equinox next week on September 23rd, the last equinox for any would-be “Uranians” occurred on December 16th, 2007. This put the orbit of its moons edge-on from our point of view from 2006-2009 for only the third time since discovery of the planet in 1781. This won’t occur again until around 2049. Uranus also passed aphelion in 2009, which means it’s still at the farther end of its 19.1 to 17.3 astronomical unit (A.U.) range from the Sun in its 84 year orbit.
The moons of Uranus and Neptune as imaged during the 2011 opposition season. Credit: Rolf Wahl Olsen, used with permission.
And as often as Uranus ends up as the butt (bad pun) of many a scatological punch line, we can at least be glad that the world didn’t get named Georgium Sidus (Latin for “George’s Star”) after William Herschel’s benefactor, King George the III. Yes, this was a serious proposal (!). Herschel initially thought he’d found a comet upon spying Uranus, until he realized its slow motion implied a large object orbiting far out in the solar system.
A replica of the reflecting telescope that Herschel used to discover Uranus. Credit: Alun Salt/Wikimedia Commons image under a Creative Commons Attribution Share-Alike 2.0 license.
Spurious sightings of Uranus actually crop up on star maps prior to Herschel’s time, and in theory, it hovers juuusst above naked eye visibility near opposition as seen from a dark sky site… can you pick out Uranus without optical assistance during totality next month? Hershel and Lassell also made claims of spotting early ring systems around both Uranus and Neptune, though the true discovery of a tenuous ring system of Uranus was made by the Kuiper Airborne Observatory (a forerunner of SOFIA) during an occultation of a background star in 1977.
A corkscrew chart for the moons of Uranus through October. Credit: Ed Kotapish/Rings PDS node.
Looking for something more? Owners of large light buckets can capture and even image (see above) 5 of the 27 known moons of Uranus. We charted the orbital elongations for favorable apparitions through October 2014 (to the left). Check out last year’s chart for magnitudes, periods, and maximum separations for each respective moon. An occulting bar eyepiece may help you in your quest to cut down the ‘glare’ of nearby Uranus.
When will we return to Uranus? Thus far, humanity has explored the world up close exactly once, when Voyager 2 passed by in 1986. A possible “Uranus Probe” (perhaps, Uranus Orbiter is a better term) similar to Cassini has been an on- and off- proposal over the years, though it’d be a tough sell in the current era of ever dwindling budgets. Plutonium, a mandatory power source for deep space missions, is also in short supply. Such a mission might take up to a decade to enter orbit around Uranus, and would represent the farthest orbital reconnaissance of a world in our solar system. Speedy New Horizons is just whizzing by Pluto next July.
All great thoughts to ponder as you scour the skies for Uranus in the coming weeks!
Artist's conception of the New Horizons spacecraft flying past Pluto and Charon, one of the dwarf planet's moons. Credit: Johns Hopkins University/APL
Here’s Hydra! The New Horizons team spotted the tiny moon of Pluto in July, about six months ahead of when they expected to. You can check it out in the images below. The find is exciting in itself, but it also bodes well for the spacecraft’s search for orbital debris to prepare for its close encounter with the system in July 2015.
Most of Pluto’s moons were discovered while New Horizons was under development, or already on its way. Mission planners are thus concerned that there could be moons out there that aren’t discovered yet — moons that could pose a danger to the spacecraft if it ended up in the wrong spot at the wrong time. That’s why the team is engaging in long-range views to see what else is lurking in Pluto’s vicinity.
“We’re thrilled to see it, because it shows that our satellite-search techniques work, and that our camera is operating superbly. But it’s also exciting just to see a third member of the Pluto system come into view, as proof that we’re almost there,” stated science team member John Spencer, of the Southwest Research Institute.
