You are currently browsing the tag archive for the ‘solar system’ tag.
Hi everyone! Sorry that the posts were thin on the ground last week. The head druid told me that I needed to honor the solstice by taking some time to reflect on the meaning of things [citation needed]. Anyway…since I didn’t blog last week, I failed to post these astonishing pictures of Jupiter’s giant moon Ganymede, which were photographed by NASA’s Juno spacecraft as it slaloms though the Jovian system.
Although its lack of atmosphere and pockmarked plains of dust make it superficially resemble Earth’s moon, Gannymede is a very strange and unique heavenly object Of the 200 known moons in the solar system, it is the largest. Indeed it is 26% larger than the planet Mercury by volume (although it is only 45% as massive as the metalliferous first planet). Ganymede has a diameter of 5,268 km (3,273 mi), so each pixel in the full size image of the Jovian moon is equal to a kilometer (although you may want to check out the NASA image to really savor that scale–since WordPress has a noteworthy penchant for scrunching up my images in incomprehensible ways).
Alone among moons in the solar system, Ganymede has a magnetic field, albeit a rather meager one compared to Earth or Jupiter. Scientists surmise that the magnetic field is created by convection within the liquid iron core of the moon–although answers are not forthcoming as to why it has a liquid iron core to begin with (these planetary cores seem to be the real determinant of what planets are like, but I feel like we know precious little about them). Thanks to its size (and maybe thanks also to its magnetosphere), Ganymede has a very thin oxygen atmosphere…but that just creates more question, since elemental Oxygen has a tendency to instantly bond to all sorts of other elements. The 20 percent or so of oxygen in Earth’s atmosphere did not become a mainstay until about 1.5 billion years ago when photosynthesizing bacteria finally became so prevalent that they overcame the constant loss of atmospheric oxygen thanks to oxidation. Hopefully Juno’s survey will help us solve atmospheric mysteries on Ganymede. Ganymede is also believed to have a vast subsurface ocean of icy water tucked away somewehere beneath its surface. Astronomers have reasonably speculated that this Ganymede underworld ocean may contain more water than all of Earth’s oceans combined!
Ganymede is a Galilean moon–which means it was discovered by the great scientist, and is one of the first objects ever discovered to orbiting another planet (I still sometimes imagine the thrill Galileo must have felt when he realized what he was seeing). I wonder what surprises Juno will send back for us!
Based on what we are learning from the exoplanet surveys of the past decade, our galaxy is the home of an immense number of Jovian-size gas giant planets. There are countless “hot Jupiters”–gas giants located close to their stars which whip around and around their orbits in ridiculously short “years”. There are frigid slow gas giants and super massive ones—practically brown dwarves– which are larger than Jupiter. There is an endless proliferation of Uranus and Neptune type giants. Imagine them all glittering in strange colors with weird shapes. They are cloaked in alien clouds and covered in mysterious storms. Who knows what lies beneath?
All of these billions of giant planets seem pretty hypothetical to me as I sit here at my cramped & cluttered desk on solid little Earth. Yet they exist. They are out there in numbers too vast to comprehend. However, right now, NASA is conducting the most comprehensive exploration yet of the gas giant we can access. Juno’s mission is just getting underway in earnest, and the largest gas giant in our own backyard should reveal lots about all of the billions which are out of reach.
I am sad that I can neither understand nor convey the loftiness of this crazy ongoing mission. It is an astonishing undertaking—but we are so inundated by with murky political battles and vulgar popular drivel, that it is hard to see the utterly astonishing nature of this undertaking.
Maybe I can put it in perspective somewhat. Imagine back to the year 1609 AD when Henry Hudson was first seeing the river which was later named after him. Before him was an exquisite expanse of islands, bays, and sparkling river. The vast waterway flowed down from unknown mountains into a bay surrounded by lovely islands. The whole expanse was filled with flocks of unknown birds and schools of fish. Beyond the thriving marshes, mysterious forests were filled with moving shadows.
Now multiply that a billion times: replace Henry Hudson with a tiny fragile robot and replace the Hudson River with luminous gas oceans large enough to entirely submerge scores of Earths. That is what is happening right now. As you sit reading this on a little glowing screen, we are making fundamental discoveries about a whole planet.
