Cloudy With a Chance of Sunshine: Astronomers Study Weather on Distant Exoplanets

An artist's rendering of the possible weather and atmospheric circulation patterns on hot Jupiters. A new research by a team of astronomers that was based on data taken with NASA's Kepler space telescope, studied the phase variations that occur as different portions of these planets are illuminated by their host stars as seen from our vantage point here on Earth, providing detailed insights the daily weather patterns on these distant alien worlds. Image Credit: Lisa Esteves/University of Toronto.

An artist’s rendering of the possible weather and atmospheric circulation patterns on hot Jupiters. A new research by a team of astronomers that was based on data taken with NASA’s Kepler space telescope, studied the phase variations that occur as different portions of these planets are illuminated by their host stars as seen from our vantage point here on Earth, providing detailed insights the daily weather patterns on these distant alien worlds. Image Credit: Lisa Esteves/University of Toronto.

Daily weather forecasts are an integral part of modern life in every part of the world. Besides informing us for upcoming short-term weather conditions, these forecasts provide an essential understanding of the Earth’s overall climate over longer timescales. But what about the weather on extrasolar worlds? Out of the more than a thousand exoplanets that have been discovered to date, scientists only managed to create crude and rudimentary weather maps for just a handful of them. A new study, based on data from NASA’s Kepler space telescope and recently published by an international research team, comes to substantially increase our understanding of exoplanet atmospheres by presenting evidence of the daily weather cycles for more than a dozen planets around other stars.

Even though the first extrasolar world was discovered more than 20 years ago, the field of exoplanetary research has been completely transformed in the last five years specifically, with the launch of NASA’s Kepler space telescope in 2009. Staring constantly at a field in the sky containing 150,000 stars, Kepler has already discovered more than a thousand confirmed exoplanets as well as more than 4,500 exoplanet candidates to date with the use of the transit method, while also revealing the previously unimagined great abundance of exoplanets in the galaxy. As has already been detailed in previous AmericaSpace articles, the treasure trove of data already returned by Kepler has allowed astronomers to not only detect the presence of exoplanets but to start characterising them in detail as well, with the help of transit spectroscopy that has been conducted with other orbiting observatories like NASA’s Spitzer and Hubble space telescopes. More specifically, when an extrasolar planet happens to cross the face of its star as seen by our line of sight here on Earth, it causes a small dip in the star’s brightness which is proportional to the size of the exoplanet itself. If that planet also happens to have an atmosphere, the latter will absorb some of the star’s light in certain wavelengths during its transit, resulting in a wavelength-dependent transit depth, better known as a transmission spectrum. By studying this spectrum of the combined star-planet light, astronomers have extracted detailed information about the chemical composition, temperature, density, and overall dynamics for dozens of extrasolar worlds.

With the use of transit spectroscopy, astronomers can gain important information about a planet’s physical and chemical properties, as it passes in front and behind of its host star. Image Credit: Sara Seager

With the use of transit spectroscopy, astronomers can gain important information about a planet’s physical and chemical properties, as it passes in front and behind of its host star. Image Credit: Sara Seager

Another important tool in the study of exoplanets is the analysis of their phase curve. As is the case with the Moon and the inferior planets of the Solar System, Mercury and Venus, which display a full range of phases from new to full as seen from our vantage point, exoplanets can also exhibit phase variations during their orbital paths around their host stars. The analysis of these variations can yield great insights to the atmospheric and weather conditions on exoplanets through the study of their albedo (the amount of stellar light that is reflected from the exoplanet atmosphere back into space) and their flux ratios (the ratio of the planet’s reflected light to that emitted by its host star).