Watch the difference: Pluto’s moon Hydra stands out in these images taken by the New Horizons spacecraft on July 18 and 20, 2014. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Hydra was spotted using the spacecraft’s Long Range Reconnaissance Imager (LORRI), which took 48 images of 10 seconds apiece between July 18 and July 20. Then the team used half the images, the ones that show Hydra better, to create the images you see above.
The spacecraft was still 267 million miles (430 million kilometers) from Pluto when the images were taken. Another moon discovered around the same time as Hydra — Nix — is still too close to be seen given it’s so close to Pluto, but just wait.
Meanwhile, scientists are busily trying to figure out where to send New Horizons after Pluto. In July, researchers using the Hubble Space Telescope began a full-scale search for a suitable Kuiper Belt Object, which would be one of trillions of icy or rocky objects beyond Neptune’s orbit. Flying past a KBO would provide more clues as to how the Solar System formed, since these objects are considered leftovers of the chunks of matter that came together to form the planets.
Never seen Neptune? Now is a good time to try, as the outermost ice giant world reaches opposition this weekend at 14:00 Universal Time (UT) or 10:00 AM EDT on Friday, August 29th. This means that the distant world lies “opposite” to the Sun as seen from our Earthly perspective and rises to the east as the Sun sets to the west, riding high in the sky across the local meridian near midnight.
2014 finds Neptune shining at magnitude +7.6 in the constellation of Aquarius. Unfortunately, the planet is too faint to be seen with the naked eye, but can be sighted using a good pair of binoculars if know exactly where to look for it. Though the telescope, Neptune exhibits a tiny blue-gray disk 2.4” across — 750 “Neptunes” would fit across the apparent diameter of the Full Moon — that’s barely discernible. Don’t be afraid to crank up the magnification in your quest. We’ve found Neptune on years previous by patently examining suspect stars one by one, looking for the one in the field that stubbornly refuses to focus to a star-like point. Make sure your optics are well collimated to attempt this trick. Neptune will exhibit a tiny fuzzy disk, much like a second-rate planetary nebula. In fact, this is where “planetaries” get their moniker, as the pesky deep sky objects resembled planets in those telescopes of yore…
The position of Neptune, looking eastward on the night of opposition around an hour after sunset. Created using Stellarium.
The 1846 discovery of Neptune stood as a vindication of the (then) new-fangled theory of Newtonian gravitational dynamics. Uranus was discovered just decades before by Sir William Hershel in 1781, and it stubbornly refused to follow predictions concerning its position. French astronomer Urbain Le Verrier correctly assumed that an unseen body was tugging on Uranus, predicted the position of the suspect object in the sky, and the race was on. On the night of September 24th, Heinrich Louis d’Arrest and Johann Gottfried Galle observing from the Berlin observatory became the first humans to gaze upon the new world referring to it as such. Did you know: Galileo actually sketched Neptune near Jupiter in 1612? And those early 18th century astronomers got a lucky break… had Neptune happened to have been opposite to Uranus in its orbit, it might’ve eluded discovery for decades to come!
It’s also sobering to think that Neptune has only recently completed a single orbit of the Sun in 2011 since its discovery. Opposition of Neptune occurs once every 368 days, meaning that opposition is slowly moving forward by about three days a year on our Gregorian calendar and will soon start occurring in northern hemisphere Fall.
Neptune and a one degree field (green) circle. Note that it passes the bright naked eye star Sigma Aquarii on September 15th. Created using Starry Night Education Software.
Now for the “wow factor” of what you’re actually seeing. Though tiny, Neptune is actually 24,622 kilometres in radius, and is 58 times as big as the Earth in volume and over 17 times as massive. Neptune is 29 A.U.s or 4.3 billion kilometres from Earth at opposition, meaning the light we see took almost four hours to transit from Neptune to your backyard.
Neptune is currently south of the equator, and won’t be north of it again until 2027.
Next month, keep an eye on Neptune as it passes less than half a degree north of the +4.8 magnitude star Sigma Aquarii through mid-September, making a great guide to find the planet…
The orbit of Triton on the evening of August 29th, superimposed on a one arc minute field of view. Created using Starry Night Software.