On August 27, 2016, Juno executed the first of 36 orbital flybys over Jupiter. The doughty spacecraft was only 4,200 kilometers (2,500 miles) above Jupiter’s atmosphere. It sent back the first detailed images of the north pole of Jupiter—and it is unlike the rest of the planet.
The North Pole of Jupiter as seen by Juno [NASA]
To quote Scott Bolton, one of the lead scientists of the Juno mission, “[The] first glimpse of Jupiter’s north pole…it looks like nothing we have seen or imagined before….It’s bluer in color up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to — this image is hardly recognizable as Jupiter. We’re seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features.”
Jupiter’s clouds contain whole continent-like regions of air which are different than the rest of the planet’s storms and whirls. We don’t yet know why or how, but we are finding out. As we do so, we are peeling back a layer of mystery which surrounds all such worlds.
Solar Radiation Streaming over the North Pole of Jupiter
Pluto (Photo from NASA’s New Horizons mission)
As promised we are dedicating today’s post to the New Horizons spacecraft. The unmanned robot probe (which is the size of an unwieldy motorcycle) flew past Pluto at 7:49 a.m. EST, traveling at nearly 50,000 kilometers per hour (31,000 mph). At its nearest approach, the craft was only 1200 kilometers (7500 miles) above Pluto’s surface—closer to Pluto than Brooklyn is to Botswana.
Because of the shape and size of the solar system, the telemetry of the mission, and the niceties of radio-communication, NASA did not receive the information dump from the spacecraft until 00:53 GMT Wednesday which is uh…approximately right now! So I haven’t had any time to groom the Pluto data! Today’s post is thus more of a laurel. But the information does exist—the craft survived and completed its mission. We have a trove of knowledge about Pluto to help scientists understand the nature of the solar system—or to conceive of what kinds of new questions to ask about other planetary systems. Maybe I’ll be desperately writing another post tomorrow if scientists unexpectedly find canals on Pluto or discover that Nyx is really a giant egg or something, but most likely this data will take a long time to process and understand. Such is the nature of science (and most worthwhile pursuits). So what is the purpose of this post?
I have never been unduly upset about the designation “dwarf planet” for things like Pluto, Ceres, Eris, and Haumea. However I did grow up with “My very educated mother just served us nine pizzas” (a much snappier mnemonic than “My very educated mother just served us nothing”), and the idea of Pluto as the final planet still holds undeserved weight in my subconscious. I have thus been taking NASA’s self-congratulatory PR announcements seriously when they say “we complete the initial reconnaissance of the planets.” That sounds right to me. Humankind has gathered a great deal of information about the solar system. Now it is time to brainstorm some new objectives before the fickle public loses its interest and wanders off.
This graphic is old…What next?
There is a national consensus that we should be spending all of our money on expensive cell phones and vastly overpriced (yet disturbingly ineffectual) medical care. The space age is reckoned to be over—and space should now be left to the likes of Elon Musk and other James Bond villain-ish mega billionaires. I think this is wrong, wrong, wrong, wrong, ever so wrong. Now that we have some ideas about what is out there we should use our hard-won knowledge to do tremendous things! My favorite next step is an atmospheric mission to Venus. Let’s send some cool space blimps to sit in the high atmosphere of our sister planet and maybe launch some weird little drones and smaller balloons into the atmosphere. We could find out whether a floating colony is even feasible. Plus it would be like the Montgolfier brothers and the Wright brothers all over—on another world!
Oooh! Can we use a donut-shaped balloon?
The idea of a human mission to Mars and a submarine mission to Europa also have great merit—but I see them as more difficult and with less practical purpose. What are your favorite ideas about what to do next? This seems like a good moment to at least talk about the direction we are headed, even as we sip champagne and dance joyously about what we have done.
“Champagne in Space” by Jshinncreative on DeviantArt
Today features a short but vivid post borrowed from the futurist/science fiction/space blog io9 (which in turn took it from XKCD). Above is a map of all the surfaces of the solar system’s planets and moons flattened out and stitched together. The map was created by Randall Munroe and it does a superb job of explaining the relative size of rocky objects in the solar system. For obvious reasons the gas giants (and the sun!) have been excluded, but so too have small rocks and dust. For fun (um, I hope), the mapmaker also included an area equivalent to all human skin–which, distressingly, seems to be about the size of Hainan.