An international team of astronomers, led by Lisa Esteves, an exoplanet researcher and PhD student at the University of Toronto’s Department of Astronomy and Astrophysics in Canada, conducted just such a comprehensive analysis for a total of 14 “hot Jupiter”-type exoplanets, based on four years’ worth of data gathered by the Kepler space telescope. These types of planets are large and massive gas giants similar to Jupiter, that lie in orbits that are considerably closer to their host stars than that of Mercury in our own Solar System, resulting in scorching-hot temperatures at their cloud tops that can typically exceed 1,500 K. Being the first types of extrasolar worlds to be discovered in the 1990s, hot Jupiters have been studied extensively by astronomers through the years, who have managed to infer many details regarding their atmospheric chemical abundances as well as their possible internal compositions. By carefully analysing the light curves of the selected exoplanets in their study, Esteves’ team was able to now construct the first-ever detailed atmospheric circulation models, which in turn helped the researchers to provide weather reports for these types of extrasolar worlds. “We determined the weather on these alien worlds by measuring changes as the planets circle their host stars, and identifying the day-night cycle,” says Esteves. “We traced each of them going through a cycle of phases in which different portions of the planet are illuminated by its star, from fully lit to completely dark.”

One defining characteristic of hot Jupiters is that, due to their proximity to their host stars, they are tidally locked in their orbits similar to the way the Moon is tidally locked in its orbit around Earth, which means they present the same face toward their star as they revolve around it. Based on independent observations of hot Jupiters by other researchers, Esteves’ team hypothesize in their study that this type of orbital motion plays a defining role in the shaping of the weather and climate on these worlds. “Close-in planets, such as those in our sample, are expected to be tidally locked and will therefore rotate prograde, with the planet’s night-side moving in the direction of orbital motion,” write the researchers in their study which was published earlier this month in The Astrophysical Journal. “With this assumption, the planet’s evening-side will be visible during the first half of the orbit [before being eclipsed by the star as the planet moves behind it], while the morning-side will be more visible in the second (post-eclipse), regardless of on-sky orientation. Therefore, if atmospheric circulation moves in the direction of rotation, winds would transport energy from the substellar point [the location on an exoplanet over which its host star would appear to be in the zenith] towards the planet’s evening-side and then onwards towards the morning-side.”

This atmospheric circulation in effect results in a particular daily weather pattern, where the planet is covered with clouds in its night side due to the lower temperatures that dominate the latter relative to the day side, which then dissipate during the day from the extreme heat of the nearby star, thus leaving the local afternoons in sunshine and completely cloud-free. “As the winds continue to transport the clouds to the day side, they heat up and dissipate, leaving the afternoon sky cloud-free,” says Esteves. “These winds also push the hot air eastward from the meridian, where it is the middle of the day, resulting in higher temperatures in the afternoon.”

Hot Jupiters lie so close to their host stars that become tidally locked in their orbits, while always presenting the same face toward their star at any given time. This tidal locking plays a defining role in the shaping of weather on these alien worlds. Image Credit: NASA/ESA

Hot Jupiters lie so close to their host stars that become tidally locked in their orbits, while always presenting the same face toward their star at any given time. This tidal locking plays a defining role in the shaping of weather on these alien worlds. Image Credit: NASA/ESA

In addition, the researchers’ results suggested a possible link between the surface temperature and thermal emission of hot Jupiters and their atmospheric circulation patterns. More specifically, four of the examined exoplanets in the team’s study which had a comparatively lower temperature (below 2,300 K) exhibited an excess brightness in their day side—a typical characteristic for planets that were mostly illuminated by reflected star light. Yet two other exoplanets in the team’s sample, whose temperatures were above 2,700 K, exhibited an excess brightness that was dominant during the evening, resulting more from the planets’ own internal heat than from the reflected light from the host star. “By comparing the planets’ previously determined temperatures to the phase cycle measurements provided by Kepler, we found that the excess brightness on the morning side is most likely generated by reflected starlight,” explains Esteves. “The [cooler] four planets are not hot enough to generate this excess light through thermal emission. The excess light seen on the two very hot planets can be explained by thermal emission. A likely explanation is that on these two planets the winds are moving heat towards the evening side, resulting in the excess brightness.”

The study by Esteves’ team is the latest in the long line of research that has been conducted in recent years regarding the atmospheric dynamics on exoplanets, with the help of various space-based telescopes like Spitzer and Hubble. Yet, as fascinating as these latest findings are, they have nevertheless marked the limit of Kepler’s observing capabilities. “The detection of light from these planets hundreds to thousands of light years away is on its own remarkable,” comments Dr. Ernst de Mooij, a Research Fellow at Queen’s University Belfast in the UK and member of Esteves’ team. “But when we consider that phase cycle variations can be up to 100,000 times fainter than the host star, these detections become truly astonishing.”