Still not enough of a challenge? Try tracking down Neptune’s large moon, Triton. Orbiting the planet in a retrograde path once every 5.9 days, Triton is within reach of a large backyard scope at magnitude +14. Triton never strays more than 15” from the disk of Neptune, but opposition is a great time to cross this curious moon off of your observing life list. Neptune has 14 moons at last count.
And speaking of Triton, NASA recently released a new map of the moon. We’ve only gotten one good look at Triton, Neptune, and its retinue of moons back in 1989 when Voyager 2 conducted the only flyby of the planet to date. Will Pluto turn out to be Triton’s twin when New Horizons completes its historic flyby next summer?
The Moon also passes 4.3 degrees north of Neptune on September 8th on its way to “Supermoon 3 of 3” for 2014 on the night of September 8th/9th. Fun fact: a cycle of occultations of Neptune by the Moon commences on June 2016.
When will we explore Neptune once more? Will a dedicated “Neptune orbiter” ever make its way to the planet in our lifetimes? All fun things to ponder as you check out the first planet discovered using scientific reasoning this weekend.
The southern hemisphere of Neptune's moon Triton, at a resolution of 600 meters (1,969 feet) per pixel. Credit: Paul Schenk (LPI, Houston) from Voyager 2 images acquired August 1989
Talk about recycling! Twenty-five years after Voyager 2 zinged past Neptune’s moon Triton, scientists have put together a new map of the icy moon’s surface using the old data. The information has special relevance right now because the New Horizons spacecraft is approaching Pluto fast, getting to the dwarf planet in less than a year. And it’s quite possible that Pluto and Triton will look similar.
Triton has an exciting history. Scientists believed it used to be a lone wanderer until Neptune captured it, causing tidal heating that in turn created fractures, volcanoes and other features on the surface. While Triton and Pluto aren’t twins — this certainly didn’t happen to Pluto — Pluto also has frozen volatiles on its surface such as carbon monoxide, methane and nitrogen.
What you see in the map is a slightly enhanced version of Triton’s natural colors, bearing in mind that Voyager’s sensors are a little different from the human eye. Voyager 2 only did a brief flyby, so only about half the planet has been imaged. Nonetheless, the encounter was an exciting time for Paul Schenk, a planetary scientist at the Lunar and Planetary Institute in Houston. He led the creation of the new Triton map, and wrote about the experience of Voyager 2 in a blog post.
“Triton is a near twin of Pluto,” wrote Schenk. “Triton and Pluto are both slightly smaller than Earth’s Moon, have very thin nitrogen atmospheres, frozen ices on the surface (carbon monoxide, carbon dioxide, methane and nitrogen), and similar bulk composition (a mixture of ices, including water ice, and rock. Triton however was captured by Neptune long time ago and has been wracked by intense heating ever since. This has remade its surface into a tortured landscape of overturned layers, volcanism, and erupting geysers.”
He also added speculation about what will be seen at Pluto. Will it be a dead planet, or will geology still be affecting its surface? How close will Triton be to Pluto, particularly regarding its volcanoes? Only a year until we know for sure.
Animation of Pluto and Charon showing nearly a full rotation (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)
Now here’s something I guarantee you’ve never seen before: a video of the dwarf planet Pluto and its largest moon Charon showing the two distinctly separate worlds actually in motion around each other! Captured by the steadily-approaching New Horizons spacecraft from July 19–24, the 12 images that comprise this animation were acquired with the Long Range Reconnaissance Imager (LORRI) instrument from distances of 267 million to 262 million miles (429 million to 422 million km) and show nearly a full orbital rotation. Absolutely beautiful!
For a close-up video of the two worlds in motion, click below:
Pluto and Charon rotation movie from New Horizons (enlarged view)
Pluto and Charon are seen circling a central gravitational point known as the barycenter, which accounts for the wobbling motion. Since Charon is 1/12th the mass of Pluto the center of mass between the two actually lies a bit outside Pluto’s radius, making their little gravitational “dance” readily apparent.