Russian concept art for a cloud colony in the upper atmosphere of Venus, (proposed in 1970s)
This map also emphasizes my most ardent fantasy of solar system colonization: I don’t really want to set up shop on Umbiel or Ceres, but I have a long-lasting interest in colonizing Venus. Sadly most of the rest of humankind is having trouble grasping this concept (possibly because the surface of Venus is a molten hellscape featuring boiling lead, sulfuric acid rain, and crushing pressure). Remember though, we don’t need to ever go down to the Venutian surface: we can hang around in floating bouncy castles drifting through the balmy spring at the top of the atmosphere. Imagine taking your family zeppelin out for a night on the floating town! All of the people who express such an unwholesome interest in cold resource-poor Mars should pause to reexamine its relative area on Mr. Munroe’s excellent map!
Left to right: Mars, Earth, Venus
Time lapse photo of the movement of 2012 VP113 (color digitally added)
Astronomers today announced the discovery of a new dwarf planet at the edge of the solar system. Until the appropriate nomenclatural bodies settle on a snappier name, the tiny body will be known by the unwieldy moniker of 2012 VP113. The little planetoid is estimated to measure about 450 kilometers in diameter (so it is much smaller than other plutoids like Haumea (which is approximately 2,000 km x 1,500 km x 1,000 km). Speaking of Haumea, which has a mysterious pink spot, the new object (which I’ll call VP113, for short) is also suspected to be light pink because radiation causes the frozen gases to decay to that color.
Even when it is closest to the sun, the little planetoid is still 12 billion kilometers (7.4 billion miles) distant from our home star–but at the farthest extent of its orbit 2012 VP113 is a whopping 70 billion kilometers (44 billion miles) from Sol. That’s almost a thousandth of a light year! The irregular orbit takes 44,000 Earth years to complete—which means one year there is a very long time!
You might be wondering why I am taxing your brain with obscure snowballs, but, astronomers are very interested in VP113 because of what it might reveal about the origins of the solar system. In 1951, the Dutch-born astronomer, Gerard Kuiper, predicted the existence of a vast cloud of icy objects at the remote edge of the solar system. The Kuiper belt has indeed been discovered—it is a belt of dust and icy objects approximately between Neptune and Pluto. In 1950, a Dutch astronomer, Jan Hendrik Oort revived an idea from the 1930s (from Estonian Ernst Öpik) that there was a huge spherical cloud of comets, vapor, and icy planetoids at the edge of the solar system—beyond even the orbits of miniature planets Eris, Sedna, and VP113. [I don’t know why all the scientists who theorized about the solar system’s icy edges were northern Europeans].
The discovery of VP113 proves the existence of the inner Oort cloud and provides astronomers with a source of information about the objects in the Oort cloud. Additionally the extremely strange orbits of VP113 and Sedna begin to suggest that an alien star disturbed the Oort cloud in the past—or that there may still be an Earth sized planet at the true edge of the solar system.
This week’s posts [concerning translucent sea slugs, wasps named for a crazy pop star, an elusive Indochinese cousin of the cow, and whole sunless ecoystems] have all been about finding new life-forms. There is, of course, only one place such a topic can ultimately wind up—far beyond the living jungles, azure seas, and swirling clouds of our beautiful home planet, out in the immensity of space where the greatest question of all waits like a magic golden apple spinning in darkness.
Is there life elsewhere?
Unfortunately the current answer is incomplete: all known life–in all of its ineffable variety–is Earth-based…yet the universe is vast beyond comprehension. So I’m going to mark this down as “probably.”
Chang E and the Lunarians
Many ancient societies reckoned that other worlds existed. The Norse had their nine worlds joined together by the great ash tree Yggrdasil. The Chinese had myths about Chang’e and the Jade rabbit on the moon. Even the stolid Christians believe in heaven & hell, which are places filled with intelligent beings that are not on earth (ergo, alien realms somewhere out there in the multiverse). William Herschel, great astronomer of the Enlightenment, believed that life was everwhere—particularly everywhere in the solar system.
