The IAU, in the person of Executive Committee member and former General Secretary Thierry Montmerle, wrote the following response to an earlier column, “(Mostly) Thumbs Down on ExoNames.” The response to the article was first posted as a comment on the Many Worlds site, but to ensure that it is seen by readers I am posting the full email now:
We found it quite interesting, since, for once, it concerns the feedback from the astronomers’ community, which is certainly as important for us as the reactions from the public.
We do have a few comments to offer, that may supplement your already rich article.
They are listed below.
Many thanks for you interest in the IAU and in the “NameExoWorlds” contest !
1) The exoplanet community has been involved from the start. IAU Commission C53 set up a Working Group including, among others, Didier Queloz and Geoff Marcy. This Working Group made the recommendation for defining the initial list of 305 confirmed exoplanets for public naming. They also agreed that the names could be given by the public (not by the discoverers or scientists), with the aim of having various names representing different cultures all over the world. Given the results of the contest, it is obvious this goal has been successfully reached.
The discoverers of the named planets have also been contacted at the beginning of the process and most of them expressed that they were enthusiastic about it; they provided comments on their discovery, which were published from the start on the NameExoWorlds web page.
The Working Group also agreed that the public names would never supersede the scientific designations. This has been recalled many times at each step.
2) Astronomy clubs and associations were invited to engage into the contest by voting for the top “most popular” systems (i.e., most interesting in their opinion). As a result, we decided to select the top 20 for naming proposals by the public. The resulting list is remarkably diverse and reflects rather closely the wide range of the present-day “exoplanet science” (restricted to confirmed objects having been studied for many years, not to recent “frontier” objects like the Kepler exoplanet candidates)
3) All the names (including star names) were the subject of 275 argued proposals sent by over 600 registered clubs, then submitted to a public, worldwide vote, and over 500,000 were cast by voters from 180 countries. The contest also generated over 800 articles in 54 countries. Thus the large impact of the contest on the public across the world is undeniable. Also, we have seen in many occasions that the contest gave the opportunity to the astronomical associations to address locally the non-specialist public at large about stars and planets. In this regard, the contest in itself is also a success in arousing a wider interest for astronomy.
4) Whether or not the scientific community uses these names is actually irrelevant, this has never been the purpose of the contest. Professional astronomers still use concurrently common “nicknames” and scientific designations for astronomical objects: alpha CMa and Sirius, M42 and Orion, NGC7293 and the Helix Nebula, M31 and the Andromeda galaxy, etc., but the public certainly prefers to use the nicknames when they exist. The fact is the names approved by the IAU are already quoted in Wikipedia, so the public will very likely use them whenever an opportunity arises.
5) On the other hand, the public names are now officially sanctioned by the IAU and included in the SIMBAD database (and are in the process of being included in other professional databases).
6) We’ll see in the long term whether the names are caught up by the public in general, but in our opinion it will be more a matter of the future scientific interest of the objects themselves (exoplanets and/or stars) than of their public name. There is little doubt that any future press release on HD149026b, for instance, even if written by scientists, will speak about the planet “Smertrios” rather than use the scientific “license plate” designation.
For thinking about the enormity of the canvas of potential suns and exoplanets, I find images like this and what they tell us to be an awkward combination of fascinating and daunting.
This is an image that, using the combined capabilities of NASA’s Hubble and Spitzer space telescopes, shows what is being described as the faintest object, and one of very oldest, ever seen in the early universe. It is a small, low mass, low luminosity and low size proto-galaxy as it existed some 13.4 billion years ago, about 4oo million years after the big bang.
The team has nicknamed the object Tayna, which means “first-born” in Aymara, a language spoken in the Andes and Altiplano regions of South America.
Though Hubble and Spitzer have detected other galaxies that appear to be slightly further away, and thus older, Tayna represents a smaller, fainter class of newly forming galaxies that until now have largely evaded detection. These very dim bodies may offer new insight into the formation and evolution of the first galaxies — the “lighting of the universe” that occurred after several hundred million years of darkness following the big bang and its subsequent explosion of energy.