(The same effect happens with the Earth and Moon too, but since the barycenter lies 1,700 km below Earth’s surface it’s not nearly as obvious.)
“The image sequence showing Charon revolving around Pluto set a record for close range imaging of Pluto—they were taken from 10 times closer to the planet than the Earth is,” said New Horizons mission Principal Investigator Alan Stern, of the Southwest Research Institute. “But we’ll smash that record again and again, starting in January, as approach operations begin.”
Artist concept of the New Horizons spacecraft. Credit: NASA
Launched January 19, 2006, New Horizons is now in the final year of its journey to the Pluto system. On August 25 it will pass the orbit of Neptune – which, coincidentally, is 25 years to the day after Voyager 2’s closest approach – and then it’s on to Pluto and Charon, which New Horizons will become the first spacecraft to fly by on July 14, 2015, at distances of 10,000 and 27,000 km respectively. Find out where New Horizons is right now here.
Source: New Horizons
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Artist's impression of the New Horizons spacecraft. Image Credit: NASA
This fall, Universe Today plans to get in-depth into the Pluto planethood debate. I (Elizabeth Howell) just launched a crowdfunding project on a new platform called Beacon that will allow me to fly down to Washington, D.C. for several days to interview Pluto scientists.
Should the project be funded, a few fun things are going to happen. Here, Universe Today readers will get a series of articles into the Pluto planethood debate. We’ll examine the controversial International Astronomical Union vote and why certain scientists still don’t believe Pluto is a dwarf planet today.
The question has special relevance today because NASA’s New Horizons spacecraft is on a journey to Pluto, and is less than a year from getting there. Examining Pluto will give scientists a window into how the solar system formed, which in turn gives us clues as to how the Earth came to be. We’ll have some stuff about the science as well; stay tuned for the details!
You’ll also get the chance to support astronomy education and outreach. I’m pleased to announce that CosmoQuest will be a partner on the project, receiving 15% of all proceeds for the project. If you contribute $250, $500 or $1,000, they will receive an additional 15% of your money. Contributors at this level will have their name mentioned in at least two of a series of six podcasts I will do for CosmoQuest’s 365 Days of Astronomy. There are other fun perks, too, so check out the Beacon page for more.
As a freelance journalist, my challenge with doing travel stories is I have to pay my own way. Beacon solves that problem. It will allow me to spend a few days in person with scientists, gathering pictures and videos and podcasts, instead of relying on the phone interviews I usually conduct.
After paying contributions to CosmoQuest and to Beacon, every single cent remaining will be for travel expenses only. The money will give me a flight to Washington, D.C., a few nights in a reasonable hotel, and a car rental. I promise you that I’m extremely frugal — ask my mortgage broker — and I will spend every dollar of your contributions wisely. Additional money after $2,400 will allow me to draw a salary for the days I am there. If a substantial amount of extra money is raised, I’ll consider a second trip to D.C.
A NASA “poster” marking the one year to Pluto encounter by New Horizons. Credit: NASA
I’m not one to brag about my experience, but I will say that I’ve been proudly writing about space for a decade for many publications (including Universe Today). I’m one of the few journalists in Canada to focus on space virtually full-time. And I have covered some fun stories, such as three shuttle launches (2009-10), Chris Hadfield’s last mission (2012-13) and participating in a simulated Mars mission in Utah (early 2014). I see space as a field where I can always learn more, and this will be a great chance to share what I learn about Pluto with you.
Any questions? Feel free to get in touch with me at contact AT elizabethhowell DOT ca or to leave comments below. I likely won’t be able to respond until tomorrow as this launch coincidentally falls on a planned vacation day for me, but I promise that for the rest of the campaign I’ll answer your queries as fast as I can.
