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We knew that, if the Webb telescope could make it to the L2 Lagrange Point in one piece and deploy properly, this would be an exciting season for astronomers–but, even so, the parade of stunning new images from outer space are marvelous and demand comment. Today’s treasure is a picture of Planet Neptune and its moons as imaged by the near-infrared camera on Webb. The ice giant Neptune is made of strange cold things with a great pall of methane gas over them. Methane gas is very opaque to infrared light (which it absorbs) and so the planet looks like a frosty, haunted bowling ball with glass rings.
Ever since Pluto got demoted to “dwarf planet”, Neptune is the outermost world of our solar system. Yet the great gas giants…or even the trans-Neptunian objects like Eris and Haumea get all of the attention. No space craft has even visited Neptune since Voyage II rolled by in 1989 (the first and last time a probe entered the Neptune system).
Aside from the spectral rings, the image shows some bright sparks in a line along Neptune’s Tropic of Capricorn (which is not called that, but you get the idea). These bright spots are caused by high altitude methane clouds which are made of methane ice (which reflects infrared light better than methane gas does).
The full Webb photo has a striking focal point! Pulling back we see that Neptune’s largest and strangest moon Triton outshines the giant world it orbits. This is because Triton (which is named for the Greco-Roman deity Neptune’s merman super-son) is covered in a sheet of frozen nitrogen which reflects 70% of the sunlight which strikes it–so Triton glows like an aquamarine star in this photo. Ultimately Triton might well turn out to be be more interesting than Neptune: it is the only large moon in the solar system with a retrograde orbit (an orbit opposite of the planet’s rotation). Such an unusual orbit suggests that the moon was a little world captured by the ice giant long ago.
Triton is larger than Pluto and is one of five moons in the solar system known to be geologically active (the others being Io, Europa, Titan, and Enceladus). Voyager II spotted geysers of nitrogen gas venting from the moon. Clearly cryovolcanic activity is taking place below the strange patchwork of old ice (as explained in this confusing yet compelling map/diagram) and lakes of liquid water may exist below the moon’s crust.
I am going to keep staring at images of our strange far-off neighbor world, but I can’t wait to see what Webb photographs next!
While idly scanning trans-Neptunian objects & suchlike miscellaneous dwarf planets of the outer solar system, Ferrebeekeeper was stunned to see a familiar name–GongGong, the dark water dragon who messed up Chinese cosmology and nearly destroyed the world. In Chinese mythology, GongGong’s reign of chaos was stopped by the gentle creator goddess Nuwa. However, in order to repair the damage wrought by the naughty dragon, Nuwa was forced to jerryrig creation back together with turtle legs and river rocks (and the end result is decidedly more rickety than the original).
The dwarf world Gonggong was discovered by astronomers waaaaaaay back in 2007. Although it is not the most famous dwarf planet in the solar system, it is not inconsequential in size and has a diameter of 1,230 km (760 mi). Gonggong’s eccentric ecliptic orbit takes 550 Earth years and the planetoid rotates very slowly as well. At its perehelion (when it is closest to the sun) it is 55 AUs from Earth, however at its apehelion it is 101.2 AUs (1.514×1010 km) away from the gentle sun. Brrrr! Gonggong was last at perehelion fairly recently, in 1857, and now it is moving farther and farther away–so if you left your wallet there in 1857, you may just want to get a new one. The orbital diagram below shows the orbit of Gonggong (in yellow) contrasted with that of Eris.
Like the lozenge-world Haumea, Gonggong is a strange reddish pink color because of organic compounds known as tholins which cover its ancient ice. In some stories, the evil water dragon Gonggong had a copper head, so maybe the name suits it. Oh, also, in Chinese mythology GongGong has a sidekick, a wicked nine-headed demon named Xiangliu. Gonggong the planetoid has a tiny moon which bears this name. Finally, Chinese mythology is weirdly ambiguous about whether Nuwa and Zhu Rong finished off GongGong or whether he escaped to cause trouble another day. If I were hiding out from a bunch of quasi omnipotent Earth deities for thousands of years, I know where I would go!