Detecting and trying to understand these earliest galaxies is somewhat like the drive of paleo-anthropologists to find older and older fossil examples of early man. Each older specimen provides insight into the evolutionary process that created us, just as each discovery of an older, or less developed, early galaxy helps tease out some of the hows and whys of the formation of the universe.
Leopoldo Infante, an astronomer at Pontifical Catholic University of Chile, is the lead author of last week’s Astrophysical Journal article on the faintest early galaxy. He said there is good reason to conclude there were many more of these earliest proto-galaxies than the larger ones at the time, and that they were key in the “reionization” of the universe — the process through which the universe’s early “dark ages” were gradually ended by the formation of more and more luminous stars and galaxies..
But the process of detecting these very early proto-galaxies is only beginning, he said, and will pick up real speed only when the NASA’s James Webb Space Telescope (scheduled to be launched in 2018) is up and operating. The Webb will be able to see considerably further back in time than the Hubble or Spitzer.
Estimates of how many galaxies might exist in the universe are in flux, with recent studies producing results ranging from 100 to 225 billion. On average a galaxy will have some 100 billion stars, giving the universe a low-end estimate of 10,000,000,000,000,000,000,000 stars.
When it comes to planets, a consensus of sorts has formed around the conclusion that in the Milky Way, and perhaps elsewhere, there is on average at least one planet per star. So assuming that the planetary dynamics of our galaxy are similar to those of others, that’s an awful lot of potential exoplanets.
All this has significant implications for the field of exoplanet research.
“We know that basically, planets form at about the same time as their stars from all the leftover dust and gas kicked up,” said Joel Green, Project Scientist at Space Telescope Science Institute’s Office of Public Outreach (STScI.) The Institute operates the science for the Hubble Space Telescope as an international observatory.
“The earliest planets may have been very different kinds of planets because there was not as much metallicity (heavier elements) in those stars. But as soon as you have stars, you have planets.”
He said that in theory, that means that when the very earliest stars formed — during a time when the universe was essentially dark — planets were formed too. “They don’t need a universe of light to form; they need one star.”
The most ancient exoplanet detected so far (PSR B1620-26 b) has had a rather unusual history, first born 12.7 billion years ago outside of a “globular cluster” of stars (a comparatively older, compact group of up to a million old stars, held together by mutual gravitation), it then migrated closer to the cluster and into a rough astrophysical neighborhood. As viewed today, it orbits a pair of burned-out stars in the crowded core of a globular star cluster. It was first identified as a possible planet in 1992 — before the detection of 51 Pegasi b — but it took more than a decade to confirm that it is.
The oldest known exoplanet solar system is Kepler -444, formed 11.2 billion years ago in the Milky Way, itself 13.2 billion years old. Located in the constellation Lyra 116 light-years away, it hosts five rocky planets, all orbiting close to their sun.
The discovery of a solar system with rocky planets of this age (more than twice the age of our solar system’s rocky planet quartet), opens the door to the prospect of an early universe with many more rocky planets than once thought. That means there could be vast numbers of very ancient Earth-like planets out there.
Returning to the faintest protogalaxy, it is described as being comparable in size to the Large Magellanic Cloud (LMC), a very small satellite galaxy of our Milky Way seen in the southern hemisphere. Tayna is rapidly making stars at a rate ten times faster than the LMC, and is likely the growing core of what will evolve into a full-sized galaxy.
This faintest ancient galactic find is part of a discovery of 22 young galaxies at ancient times located nearly at the observable horizon of the universe, research that substantially increases in the number of known very distant galaxies.
“The big unanswered question is how and when did the stars and galaxies turn on to end those Dark Ages,” said Green. “There was a point when they started popping like popcorn. With Hubble we can go back only so far and can’t see anymore, but the James Webb can go significantly further and see back to the Dark Ages.”