More detailed views on the weather on distant alien worlds will have to wait the next generation of space-based observatories, like the James Webb Space Telescope, which are scheduled to launch within the next few years. “Upcoming space missions should reveal many more small planets around bright stars that will make great targets for detailed studies,” says Dr. Ray Jayawardhana, a professor of astrophysics at the York University in Toronto, Canada, and co-author of the recent study by Esteves’ team. “Someday soon we hope to be talking about weather reports for alien worlds not much bigger than Earth, and to be making comparisons with our home planet.”

Exoplanetary research has come a long way since the days of the first exoplanet discoveries more than 20 years ago. Given the great strides that have taken place in this exciting field of astronomical study in recent years, it is not unreasonable to assume that sometime in the not too distant future, detailed exoplanetary weather reports might be as common in the same way that the detections of new exoplanets are today.

An overview of previous weather studies of hot Jupiters, as of 2013. Video Credit: NASA

 

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27 comments to Cloudy With a Chance of Sunshine: Astronomers Study Weather on Distant Exoplanets

  • Gary Church

    I have read the main limiting factors in telescope power are the weight of the mirror warping under the influence of gravity thus restricting the size and the atmosphere on Earth. Neither applied to the Hubble because it could only be made so big for launch from Earth.

    I would like to see an article describing a space telescope at a libration point made to a scale practical with present technology. A system much larger than the present Webb telescope being built. The SLS might be able to lift a disk-shaped fairing containing a mirror considerably larger than the stage diameter. But how large is feasible? 40 or 50 feet? And would mounting several of these telescopes on a giant frame be possible to make a super telescope array in space?

    The “lollipop” payload is interesting to me because a simple metal disc is essentially what a nuclear pulse propulsion engine is. The metal must be “opaque” to the radiation it is being exposed to momentarily during the pulse and also of course withstand the forces involved. The operating principle being it will not have time to melt in that fraction of a second encompassing the pulse event. A thin compound disc would mass several hundred tons and stacking the thin discs of a few dozen tons each would result in a working engine- but would require rather low power and inefficient bombs. This would also avoid the other option- welding slices of pie together in space to build a disc. The alternate type of engine to launch from Earth is the Medusa concept- a giant parachute- and this would also be limited in efficiency and even more so in durability.

    Really large mirrors cannot be lifted from the surface of the Earth- they would have to be fabricated on the Moon where there would be no aerodynamic diameter limitations at all in launching them. How big could they be? That is a whole different situation because the lunar gravity would limit the size at some point just like on Earth but launching one into space would remove even that and the mirror could be hundreds of feet in diameter.

    And what holds true for mirrors holds true for discs- truly immense titanium discs could be fabricated on the Moon and take-off from the surface using the optimum size of H-bomb with an Isp in the tens of thousands. Such spaceships would allow for the exploration of the outer solar system with missions lasting only a few years and carrying multi-thousand ton payloads.

    • “I have read the main limiting factors in telescope power are the weight of the mirror warping under the influence of gravity thus restricting the size and the atmosphere on Earth.”

      I’m afraid that your information is hopelessly outdated. This was certainly the case many decades ago with the old telescope technology which is why the 200-inch Hale Telescope was the largest telescope in the world for 45 years. Thick monolithic mirrors any larger than this were incapable of supporting their own weight and sagged out of shape (a lesson that Soviet astronomers learned the hard way when they built a 235-inch telescope in the Crimea in the 1970s). The effects of the atmosphere limiting the quality of seeing was also one of the arguments made for space telescopes decades ago. But technology has advanced and trashed all of these arguments decades ago.

      The latest generation of large telescopes no longer rely on the structure of the mirror to maintain the shape of their optical surface. They are either thin monolithic mirrors or (more commonly today) arrays of thin mirrors that use active computer feedback to control actuators on the mirror supports that maintain the shape of the telescope’s optical surface as the telescopes slew to different parts of the sky. As a result, ground-based telescopes have grown to diameters of 10 meters (409 inches) with even larger telescopes under development. At least for operations at visible wavelengths and infrared window bands, there is no longer any need for large telescopes to be based in space (this is one of the reasons why NASA’s new JWST has been optimized to work at IR wavelengths).

