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What could we talk about today other than NASA’s stunning announcement of a “nearby” star system with seven Earthlike planets? Three of these rocky worlds are comfortably in the so-called habitable zone where liquid water exists and earthlike life could be possible. The star is TRAPPIST-1, a small-batch artisanal microstar with only a tenth the mass of the sun. It glistens a salmon hue and is half the temperature of the sun (and emits far less energy). Fortunately, all of its planets are much closer to the pink dwarf than Earth is to the sun, and so the middle worlds could be surprisingly clement. These planets are close to each other and sometimes appear in each other’s skies larger than the moon looks to us! The coral sun would be dimmer… but 3 times larger in the sky! It is a pretty compelling picture! Imagine sauntering along the foamy beaches of one of these worlds and looking up into a pool-table sky filled with Earth sized worlds and a cozy Tiffany lamp in the sky emitting titian-tinted light.
I am leaving out the details we know about the seven worlds because we don’t know much other than approximate mass (approximately earthsized!) and the ludicrously short length of their years. Since the inner three worlds are tidally locked they may have extreme weather or bizarre endless nights or be hot like Venus (or bare like Mercury).
Trappist1 is 40 light-years (235 trillion miles) from Earth in the constellation Aquarius. It seems like an excellent candidate for one of those near-light speed microdarts that Steven Hawking and that weird Russian billionaire have been talking about (while we tinker with our spaceark and debate manifest destiny and space ethics). However, before we mount any interstellar expeditions to Trappist1 (an anchoritic-sounding name which I just cannot get over) we will be learning real things about these planets from the James Webb space telescope when it launches in 2018–assuming we don’t abandon that mission to gaze at our navels and pray to imaginary gods and build dumb-ass walls.
Today’s announcement is arguably the most astonishing thing I have heard from the astronomy community in my lifetime (and we have learned about treasure star collisions and super-dense micro galaxies and Hanny’s Voorwerp). Ferrebeekeeper will keep you posted on news as it comes trickling out, but in the meantime let’s all pause for a moment and think about that alien beach with a giant balmy peach sun…. Ahh! I know where I want to escape to next February!
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!
Previously discovered dwarf satellite galaxies (in blue) and the newly discovered candidates (in red) (Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler (KIPAC/SLAC))
We have some new galactic neighbors! Well, actually maybe “new” is not the right term: they have been there for a long time but we only just now noticed. Astronomers are reporting the discovery of nine dwarf satellite galaxies orbiting the Milky Way like remoras stuck to a cosmic shark. These nine miniature galaxies are additional to the well-known Large and Small Magellanic Clouds—two dwarf galaxies which are located right next to the Milky Way (being respectively 160,000 and 200,000 light years away).
The new dwarf galaxies were discovered by a team of astronomers poring over data recovered from the Dark Energy Survey (a super-high resolution digital array which is part of the Victor M Blanco telescope in the Andes). The closest is a mere 97,000 light years from the Milky Way whereas the farthest lies 1.2 million light years away from us. The dwarf galaxies are a billion times fainter than the Milky Way. They are made up of millions (or hundreds of millions or even billions) of stars but are insignificant in size compared to the hundreds of billions of stars which constitute a true galaxy. Scientists believe that there are hundreds of similar miniature galaxies and pseudo-galaxies near the Milky Way, but they are dark and difficult to find (comparitively speaking).
The Large and Small Magellanic Clouds, near which the satellites were found. (image from European Southern Observatory)
I have been saying “dwarf galaxies” because I like the way it sounds (like the new galaxies live together in the woods in a little hut and work in the mines!), but actually only three of the new companions are definitely dwarf galaxies. The remaining six structures may be dwarf galaxies or they may merely be globular clusters—a far less euphonic phrase which indicates a group of stars which orbits a galactic core as a satellite. Unlike globular clusters, dwarf galaxies are held together by the gravitational mass of large quantities of dark matter (um, assuming it actually exists). Indeed dwarf galaxies seem to contain far greater quantities of dark matter than actual galaxies. This makes the newly discovered galactic neighbors a potentially useful focus for studying the properties of dark matter and refining our model of the universe.
Ceres (Jean-Antoine Watteau, 1717-1718, oil on canvas)
In my many posts about art and painting, I have shamefully slighted the wonderful 18th century. Here is a masterpiece by one of the greatest painters of that era, Jean-Antoine Watteau, whose career was all too brief. Watteau bridged the gap between Baroque and Rococo by bringing the naturalistic color and movement of Correggio to the rigorous classical tradition of great French masters such as Poussin and Lorrain. This beautifully painted oval composition portrays the fertility goddess Ceres shimmering among the lambent clouds in the long pink evenings of summer. Her garb of gold and shell color perfectly suits the joyous abundance of the season. Around her, youths are gathering the precious life-giving wheat while the astrological beasts of the summer sky gambol at her side.