Ironically, Infante and his team were able to find the faintest distant galaxy so far without having it be the hardest to see. That’s because they were able to use a technique of observing first proposed by Albert Einstein. As described on the HubbleSite:
The small and faint galaxy was only seen thanks to a natural “magnifying glass” in space. As part of its Frontier Fields program, Hubble observed a massive cluster of galaxies, MACS J0416.1-2403, located roughly 4 billion light-years away and weighing as much as a million billion suns. This giant cluster acts as a powerful natural lens by bending and magnifying the light of far-more-distant objects behind it. Like a zoom lens on a camera, the cluster’s gravity boosts the light of the distant protogalaxy to make it look 20 times brighter than normal. The phenomenon is called gravitational lensing and was proposed by Einstein as part of his General Theory of Relativity.
While gravitational lensing uses a galaxy cluster as its magnifying glass, “micro-lensing” takes advantage of the same physics but uses a single star in our galaxy as the lens. That technique is the only known method capable of discovering planets at truly great distances from the Earth. Radial velocity searches look for planets in our immediate galactic neighborhood, up to 100 light years from Earth, transit photometry can potentially detect planets at a distance of hundreds of light-years, but only micro-lensing can find planets orbiting stars near the center of the galaxy, thousands of light-years away.
And in the spirit of the wonder that microlensing tends to engender, let me leave you with another of those defining astronomical images that are impossible to ignore or forget.
This is the third version of the Hubble Ultra Deep Field, first assembled from 2003-2004 images, upgraded to the Hubble eXtreme Deep Field (XDF) image in 2012 and then enhanced further in 2014 and returned to the original Hubble Ultra Deep Field name. Both the XDF and the 2014 version capture a patch of sky at the center of the original Hubble Ultra Deep Field. That initial effort, which looked back in time approximately 13 billion years, picked up many unintentionally microlensed galaxies.
The newer images feature about 5,500 galaxies even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness of what the human eye can see; just imagine that ratio for a single star or a planet.
So while there undoubtedly are an untold numbers of planets in the field, they will remain hidden for a very long time to come.
When the first exoplanet was identified and confirmed 20 years ago, there was enormous excitement, a sense of historic breakthrough and, with almost parallel intensity, sheer bewilderment. The planet, 51 Pegasi B, was larger than Jupiter yet orbited its parent star in 4 days. In other words, it was much closer to its star than Mercury is to ours and so was extremely hot.
According to theories of the time about planetary formation and solar system organization, a hot Jupiter so close to its sun was impossible. That kind of close-in orbit is where small rocky planets might be found, not Jupiters that belonged much further out and were presumed to always be cold.
That was a soberingly appropriate introduction to the new era of exoplanets, and set the stage for 20 years of surprises and re-evaluations of long held theories and understandings.
While the presence of close-in hot Jupiters certainly remains one of the great puzzles of the exo-planet era, the most consequential exo-planetary revelation has likely been the discovery of many planets larger than Earth and smaller than the next largest planet in our solar system — icy, gaseous Neptune.
These “super-Earths’ and “sub-Neptunes” range greatly in size since Neptune has a radius four times greater than our planet. What’s so surprising about the presence of this class of planets is that they are not just common, they are by far the most frequently detected exoplanets to date.
Perhaps most intriguing of all, however, is their absence in our planetary line-up.
It has long been predicted that the planetary make-up of our solar system would be typical of others, but now we know that is (again) wrong. As Mark Marley, a staff scientist at NASA’s Ames Research Center who studies exoplanets put it, the widespread presence of “super-Earths” elsewhere and their absence in our system “is telling us something quite important.” The work to tease out what that might be has just begun, and will likely keep scientists busy for some time.
“It certainly seems that the universe wants to makes these planets,” Marley told me. “And they’re surprising not only because nobody predicted their vast number but also because they have been intractable – very, very difficult to characterize. It seems like they want to keep their secrets close to the vest.”