      As for the issues surrounding atmospheric seeing, huge gains have been made in adaptive optics (AO) over the last quarter of a century to remove distortions caused by the atmosphere. In AO, sensors determine how the incoming wavefront has been distorted by its passage through the atmosphere and a computer controlled optical element has its shaped altered hundreds of times each second to correct for these distortions. While the early AO systems were limited to operating over small fields of view (FOV) in the infrared, they have been steadily improving to the point where diffraction-limited imaging (on the order of tens of milliarc seconds) is possible over increasingly larger FOVs into visible wavelengths. Between the larger mirrors and improving AO technology, ground-based telescopes regularly outperform Hubble at visible and near-IR wavelengths (which is why Hubble has increasingly been used to make observations at wavelengths that do not penetrate the atmosphere e.g. IR and UV or secure views over fairly large FOVs). The bottom line is that many of the original arguments for expensive space-based telescopes like Hubble are simply no longer valid and it is cheaper to use ground-based telescopes with equal or better performance instead.

      While large space-based telescopes that operate at IR and other wavelengths that do not penetrate Earth’s atmosphere certainly have their place, they do not use monolithic mirrors any longer but employ segmented mirror arrays instead like JWST. If still larger space telescopes are ever to be built, it would be cheaper to launch the material from Earth and assemble them in space rather than create a brand new infrastructure on the lunar surface to mine materials and manufacture precision optics (which has never been done off world). For applications that would require ultra-high resolution at IR to visible wavelengths (e.g. imaging Earth-size extrasolar planets or black holes in the cores of distant galaxies), it is true that this is impractical to do from the Earth’s surface. But building monolithic mirrors hundreds or even thousands of meter across is not require either. Astronomers envision the use of sparse aperture telescopes akin to that used in VLBI radio observations. In this case an array of independently controlled small-aperture telescopes fly in formation to create a synthetic aperture kilometers or more across. Once again, it would be easier and cheaper to build such space telescopes on Earth and launch them into space.

      I’m afraid that your arguments for establishing a lunar resource extraction infrastructure to support the construction of large telescopes simply has no merit any longer given the advances in optical technology over the last three or four decades. There are better reasons to be exploiting lunar resources at some point in the future.

      • Gary Church

        http://iloa.org/index.htm

        They disagree with you Andrew.

        Prof. U.R. Rao, of Bangalore, India: Chairman of the Governing Council of the Physical Research Laboratory in Ahmedabad. Former chairman of the Indian Space Research Organization (ISRO).

        Ziyuan Ouyang, of Beijing, China: Chief scientist of the Chinese Lunar Exploration Program (Chang’e program).

        Jean-Luc Josset, of Neuchâtel, Switzerland: CEO of Space Exploration Institute. Principle Investigator of AMIE Camera which orbited the Moon aboard the ESA SMART-1 spacecraft.

        Christian Veillet, of Tucson, AZ: Astronomer. Director Of Large Binocular Telescope Observatory, Former Director of Canada France Hawaii Telescope.

        Maohai Huang, of Beijing, China: Professor of Astrophysics at NAOC. Made 6 trips to Antarctica for Astrophysical research. Assistant of Chief Lunar Scientist Ziyuan Ouyang. PhD Graduate of BU.

        Yuki Takahashi, of Berkeley, California: Astrophysicist, graduate of UC Berkeley, PhD research conducted on Astronomy from Antarctica. Currently working as a Radio Frequency engineer at SpaceX.

        David Schrunk, of Poway, California: Medical Doctor. Author of The Moon: Resources, Future Development, and Settlement.

        Christian Sallaberger of Toronto, Canada: Former Vice President & Director of Space Operations at MDA Space Missions.

        Shawna Pandya of Edmonton, Canada: Medical student at University of Alberta. ISU graduate. Research interests include space medicine and telemedicine.

        Robert Richards of Toronto, Canada: Space entrepreneur and futurist. Cofounder of ISU, Singularity University, SEDS. Co-Founder and CEO of Moon Express.

        Trond Krovel of Konstanz Area, Germany: AOCS and GNC Engineer at EADS Astrium. ISU Graduate. Former President of SSETI.