Sigh–those were simpler times…
When humankind entered space age, we used our burgeoning technology to examine the solar system for signs of Sir William’s spacefolk. Although we did not find the Venusian space hotties we were looking for (dammit), we did discover that among our neighboring planets, there are several other possible homes for earthlike living things. The cloud tops of Venus are inviting and could host bacteria-like life (although I hope not, since I want us to build a second home there). For centuries, scientists and fabulists speculated about life of Mars. We now know that the Martian magnetosphere died and the planet’s atmosphere was swept away, but perhaps there are some hardy extremophile bacteria living in the Martian rocks somewhere. It’s a sad scenario to imagine them on their dying world—like little kids left in a bathtub going cold. Certain moons of Jupiter & Saturn seem to be the real best bet for life in the solar system. The Jovian moons Europa, Ganymede, and Callisto are all believed to have extensive liquid oceans beneath their crust. Likewise the Saturn moons Titan and Enceladus are believed to have subsurface water. The discovery of life on Earth which did not directly require photosynthesis (like the cold seeps from yesterday’s post) has given scientists hope that bacterial mats—or maybe something even more advanced–exists on one of these moons.
So maybe there are some bacteria analogs or conodont-like creatures squiggling around in some cranny of the solar system. Perhaps life takes on an unknown form and we already flew over a clever, good-hearted ammonia-based life form on Enceladus (which NASA analysts then promptly dismissed as a snowbank), but I doubt it. The true answers to the questions about life lie out there among the stars. Exoplanets are being discovered at a tremendous rate and everyone hopes that some of the more earthlike examples harbor life. Unfortunately our technology is nowhere close to being able to spot the planets themselves and gauge whether life is there by means of spectrograph. We are stuck waiting for peers who are either broadcasting radio signals or screwing around with the fundamental nature of existence in such a way that would bring them to our attention. Indeed as humankind’s technological savvy grows, scientists are looking for more sophisticated signs of advanced life such as black holes of less than 3.5 solar masses or sophisticated particle radiation which could only be created (or detected) by civilizations of huge sophistication. All we can say right now is that, after a hundred years of looking, we have not found a lot of radio chatter in our neck of the galaxy—which is an answer of sorts itself.
Perhaps we are among the first sentient beings in this area of space (or anywhere, for that matter). The first generation of stars had to live and die before there were any raw materials for chemically based life. It took billions of years to get where we are, and, despite a few perilous missteps and accidents, life on Earth has been lucky. In my opinion some of those planets we are discovering are almost certainly covered with microbial life, but not many have little green scientists in many-armed lab coats firing up their radio telescopes (or forging little suits of chain mail a few hundred years behind us).
The Arecibo message as sent 1974 from the Arecibo Observatory.
In writing about the Curiosity rover, I humorously mentioned how much it looked like the aliens from golden age science fiction. It seems we are also broadcasting retro style messages to the stars. Above is the print-out version of the Arecibo message—one of the loudest broadcasts we have sent. It’s like a macramé knitted by Dr. Zoidberg’s great aunt or a valentine from Atari’s space invaders! Imagine if you pointed your radio telescope at the heavens and received a message like that! Maybe the aliens are scared of us or maybe they don’t want to talk to a species with such homespun tastes!
Some day in the future (artist’s interpretation)
So, after the whole post we are no closer to knowing if there is life in the cosmos, but what did you expect? Did you think I would tell you some secret here before you saw it blaring out of every news station on the planet? [If you did think that, then thank you so much!] I believe that extraterrestrial life is out there. I even believe that intelligent extraterrestrials are out there, but the universe really is ridiculously, ridiculously vast. It’s going to take a while to find our fellow living beings. In the mean time have faith (which is not advice I thought I would be giving) and keep looking up at the cold distant heavens.
I am combining two important science discoveries from this week into one (small) post. This week astrophysicists working on the Keplar program discovered the three smallest known exoplanets (each of which is smaller than Earth) in orbit around a little red dwarf star. In a completely unrelated field (and scale) of science, biologists in Papua New Guinea discovered the world’s tiniest known vertebrates, two species of miniscule rain forest frogs named Paedophryne amauensis and Paedophryne swiftorum.
Artist's concept of the KOI-961 solar system (Image credit: NASA/JPL-Caltech)
The exoplanets were discovered by a team led by scientists from Caltech who used data from NASA’s mission in conjunction with observations from the Palomar Observatory, (outside San Diego), and the W.M. Keck Observatory (on Mauna Kea in Hawaii). The three planets orbit tiny red dwarf star KOI-961 which has a volume only one-sixth that of our sun (making the star only about 70% bigger than the planet Jupiter). The planets are all very close to their star, and the most distant, takes less than two days to orbit around KOI-961. The three worlds have volumes of 0.78, 0.73 and 0.57 times the radius of Earth.
image credit: Caltech
Red dwarf stars make up four out of five stars in the galaxy, but because they are so small and dim, the Keplar probe has only been assessing a relatively tiny group of red dwarf stars for the possibility of planets. The fact that studying a small sample of red dwarfs already revealed three terrestrial planets strongly suggests that such planets are commonly found around red dwarfs. John Johnson, of NASA’s Exoplanet Science Institute at the California Institute of Technology in Pasadena summarized the data by saying, “This is the tiniest solar system found so far…It’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy.”