How are these planets keeping their secrets – the ingredients of their atmospheres, in particular – from researchers? Because many seem to be surrounded by thick clouds and layers of sooty smog, like Los Angeles on a very bad day. As a result, the spectroscopy normally used to read exoplanet atmospheres and determine what elements and compounds are present is of little use. The instruments can’t see through the thick film
This helps explain why many astronomers and planetary scientists don’t like the term “super-Earths.” The word implies that they are sized-up Earths, but there’s every reason to believe that very few fit into that category. Nonetheless, the name is so compelling that, for now at least, it seems to have stuck – with that addition of “sub-Neptunes.”
Despite the difficulties in characterizing these planets, some progress is being made. Researchers Leslie Rogers of Caltech and Lauren Weiss at Berkeley have separately, for instance, determined which super-Earths and mini-Neptunes are likely to be rocky like Earth and which are likely to be gaseous and icy like Neptune. The cut-off is by no means precise or across-the-board, but it appears that once a planet has a radius more than 1.5 or 1.6 times the size of Earth, it will most likely have a thick gas envelope of hydrogen, helium and sometimes methane and ammonia around it.
Weiss, a Ken & Gloria Levy Graduate Student Fellow, described some other super-Earth/sub-Neptune characteristics that she and others have found. These exoplanets, for instance, very often have nearby companions in the same class. Many of these larger ones (above 1.5 Earth radii) also tend to be fluffy; quite big but not particularly dense. Weiss likens the least dense super-Earths to macarons – a light, French meringue-based confection (that is definitely not a macaroon.)
They may well have cores of iron and some inner rockiness, but they are so light that they have to consist in large part of hydrogen, helium, water and other gases. It is common to find super-Earths and even sub-Neptunes that have much larger diameters than Earth, but have less mass than Earth.
While some of the super-Earths and sub-Neptunes were, and still are being detected using ground-based radial velocity and other techniques, most were found by Kepler. That means the field is very young because that early data came out only a few years ago. But it represents such an important and compelling paradigm shift in astronomy and planetary science that a large and growing contingent of researchers has quickly assembled to search for and study these properly high-profile planets – their orbits, their planetary neighbors, their masses, and now to some extent the make-up of their atmospheres and cores. Some of the work involves observation, some theory and some modeling.
As Mark Marley pointed out, these planets are not giving up their secrets easily. And inevitably, given the great interest and limited data, conclusions and findings will be published that appear strong at the time, but are quickly eclipsed by new information.
Take, for instance, the announced interpretation in 2009, 2012 and 2013 of a sub-Neptune size “water world.” While the papers that introduced the possibility of a very wet exoplanet Gliese 1214b contained caveats, the news stories that went around the world reported that the first water world had apparently been discovered. Exciting news, for sure.
But several years later, it is clear that the water world story was premature. The presence of water had never been confirmed for Gliese 1214b, but rather had been inferred by other limited measurements involving mass, radius, and the absence of spectral data, which were together interpreted to mean the possible, or even probable, presence of a steamy, wet atmosphere.
It still may be the case that the planet has abundant water. But follow-up investigation using the Hubble Space Telescope showed conclusively that the planet was covered in clouds of unknown make-up and origin, and that the presence of massive amounts of water could not be properly inferred from the data at hand.
Zachory Berta-Thompson of MIT was one of the key participants in the Gliese 1214b papers, and he agrees that the evidence today does not point to a water world. “There was a very deep investigation of the GJ 1214b atmosphere with the Hubble, and if water was there it would have been detected,” he said. (The lead author of that paper was Laura Kreidberg of the University of Chicago.)
“We used the data we had when the planet was discovered, and made calculations and inferences that made sense at the time,” Berta-Thompson said. “But the field moves quickly and with the discovery of many other sub-Neptunes, we would draw other conclusions.” Gliese 1214b, he said, is most likely a puffy planet (with an envelope of hydrogen and helium) rather than a water world.