        Jinliang Hou of Shanghai, China: Shanghai Astronomical Observatory CAS, Vice Director Research Center for Galaxies and Cosmology.

        Peter Martinez of Cape Town, South Africa: Division Head for Space Science & Technology at the South African Astronomical Observatory. Current Chair of South African Council for Space Affairs.

        Bill Carswell of Huntsville, Alabama: PhD in Space Materials Processing. Project Management Specialist.

        Chatief Kunjaya of Bandung, Indonesia: Professor of Astronomy at Institute of Technology Bandung.

        Boonrucksar Soonthornthum of Chiang Mai, Thailand, Director of the National Astronomical Research Institute of Thailand

        Diego Mardones of Santiago, Chile: Professor of Astronomy at University of Santiago Chile

        Commander John Young (honorary): Retired NASA Astronaut. Longest career of any USA Astronaut, making 7 space flights over course of 42 years of service. Piloted Gemini, Apollo Command/Service Module, Apollo Lunar Module, Lunar Roving Vehicle & Space Shuttle. 3 Moonwalks during Apollo 16.

        • Nice try but no cigar. The International Lunar Observatory Association is involved with deploying fairly modest lunar observatories including a 2-meter class radio observatory and a 7-cm optical observatory for as part of the Lunar X-Prize competition. They are also involved with the Chinese LUT UV telescope currently operating on the Chang’e 3 lunar lander. From what I can see from the material on the web site, they seem to want to deploy telescopes on the lunar surface to operate at wavelengths that do not penetrate the Earth’s atmosphere. They are not proposing mining lunar materials to build large telescopes at the Lagrange points as you propose (and certainly not for the reasons you state which, like I state, are outdated) nor does any of the information they present contradict anything I have stated above in my reply to your original comment concerning the current state of ground-based telescope technology.

          If you want an up to date tutorial on the current state of large optical telescope technology, I can recommend “The Design and Construction of Large Optical Telescopes” (part of the Springer Astronomy and Astrophysics Library series) by Pierre Bely. As for AO technology, I can recommend “Adaptive Optics for Astronomical Telescopes ” (part of the Oxford Series in Optical & Imaging Sciences) by John Hardy (its a bit dated but still a good text on the topic). Just for the record, I have a degree in physics with a minor in optics. I have 40 years of experience with astronomical observing (amateur and professional), have written about astronomical instrumentation and techniques for 25 years, and have experience with building and designing optical and X-ray telescopes (including several years of R&D work in the 1990s working on synthetic aperture telescopes employing various AO concepts). I hardly consider myself an expert in this field but I have enough of a professional background and working knowledge of the subject to state categorically that you are barking up the wrong tree on this particular topic.

          • Gary Church

            “Nice try but no cigar.”

            I was not after a cigar but it is clear what you are after with another nagging critique.

            “Just for the record, I have a degree in physics with a minor in optics.”

            “I hardly consider myself an expert in this field but I have enough of a professional background and working knowledge of the subject to state categorically that you are barking up the wrong tree on this particular topic.”

            Just for the record the organization is about telescopes on the Moon and so was my comment. You just cannot seem to be able to stand anyone saying anything without tearing it apart and naysaying whatever you can get away with. It does not matter to anyone how many credentials someone boasts about if they are an obnoxious naysayer and insufferable nag.

            • Gary Church

              “-it would be easier and cheaper to build such space telescopes on Earth and launch them into space.”

              About as true as everything else you technobabbled.

              • Gary Church

                Really large mirrors cannot be lifted from the surface of the Earth- they would have to be fabricated on the Moon where there would be no aerodynamic diameter limitations at all in launching them.

                • There is no need to lift really large mirrors from the surface of the Earth to produce large space telescopes. Smaller mirror segments can be fabricated on Earth and combined to produce a larger aperture image. This is the preferred technique today for building large aperture ground based telescopes and it is the technique being employed by NASA for JWST because smaller mirror segments are much easier to fabricate, test and transport than large monolithic optical elements.

                  • Gary Church

                    That “there is no need” is your opinion; a more complicated and not as effective substitute is available but does not make monolithic mirrors undesirable. This kind of subtle argument for accepting second best is used by many pretending they have no agenda. I maintain the obvious agenda here is self-gratification at the expense of other people commenting.