Did you know it has been 30 years since a spacecraft swung by Neptune? Voyager II was the first and last spacecraft to visit the strange ice world which (with the demotion of Pluto) is the outermost planet of our solar system. A ball of gas, ice, rock and iron 17 times the size of Earth, Neptune is the third most massive planet and is the most dense of all the giant planets. However we know surprisingly little about this distant neighbor–a fact which was vividly demonstrated this week when astronomers discovered an unexpected new moon orbiting the planet. This new moon brings the tally of Neptune’s moons to 14. Mark Showalter, a researcher at the SETI institute in California, discovered the little satellite accidentally, while working on another project and the new body was confirmed with the Hubble Space telescope (which is also still out there, by the way).
Neptune’s largest moon is the retrograde Triton. The second largest moon is Proteus, an irregular polyhedron with a diameter of 420 kilometers, named after the shape-shifting old man of the sea. The new moon, which is named “Hippocamp”, after a seahorse like Greek sea monster (above) has a diameter of about 20 kilometers (about the length of Manhattan) and seems to have been formed from ejecta left over from when some primordial body slammed into Proteus.
Astronomers have spent comparatively little time studying Uranus and Neptune compared to the other planets of the solar system–which is somewhat ironic since most of the exoplanets we are finding are ice giants. It seems like they might be noticing this gap in their knowledge. A new mission to the ice giants is the third top mission priority in a vote-based ranking of proposed probe missions (by astrophysicists…nobody asked me what I want *cough* balloon mission to Venus’ atmosphere). Hopefully we will get our act together and launch a modern robot out to the big blue ice worlds in the not-too-distant future.
We haven’t had much of a winter so far…which is fine with me. I dislike the cold part of the year and I was happy today when it was unexpectedly sixty and I got to bike in to work. And yet there is supposed to be a blizzard tomorrow!
So, to celebrate the season of snow and ice here is a little gallery of crowns which are meant to resemble snow and ice. Some of them are really pretty—especially the ones which are actually made of icicles (which I have always loves for their otherworldly frightful beauty).
I wish that more of them looked like snowflakes though—they really have their own disturbing alien allure. Anyway, I hope you are inside enjoying a bog mug of your favorite hot beverage and nestled by a fire. And for my tropical and southern hemisphere readers, why do you guys never invite me to come visit?
Happy blizzard. I’ll see you all tomorrow.
There is a lot to talk about lately: this dreadful never-ending election, spooky Halloween subjects, the president’s laudable plan to land humans on Mars, the fact that the Olympics have completely moved to East Asia….but, for the moment, let’s ignore all of that to talk about a ghastly dark snowball the size of Iowa. I am not talking about any old snowball, I am talking about 2014 UZ224, a dwarf planet which was recently discovered by an astronomy team at the University of Michigan.
2014 UZ224 has a diameter of about 530 kilometers (330 miles): it is about half the size of Pluto. Perhaps it is not even a true dwarf planet—but what else should we call it. Located deep in the Oort Cloud, the little world is 14 billion kilometers (8.5 billion miles) from the sun (which is something like a thousandth of a light year). It takes 1,100 years to complete a single orbit of our star. There are many of these Oort Belt objects (Ferrebeekeeper has talked about Sedna, Eris, and Haumea before), but it always special to find a new member of the solar system. Or maybe not…the news of the world barely seemed to note the little iceball at all. I don’t know whether to be pleased at how mundane such discoveries are becoming, or appalled at how blase and jaded we are. I bet Herschel would still be excited!
Last week I meant to include an elegiac post to Rosetta, an astonishing space mission, which stretched out over a dozen years and logged 4.9 billion miles of travel. Rosetta was launched way back in 2004. It was originally supposed to rendezvous with comet 46P/Wirtanen in 2011, but problems with the launch in Guyana caused the probe to miss the launch window for the primary mission. The ESA changed the mission parameters so that the spacecraft ended up exploring Comet 67P/Churyumov–Gerasimenko instead (this second comet was functionally the same as the first—except for a much more difficult-to-say name). During its journey to the comet, Rosetta also flew by Mars and two asteroids. After flying by Mars in February of 2007, the craft flew by Earth in November of 2007. It caused a miniature panic when astronomers of the Catalina sky survey spotted it and misidentified it as a 20 meter near-Earth asteroid on a possible collision path with Earth!