This is not, it should be noted, a knock on the initial paper. If anything, it’s a knock on journalists (of which I have long been one) who highlighted the water world story. But primarily, the Gliese 1214b research is one of numerous examples of the exciting new science of super-Earths and sub-Neptunes playing out at very high speed, with inevitable potholes on a bumpy and terribly hard-to-navigate road.
Many Worlds will continue this discussion of super-Earths and sub-Neptunes on Friday, with an emphasis on thinking about whether they might be conducive or anathema to life.
Throughout the history of science, moments periodically arrive when new fields of knowledge and discovery just explode.
Cosmology was a kind of dream world until Edwin Hubble established that the universe was expanding, and doing so at an ever-faster rate. A far more vibrant and scientific discipline was born. On a more practical level, it was only three decades ago that rudimentary personal computers were still a novelty, and now computer-controlled, self-driving cars are just on the horizon. And not that long ago, genomics and the mapping of the human genome also went into hyperspeed, and turned the mysterious into the well known.
Most frequently, these bursts of scientific energy and progress are the result of technological innovation, coupled with the far-seeing (and often lonely and initially unsupported) labor and insights of men and women who are simply ahead of the curve.
We are at another of those scientific moments right now, and the subject is exoplanets – the billions (or is it billions of billions?) of planets orbiting stars other than our sun.
The 20th anniversary of the breakthrough discovery of the first exoplanet orbiting a sun, 51 Pegasi B, is being celebrated this month with appropriate fanfare. But while exoplanet discovery remains active and planet hunters increasingly skilled and inventive, it is no longer the edgiest frontier.
Now, astronomers, astrophysicists, astrobiologists, planetary scientists, climatologists, heliophysicists and many more are streaming into a field made so enticing, so seemingly fertile by that discovery of the ubiquitousness of exoplanets.
The new goal: Identifying the most compelling mysteries of some of those distant planets, and gradually but inexorably finding ever-more inventive ways to solve them. This is a thrilling task on its own, but the potential prize makes it into quite an historic quest. Because that prize is the identification of extraterrestrial life.
The presence of life beyond Earth is something that humans have dreamed about forever – with a seemingly intuitive sense that there just had to be other planets out there, and that it made equal sense that some of them supported life. Hollywood was on to this long ago, but now we have the beginning technology and fast-growing knowledge to transform that intuitive sense of life out there into a working science.
Already the masses and orbits of several thousand exoplanets have been measured. Some planets have been identified as rocky like Earth (as opposed to gaseous like Jupiter.) Some have been found in what the field calls “habitable zones” – regions around distant suns where liquid water could plausibly run on a surface –as it does on Earth and once did on Mars. And some exoplanets have even been determined to have specific compounds – carbon dioxide, water, methane, even oxygen – in their atmospheres.
This and more is what I will be exploring, describing, hopefully bringing to life through an on-going examination of this emerging field of science and the inventive scientists working to understand planets and solar systems many light-years away. Theirs is a daunting task for sure, and progress may be halting. But many scientists are convinced that the goal is entirely within reach – that based on discoveries already made, the essential dynamics and characteristics of very different kinds of planets and solar systems are knowable.
Thus the name of this offering: “Many Worlds.”
I was first introduced to, and captivated by, this cosmic search in a class for space journalists taught by scientists including Sara Seager, a dynamic young professor of physics and planetary science at M.I.T., a subsequently-selected MacArthur “genius,” and a pioneer in the field not of discovering exoplanets, but of characterizing them and their atmospheres.
And based on her theorizing and the observations of many others, she was convinced that this characterizing would lead to the discovery of very distant extraterrestrial life, or at least to the discovery of planetary signatures that make the presence of life highly probable. Just this week, she predicted the discovery could take place within a decade.