An adult Paedophryne amauensis posing on a dime
The discovery of the tiny frogs was made by a team of zoologists in New Guinea led by Chris Austin, a herpetologist trained at LSU. The team was in the forest of New Guinea when they heard a faint metallic song coming from the leaf litter on the forest floor. Unable to see the animal producing the faint chorus of “tink” noises, the biologists grabbed up handfuls of leaf litter into a large transparent bag, and began carefully sorting it–expecting a singing insect to emerge. They were stunned when the miniscule adult frog hopped off a leaf. The fully grown creature only measured 7.7 millimeters (less than one-third of an inch).
Named Paedophryne amauensis the little amphibians are not just the smallest known frogs–they are also believed to be the smallest free-living vertebrates on Earth (supplanting a minute 8mm long translucent Indonesian carp for that title). The frogs do not undergo tadpole metamorphosis in water like other frogs, but are born hopping. They spend their entire lives in the leaf litter where they prey on miniscule arthropods and other invertebrates. A similar species Paedophryne swiftorum was also discovered by the team, although P. swiftorum frogs were nearly a millimeter larger.
In an interview, the team leader Chris Austin said, “We now believe that these creatures aren’t just biological oddities, but instead represent a previously undocumented ecological guild — they occupy a habitat niche that no other vertebrate does.”
An artist's rendition of NASA's MESSENGER spacecraft
Yesterday NASA’s spacecraft MESSENGER entered orbit around Mercury, the least explored of the Solar system’s rocky inner planets. This is the first time a spacecraft has been in orbit around Mercury and it represents a tremendous engineering achievement. Since gravity becomes more intense the closer one comes to the sun, Messenger had to slingshot back and forth among the inner planets for some time in order to accomplish the tricky feat. The spacecraft had to undertake a 4.9 billion mile (about 7.9-billion kilometer) journey to enter orbit around the closest planet to the sun. Of course that hefty mileage only is equal to 0.00083 light years!
Having survived the grueling trip, the spaceship must now carry out its mission in the blistering bath of solar radiation. To survive next to the star, Messenger is equipped with a large sun visor which prevents the little craft from frying like a quail egg.
NO! The Messenger spacecraft is not an old lady playing golf!
Messenger will try to determine the planet’s mineralogical composition and learn about its geological history (the surface of Mercury is reckoned to be one of the oldest in the solar system). The robot probe will fully map Mercury and analyze the planet’s composition. Like Earth (but unlike Mars and Venus) Mercury has an internal magnetic field. Additionally, the tiny world is incredibly dense. In order to learn more about the planet’s core Messenger will measure the extent to which the planet wobbles on its rotational axis. Studying the partially molten interior of Mercury should provide clues about how the planet formed which will help us better understand the creation of all planets (especially in conjunction with the flood of data regarding exoplanets which we are beginning to receive).
Since the craft will be trying to learn the secrets of Mercury’s molten interior, it is worth reflecting on the deity whom the planet is named after. Although he was worshipped as a messenger, a herald, and a god of commerce, the Greco Roman god Hermes/Mercury was also quietly worshipped as a god of the underworld. The Greeks and Romans regarded him as a psychopomp who guided souls down to Hades with his magical staff. Because (like the somewhat similar African traveling god Eshu) Hermes was able to go anywhere at will he was one of the only entities in the Greco Roman pantheon free to enter and leave the underworld.
Although we are not capable like Mercury of going everywhere at our whim, I think it is a tremendous accomplishment to navigate a robot spacecraft into broiling orbit around the innermost planet. That we are using the craft to learn the secrets of the fiery underworld of the swift planet seems like a fitting tribute to the god who was slayer of Argus, giver of charms, messenger, schemer, luck bringer, and patron of travelers and wayfarers (even those voyaging to their last end or to places the ancients could never dream of).
ferrebeekeeper 