                    • Using arrays of smaller segmented mirrors is not a “second best” solution especially for telescopes with apertures larger than ~8 meters. It is the preferred solution for building large aperture telescopes because smaller mirrors are easier to fabricate, test, assemble and replace, if needed, than large monolithic optics. This is why most of the large aperture telescopes built in recent years and proposed to be built use this technique. If you do not believe me, read a modern text on the design of large optical telescopes like I can recommend “The Design and Construction of Large Optical Telescopes” (part of the Springer Astronomy and Astrophysics Library series) by Pierre Bely which I recommended earlier.

                      As far as agendas, yours is obvious – shove your beliefs down others throats and complain bitterly when the basis of those beliefs are shown to be factually or logically flawed. Please feel free to take it up with the moderators if you have a problem with that.

                    • Gary Church

                      Bitter complaints at your toxic and demeaning replies to my comments need to be shoved down your throat. Sometimes pain is the best teacher.

                    • “Sometimes pain is the best teacher.”

                      It doesn’t seem to stop you from repeating your claims even after they have been disproved.

              • If a factual discussion by someone who is knowledgeable in a field appears to be “technobabble”, that is a sure sign that you do not understand the subject as well as you pretend to.

                • Gary Church

                  “I would like to see an article describing a space telescope at a libration point made to a scale practical with present technology. A system much larger than the present Webb telescope being built. The SLS might be able to lift a disk-shaped fairing containing a mirror considerably larger than the stage diameter.”

                  Your original reply was designed to discredit everything I wrote by discrediting one sentence. It would seem you are not going to let this go and this is going to drag out with ever greater and more arcane sophistry and technobabble on your part. Enjoy.

            • “Just for the record the organization is about telescopes on the Moon and so was my comment.”

              Incorrect. While IOLA is definitely about lunar-based telescopes you stated “I would like to see an article describing a space telescope at a libration point made to a scale practical with present technology.” Further, you stated “Really large mirrors cannot be lifted from the surface of the Earth- they would have to be fabricated on the Moon where there would be no aerodynamic diameter limitations at all in launching them.”

              Your statement had nothing to do with observatories on the Moon. It was about fabricating mirrors on the Moon for deployment elsewhere… which is not what IOLA is proposing. As I stated before, there is nothing on the web site you cite that demonstrates that anything I said in response to your comment is incorrect.

              • Gary Church

                On the Moon or lifted into space from the Moon. It was a comment meant to connect with another subject I wished to express my view on- something you cannot seem to stand either since your favorite criticism concerns going “off-topic.” When someone tries to make every exchange in a discussion into a vehicle to display their prowess at showing how little everyone else knows, it is quite clear what is going on.

                Oh, I understand. You go ahead and argue the tiniest detail. Enjoy.

                • Gary Church

                  Andrew, anyone can see I made a comment and you took it as another opportunity to show everyone that nobody knows anything about anything except you. If I had not commented probably nobody would have. I have purposely left two recent articles alone as examples of this. They are subjects anyone following this discussion board know I have much to say about.

                  I express many views that are not very popular right now and also have obvious political inclinations that are less common on these forums- and perhaps that infers I am a whipping boy to some individuals that seem to think this is their exclusive hangout.

                  I have repeatedly stated that from the first few comments I made on this site you have disagreed with everything I write and cannot stop making negative comments. You increasingly brag about your occupation and credentials in an attempt to intimidate and silence me- it’s not working.

                  • “anyone can see I made a comment and you took it as another opportunity to show everyone that nobody knows anything about anything except you.”

                    I am afraid that seems to be your particular specialty. When I do not know something, I keep quiet and listen to those who do know more about the topic in hopes of learning something new. When someone points out that I am incorrect, I admit my error when proven wrong and learn something new in the process.

                    “I express many views that are not very popular right now and also have obvious political inclinations that are less common on these forums”

                    My responses have nothing to do with with the popularity of your views or your political beliefs. It was about exposing the factual errors in your argument.

                    “I have repeatedly stated that from the first few comments I made on this site you have disagreed with everything I write”

                    Since you seem incapable of hyperbole (and I must therefore take your assertion at face value), your statement is provably false – I do not disagree with everything you write and have publicly stated those areas where we do agree. You just either chose to ignore those areas of agreement or discount it because I do not agree with all of what you say. That is your failing, not mine.