The spacecraft arrived at Comet 67P/Churyumov–Gerasimenko in August of 2014 and the most famous…and infamous…part of the mission took place in November of that same year, when Rosetta launched the Philae lander to harpoon itself to the comet. Although Philae (which was named after a Rosetta-like obelisk with the same text in Greek and Egyptian) succeeded in landing and not bouncing off into the void, sadly the little lander came down in a miserable crevasse. Scientists intimately studied pictures of the comet (from Rosetta) until they found the lander in the icy chaos. It was a pretty ghastly scene which reminded me of my sock drawer (if it were dropped from space onto Tungnafellsjökull glacier).
(See it there at bottom right?)
Rosetta’s long and mostly successful mission came to an end last Friday in a truly operatic fashion. Mission controllers chose to use the last vestiges of power to smash the orbiter into the comet! Well, although I am saying “smashed” what actually happened was more like a grandmother walking into a snowbank. The lander was lowered onto the comet at about one mile per hour. Except, despite the fact that Rosetta traveled more than 5 billion miles (“uphill both ways”) it was not designed for landing and its last communication was a photo just above the comet surface. RIP Rosetta, you were one good probe!
The North Pole of Enceladus during the October 30th, 2015 Cassini Flyby (NASA/ESA/ASI)
Since 2004, the Cassini spacecraft has been in orbit around Saturn. The robot probe (a joint effort of NASA, ESA, and the Italian space agency) received the most press when it launched a flying saucer lander onto Saturn’s planet-like moon Titan, but it is still out there doing amazing work. Last week, while I was busy writing about Halloween themes, the probe made its closest pass yet to Saturn’s ice moon, Enceladus. Enceladus is only 500 kilometers in diameter and it is coated in ice, but it is of great interest to scientists because ice plumes venting from the moon’s south pole seem to indicate a large polar subsurface ocean of liquid water. Warmed above freezing by tidal flux, this ocean beneath the ice probably has a thickness of around 10 km.
View of Enceladus’ south pole geyser, backlit by Saturn
On October 30th, Cassini flew by the icy moon at the dangerously close distance of 30 kilometers (18.6 miles). The probe was directly above the south pole of Enceladus and it collected a little flake of ice to analyze (which strikes me as incredibly amazing and beautiful). It will take some time for the ship’s devices to assay the drop of water from an alien ocean, but Cassini also snapped some photos which we already have. These are taken from point blank range above the south pole. The ocean is down there beneath the scratches and scars. What is the nature of this icy ocean? How long has it been there? Could it possibly harbor life?
The Mountain on Ceres (Dawn Space Probe, NASA)
Now that the Dawn spacecraft has actually reached the dwarf planet Ceres, Ferrebeekeeper has been writing less about it! Today we will remedy that with a spectacular photo taken from the robot probe. Remember the strange reflected light from Ceres which the world was so fascinated by? Well now that Dawn is a mere 1500 kilometers (900 miles) from Ceres, we have discovered that the reflections come from a huge glistening mountain—a strange anomaly on the puckered cratered terrain of the dwarf world. This mound is likely made of some sort of ice and is about the same size as Mount McKinley—the highest mountain in North America (approximately 6,000 meters (20,000 feet) tall). Geologists (or I guess I should say astrophysicists) are baffled by why the mountain is there—but I am sure that theories will be forthcoming.
Pundits and media personalities talk about this singular ice mountain as a pyramid (possibly to get hits), but to me it looks like a huge limpet made of ice. Here is a 360 degree panoramic sweep around of the mountain (which needs a name!). I wonder what other odd things are hiding in less plain sight on the little world.
Artist’s redition of New Horizons approaching Pluto and Charon
After years and years and years of waiting, NASA’s New Horizons mission is officially in its “flyby” stage. As I write, the robot probe is desperately snapping pictures and taking readings of Pluto and its moon Charon. The closest pass-by will arrive next Tuesday when New Horizons will be a mere 12,500km from the dwarf planet.