Artist’s conception of the Dawn spacecraft
Of course I did not just pull this choice of subjects out of some crazy 18th century hat! As I write this, the NASA spacecraft Dawn is hurtling through the asteroid belt toward the dwarf planet Ceres, the largest body in the asteroid belt. Ceres (the dwarf planet) is located in the strange region between Mars and Jupiter. It is large enough to be spherical due to its own gravity but something seems to have gone horribly wrong there. It appears to be the shattered core of a world which either never quite formed or which was destroyed during the making—a miscarriage four and a half billion years old. Scientists have speculated about what the little world is composed of and how it was created, but telescopes have only revealed so much, and no spacecraft has visited prior to Dawn. This is a time of true exploration like the 18th century! Already Dawn’s cameras have spotted bizarre ultra-bright reflections from Ceres. Are they sheets of ice or metal…something else? We will have to wait till the probe enters orbit in April to find out, but I am excited to learn more about the formation of Ceres (which is to say the formation of the solar system) and to finally solve some of the mysteries of this under-appreciated heavenly neighbor.
This image of Ceres was taken by NASA’s Dawn spacecraft on Feb. 19 from a distance of nearly 46,000 kilometers (29,000 miles)
Of course I am also heartily sick of this endless disappointing winter. The sooner Ceres (the allegorical figure of abundance and warmth) brings life back to Brooklyn, the happier I will be. Let’s all keep our fingers crossed for exciting news from space and for the return of life and growth here on (the north part of) Earth after a long winter. Also anybody who wishes for the return of classical beauty and allegorical subtlety in the dismal world of ill-conceived & poorly-executed contemporary art will have my heartfelt appreciation and best wishes!
Ancient Greek stone carving of the goddess Ceres with poppies, shafts of wheat, and snakes
Between giant planets and small stars exists a bizarre class of heavenly objects known as brown dwarfs. Brown dwarfs are not massive enough to fuse hydrogen elements together as do main sequence stars like the sun, however brown dwarfs larger than 13 Jovian masses are believed to fuse deuterium atoms and large brown dwarfs (65 Jovian masses and up) are believed to fuse lithium. Since brown dwarfs can be very much like planets or like stars, there is a specific definition to describe the objects: a brown dwarf must have experienced some sort of nuclear fusion as a result of mass and temperature, however it cannot have fused all of its lithium (or it is considered a star or stellar fragment). A stellar physicist reading this blog might object that medium and large stars have some lithium present in their outer atmosphere, or that a very young white dwarf could still have some unused lithium present, or even that an old heavy brown dwarf could have fused all of its lithium. That physicist would be correct: she deserves some cookies and a pat on the head for poking holes in unnecessarily simple definitions.
Various Classifications of Brown Dwarfs
Brown dwarfs were theorized to exist in the 1960s, but no astronomer managed to discover one until 1988 when a team of University of California astronomers who were studying white dwarfs found a bizarrely cool red spectral signature for a faint companion to the star GD 165. Since then many brown dwarfs have been discovered and sorted into the major types M, L, T, and Y. They occupy a strange ambiguous area at the bottom of the Hertzsprung-Russell diagram—objects which are luminous and massive in comparison to everything else but tiny and dim compared to real stars.
There are some planets which are known to orbit brown dwarfs and there also brown dwarfs known to orbit true stars. It is beginning to seem that there a great many brown dwarfs out there: perhaps they are as numerous as true stars (or maybe they are even more common than that). Since they are hard to detect, scientists do not have a very accurate assay of their frequency in the universe. The question bears somewhat on our understanding of the universe–since a great deal of matter is not accounted for.
An artist’s conception of a brown dwarf seem from a closely orbiting planet
My mind keeps returning to the fact that some brown dwarfs have planetary systems. Imagine these melancholic twilight ice worlds forever orbiting a dim glow which will never blaze into a true sun. It is a melancholy picture, but not without a certain beauty.
A Brown Dwarf with Planet and Moon (painting by Lynette Cook from fineartamerica.com)
Exciting news from the heavens! Today NASA has reported that the Kepler mission has discovered 3 new planets in the habitable zones of two distant stars. Of the thousands of worlds so far discovered, these three are most likely to be habitable. Best of all the planets are crazy!
Kepler is a NASA space telescope which was launched on March, 2009. It makes use of an incredibly sensitive photometer to simultaneously & incessantly monitor the brightness of over 150,000 nearby stars. The brightness of a star dims slightly whenever an exoplanet transits between it and Kepler. Thanks to Kepler’s inhuman vigilance and robotic ability to perceive nearly imperceptible light changes, we are now discovering thousands of new planets, although most of them are Jovian sized gas worlds.
Kepler Space Telescope
The three worlds reported today lie in the habitable zone—the region around a star where water exists in a liquid form (as it does here on beautiful Earth). Two of the newly discovered habitable zone planets are in a five planet system orbiting a dwarf star just two-thirds the size of the sun which lies 1,200 light years from Earth. Here is a diagram of the Kepler 62 system.
Kepler 62 System (Art by NASA)
Of these five worlds, two lie in the habitable zone, Kepler 62f and Kepler 62e. Kepler 62 F is most likely a rocky planet and is only 40 percent larger than Earth. It has an orbit which last 267 (Earth) days. So far it is the smallest exoplanet found in the habitable zone. The star it orbits is 7 billion years old (as opposed to the sun which is four and a half billion years old) so life would have had plenty of time to develop. The other habitable zone planet in the Kepler 62 system, Kepler 62e is probably about 60% larger than our planet. It is somewhat closer to the star and astrophysicists speculate it may be a water world of deep oceans.