                    “You increasingly brag about your occupation and credentials in an attempt to intimidate and silence me”

                    It is not bragging to establish ones level of expertise in a subject that is under discussion in a forum where the people involved are typically anonymous. In this particular case it was necessary to establish that I have decades of professional experience when it comes to space and ground-based astronomical optical instrumentation and observing techniques and that I am not just an enthusiast with little or no background in the subject who has an interesting idea. I would love to learn more about your areas of technical expertise relating to space technology so that I can better gauge when I am in over my head with discussions with you and would be better served to keep silent and possibly learn something new.

                    • Gary Church

                      “It is not bragging to establish ones level of expertise-”

                      Actually….yes…that is bragging on an anonymous forum. Trying to say you are not is called something else.

                    • You can call it what you wish but I find it useful to know a poster’s area of expertise when it is applicable.

                      For example, there was a discussion about hypergolic propellants and their use in manned spacecraft some time ago. There were lots of opinions flying about but I found that the comments made by a poster who stated he had actually experience working with these propellants as part of the Space Shuttle program carried more weight in lieu of any other sort of proof (e.g. a citation to independent literature on the topic). The fact that one of the moderators (I forget whether it was Mike or Jim) shared a discussion on the issue he had with some engineers that supported what the knowledgeable poster had stated only reinforced his position.

                      The informed opinion of an expert trumps the opinion of a novice. It pays to know the background of a poster when assessing the veracity of contradictory claims on technical issues.

                    • Gary Church

                      “The informed opinion of an expert trumps the opinion of a novice.”

                      It may seem like a game to some where they have to “trump” others- but it is just a way to express my views for me. Those who cred boast and demand technical proofs, peer-reviewed papers, notarized credentials and sworn statements, etc. and typically brand others as “novices” and “experts” don’t seem to understand this is not about winning a prize. Good luck with that.

                    • “It may seem like a game to some where they have to “trump” others”

                      You may view this as some sort of game about whose word to trust or not, but it is not to the rest of us. If I have a medical question, I trust the opinion of a physician over that of random coworker. If I have a question about plumbing, I trust the opinion of a licensed plumber over that of a random neighbor. If I have a question about my car, I trust the opinion of a certified mechanic over a random paserby. When it comes to optics, I trust a professional with proven credentials over some random poster on a web site.

                      If you wish to believe otherwise, good luck with that.

  • Gary the Troll

    Get a life Gary

  • Karol

    Leonidas my friend, I never cease to be amazed by your ability to make a very complex topic not only easy to understand, but fascinating as well! I knew when you “graduated” from posting about the work of others to creating very interesting and informative works of your own that we were in for some exceptionally well-written and researched work. I’m certain that Tom and other members of the AmericaSpace “Old Guard” would join me in saying that you have consistently exceeded our expectations. Great work! As one who has an “old” book in which it is speculated that the thick clouds of Venus may be from a tropical climate which could support lush, verdant forests and that Mars has a series of interesting “canal-like” features, I stand in complete awe of astrophysicists who can determine the weather on these distant alien worlds. I wholly agree with Dr. Ernst de Mooij that, “The detection of light from these planets hundreds to thousands of light years away is on its own remarkable.” To detect a phase cycle variation that is 100,000 times dimmer is, unequivocally . . . astonishing. I wonder why terrestrial weather forecasters never “spiced-up” their usual weather report with, for example, the weather on Venus, “Expect temperatures to reach a high of 900 degrees, so be sure to bring those delicate plants inside. Cloudy today, tomorrow, all week, all month, all year. Sulfuric acid rain continuing throughout the day.” With the House approving the “Ocean Worlds Exploration Program” for the 2016 NASA budget, and our Space Launch System to complete the Critical Design Review in July, I know that you will delight in the future wealth of newly discovered information with which to create even more of your insightful, informative, interesting works. Thank you Leonidas!

  • Another gem, Leonidas! The astounding discoveries yet to come with ever-developing technologies promise an exciting future in “exoplanet exploration.” I was struck by the precise details you talk about, addressing my own “lay perspectives” I bring to each article. Well done!