Hmm, I can sort of see a heart, a whale, and a donut (Photo courtesy of NASA, New Horizons)
Today’s post serves to alert you to keep your eyes peeled next week! I will be eagerly awaiting news of the developments and I will relay them to you as quickly as possible–although Pluto is 320 light minutes away from us (give or take a few hundred million kilometers) so nobody is going to be caught up in real time. In the meantime, New Horizons is already learning more about the dwarf planet than we have ever known before: this is a mission to a world almost wholly unknown to us despite the fact that we are neighbors in the same star system! Pluto has a distinctive reddish pinkish hue and features an array of high-contrast features (presumably composed of layers of exotic ices) which, to human eyes, superficially resemble familiar shapes. Most notable is a large cardiod-shaped feature in the southern hemisphere unsurprisingly dubbed “the heart”. There is also a planet sized stain resembling a whale and a smaller stain which looks like a donut. No doubt we will get a better idea about these bright/dark areas during the close-up approach next week. Right now I hope people are appreciating my artistic prescience!
Mister SETI (Wayne Ferrebee, 2012, oil on panel)
The main thing which is currently striking to scientists (who have better things to worry about then whether methane ice looks like a whale) is how dissimilar Pluto is from its moon Charon. The two objects are closer size-wise than any other planet/moon system in the solar system, yet Charon is completely unlike Pluto in appearance and make-up. The moon, which is named after the ferryman of the underworld, is gray and nearly featureless and has no atmosphere (I should have mentioned that Pluto does have an atmosphere—at least at this phase of its strange orbit).
Hooray for New Horizons! Considering where it is and what it is currently doing, I almost find it hard to think of it as real, but it most assuredly is. Also hooray for us! We have some bad moments, but we can launch a highly functional robot out of Earth’s gravity well to the edge of the solar system! It isn’t a space colony on Venus—but it’s a start. Our arms are growing longer and our apprehension keener. I almost can’t wait for next week, yet somehow I think I’ll still manage to enjoy the weekend.
The Great Basin on Saturn’s Tethys (Credit: Cassini Imaging Team)
It’s been too long since we headed out to space. This is true of humankind, but it is also true of this blog…so today we are going to cast our eyes across the solar system to Tethys a mid-sized moon of Saturn. In 1684 the Italian astronomer Giovanni Domenico Cassini discovered Tethys. He initially named the moon in honor of Louis XIV, but his choice was later changed so that the moon is named for a first generation Greek titan-goddess. The moon has been approached by several human spacecraft, most notably…Cassini, which has dropped by several times (the robot space probe is named after the astronomer—the poor fellow has not been drifting in space since the 17th century).
Giovanni Domenico Cassini
Of all the major moons in the solar system, Tethys has the lowest density: 0.98 g/cm3 ! This means that almost the entire moon is made of frozen water—it is essentially a huge round ice cube floating around Saturn. Tethys has two extremely prominent features—a giant crater 450 kilometers (280 miles) across (named Odysseus) and a huge ice canyon 2000 kilometers (1200 miles) long, 100 km (62 miles) wide, and 3 km (1.8 miles) deep, which stretches most of the way across the moon. Unsurprisingly astronomers speculate that the two features are related and the massive impact which created Odysseus melted a chasm along the entire side of the planetoid.
Although you might be inclined not to expect much activity from a ball of ice in the depths of space, Tethys seems like it may be geologically active, or, at least, it may have been once. The area around the hemisphere is comparatively flat and free of craters—which suggests that tidal flux from Saturn causes some melting—and possibly cryovolcanoes.
Ithaca Chasma: The Great Rift on Saturn’s Tethys
(Credit: Cassini Imaging Team)
Paleontologists and sharp-eyed readers already know the name Tethys. During the age of Pangaea (when all of the world’s continents joined to form a single land mass), the great ocean in the midst was named the Tethys Ocean. In Greek mythology, Tethys was the daughter of Gaea (the mother earth) and Uranus (the heavens). She was regarded as the mother of all waters and was married to her brother Oceanus, the first lord of the seas. The astronomers of the age of enlightenment who renamed the moon, could not have known it was composed mostly of water, but they chose well.
ferrebeekeeper 