It was in 2010 that she began her book “Exoplanet Atmospheres” with the statement: “A new era in planetary science is upon us.” I would take it further: A new era has arrived in the human drive to understand the universe and our place in it.
Exoplanets and their solar systems are a magnet to young scientists, says Paul Hertz, the head of NASA’s Astrophysics Division. Almost a third of the papers presented at astronomy conferences these days involve exoplanets, he said, and “it’s hard to find scientists in our field under thirty not working on exoplanets.” Go to a major geology conference, or a planetary science meeting, and much the same will be true.
And why not? I think of this moment as akin to the time in the 17th century when early microscopes revealed a universe of life never before seen. So many new questions to ask, so many discoveries to make, so much exciting and ultimately world-changing science ahead.
But the challenge of characterizing exoplanets and some day identifying signs of life does not lend itself to the kind of solitary or small group work that characterized microbiology (think the breakthrough NASA Kepler mission and the large team needed to make it reality and to analyze its results.) Not only does it require costly observatories and telescopes and spectrometers, but it also needs the expertise that scientists from different fields can bring to the task – rather like the effort to map the human genome.
That is the organizing logic of astrobiology – the more general hunt for life elsewhere in our solar system and far beyond, alongside the search for clues into how life may have started on our planet. NASA is eager to encourage that same spirit in the more specific but nonetheless equally sprawling exploration of exoplanets, their atmospheres, their physical makeup, their climates, their suns, their neighborhoods.
The result was the creation this summer of the the Nexus for Exoplanet System Science (NExSS), a group that will be led by 17 teams of scientists from around the country already working on some aspect of the rich exoplanet opportunity. The group was selected from teams that had applied for grants from NASA’s Astrobiology Institute, an arm of its larger NASA Astrobiology Program, as well as other NASA programs in the Planetary Sciences, Astrophysics and Astronomy divisions.
Their mandate is to spark new approaches in the effort to understand exoplanets by identifying areas without consensus in the broader community, and then fostering collaborations here and abroad to address those issues.
“Many Worlds” grew out of the NExSS initiative, and will chronicle and explain the efforts of some team members as they explore how exo-plants and exo-creatures might be detected; what can be learned from afar about the surfaces and cores of exoplanets and how both play into the possibility of faraway life; the presence and dynamics of exo-weather, what we can learn about exoplanets from our own planet and solar system, and so much more.
A few of the teams are small, but many are quite large, established and mature – perhaps most especially the Virtual Planetary Laboratory at the University of Washington, and run by Victoria Meadows. Since 2001, the virtual lab has collaborated with researchers representing many disciplines, and from as many as 20 institutions, to understand what factors might best predict whether an exoplanet harbors life, using Earth as a model.
But just as I will be venturing beyond NExSS in my writing about this new era of exploration, so too will NExSS be open to the involvement of other scientists in the field. The original group has been tasked with identifying an agenda of sorts for NASA exoplanet missions and efforts ahead. But its aim is to be inclusive and its conclusions and recommendations will only be as useful and important as the exoplanet community writ large determines them to be.
This is a moment pregnant with promise. Systematically investigating exoplanets and their environs is an engine for discovery and a pathway into that largest question of whether or not we are alone in the universe.
Will scientists some day find worlds where donkeys talk and pigs can fly (as at least one “everything is possible” philosopher has posited)? Unlikely.
But just as microscopes and the scientists using them led to the science of microbiology and most of modern medicine, so too are our orbiting observatories, Earth-based telescopes and the scientists who analyze their results are regularly opening up a world of myriad and often surprising marvels.
This blog is being hosted by Knowinnovation Inc. and is supported by the Lunar and Planetary Institute (LPI). LPI is operated by the Universities Space Research Association (USRA) under a cooperative agreement with NASA. The purpose of this blog is to communicate the work of the Nexus for Exoplanet Systems Science (NExSS). Any opinions, findings, and conclusions or recommendations expressed on this blog or its comments are those of the author(s) and do not necessarily reflect the views of NASA.