No! Not that sort of Waterworld!
The other new exoplanet Kepler-69c appears to orbit a star very similar to Earth’s sun. It orbits at the inward edge of the habitable zone (nearing where Venus is in our solar system) so it may be hot. The planet is estimated to be about 70% larger than Earth, and is also thought to be a water world with oceans thousands of kilometers deep. I am finding it impossible not to imagine those vast oceans filled with asbestos shelled sea-turtles the size of dump trucks, huge shoals of thermophile micro-squid, and burning-hot chartreuse uber-penguins, but if any life is actually on Kepler-69c, it is probably extremely different from Earth life.
I understand why they are green and have gills, but why are they inside gelatin capsules? (DC Comics)
Of course Kepler can only find these planets; it is unable to observe very much about them. In order to do that, humankind will need some sort of huge amazing super telescope. Speaking of which, tune in next week when I write about humankind’s plans for building a huge amazing super telescope in the Chilean Andes!
The Dwarf Planet Haumea
Haumea is a dwarf planet located in the Kuiper belt. The little planetoid was discovered in December 2004 by a team of Caltech astronomers. It is about a third the size of Pluto. The team initially called it “Santa” but, in keeping with the IAU’s naming convention for Kuiper belt objects they eventually named the worldlet after a matronly fertility goddess from Hawaiian mythology.
Artist’s conception of Haumea and its pink spot
Although Haumea is typical of other dwarf planets in the Oort cloud in that it is a hunk of rock covered with ice, there are a couple of very unique things about the body. Most notably Haumea is shaped like a lozenge (as opposed to being mostly spherical like other planets). Astronomers believe that Haumea has sufficient gravity to overcome the compressive strength of its material. In other words it chould be approximately spherical, however the planet is rotating with such velocity that it has become spindle shaped—like a water balloon thrown in a rifling spiral.
The extreme rapidity of Haumea’s rotation is its other defining characteristic. It rotates more rapidly than any planetlike object with a diameter greater than 100 kilometers. Haumea rotates completely every 3.9 hours so days there are incredibly short (although its huge orbit takes 283 years to complete—so years are long). It is believed that Haumea’s breakneck spin comes from a titanic collision with some other Oort belt object. Haumea’s two dinky moons were probably also created by the impact. Haumea has a large red spot on it–perhaps because of the presence of minerals–or the fractured perturbance left by an impact.
Artist's Interpretation of Sedna (Credit: Gemini artwork by Jon Lomberg)
After the discovery of Pluto in 1930, there was a long hiatus in discovering objects of comparable size. Then in 2003, a team of astronomers led by Mike Brown of Caltech discovered a distant icy sphere which was quickly heralded as “the tenth planet.” Mike Brown announced the discovery on his website along with his team’s rationale for naming the object. He wrote “Our newly discovered object is the coldest most distant place known in the Solar System, so we feel it is appropriate to name it in honor of Sedna, the Inuit goddess of the sea, who is thought to live at the bottom of the frigid Arctic Ocean.
It turns out that Sedna is only one of many similar snowball-like planetoids beyond Neptune. In fact, Ferrebeekeeper has already described the dwarf planet Eris (named after the Greek goddess of Strife) which is the largest currently known Kuiper belt object. Sedna was the first to be discovered since Pluto and it sparked a debate about such objects which ultimately resulted in Pluto’s downgrade to dwarf planet. Sedna also has some unique features which make it remarkable in its own right.
The orbit of Sedna (red) set against the orbits of Jupiter (orange), Saturn (yellow), Uranus (green), Neptune (blue), and Pluto (purple)
Sedna takes 11,400 years to complete its orbit around the sun and its bizarre highly elliptical orbit has given rise to much conjecture among astronomers. Although some astronomers believe it was scattered into a skewed orbit by the gravitational influence of Neptune, other astronomers believe it originated in the inner Oort cloud and was never close enough to Neptune to be affected by the giant’s gravity. Some scientists speculate that its lengthy orbit may have been caused by a passing star (perhaps from the sun’s birth cluster). A few theorists have gone one step further and conjectured that Sedna is from a different solar system and was captured by our Sun billions of years ago. A final school contends that Sedna is evidence of an unknown giant planet somewhere in the depths of space (!).
A photo of Sedna taken from a powerful telescope on Earth
We don’t know much about Sedna except that is probably 1,200–1,600 km in diameter and that its surface is extremely red. After Mars, Sedna is one of the reddest astronomical objects in our solar system. This color comes from the profusion of tholins covering the methane and nitrogen ice of which the little world is formed. Tholins are large, complex organic molecules created by the interaction of ultraviolet light on methane and other simple hydrocarbons. It is believed that early Earth (prior to obtaining an oxidizing atmosphere) was rich in Tholins and they are one of the precursors to the rise of life.
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.”
ferrebeekeeper 