Tellurium Detected for the First Time in Ancient Stars

Nearly 13.7 billions years ago our universe consisted of three basic elements which included hydrogen, helium, and a little bit of lithium. However, 300 million years ago when the stars first began to emerge, new elements were formed. Now there are around 100 different elements in our universe, including the rare element Tellurium.

Tellurium has been rarely found on Earth, which is why hardly anyone has ever heard of it. It is a superconductive element that was found in ancient stars near the outskirts of the Milky Way galaxy. Common elements such as Iron and Nickle can be created by any ordinary supernova, but Tellurium is in a group of heavy elements that can only be created through specialized supernovas.

During rapid nuclear fusion, heavy elements are formed creating elements such as Tellurium. It is called the r-process, which occurs when atomic nuclei become bombarded by neutrons during a supernova explosion. The result is the creation of heavier elements that are not as common as some of the lighter elements that are much more abundant. This Tellurium discovery was an interesting find for astronomers, and is yet another step towards unraveling the mystery of these special supernovas.

Image Credit:


Ian U. Roederer, James E. Lawler, John J. Cowan, Timothy C. Beers, Anna Frebel, Inese I. Ivans, Hendrik Schatz, Jennifer S. Sobeck, & Christopher Sneden (2012). Detection of the Second r-process Peak Element Tellurium in Metal-Poor Stars The Astrophysical Journal Letters, 747 (1) DOI: arXiv:1202.2378

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Let’s Explore Solar System Seismic Activity

Volcanoes: Io (which is slightly larger than the Earth

The U.S. Geological survey estimates that Earth experiences several million earthquakes and around 50 volcanic eruptions every year. But ours is not the only cosmic body that experiences seismic activity: ongoing exploration of the Solar System and the Universe by astronomers and other scientists indicates that volcanic eruptions and quakes (some similar to those on Earth and others vastly different) have been observed on our Moon as well as a growing list of planets, exo-moons, and stars within our galaxy.

The term seismic activity refers to the propagation and movement of elastic waves, called seismic waves, through a planetary body due to perturbations deep beneath its surface or in its upper layers. These waves cause quakes — the shaking and rolling motions that shifts a planet’s upper crust and surface. Quakes can have numerous causes; on Earth, movement of the tectonic plates that make up the planet’s surface, and the molten rock in the mantle beneath it, is the primary cause of earthquakes here at home.

On other bodies within the Solar System including our sun, seismic activity can be caused by other processes as well.  Tidal forces, pressures from cold gases and the roiling of the outer layers of a star can create movements which produce seismic waves, some capable of causing quakes and eruptions many times stronger than those observed on Earth.

The planets of our Solar System can be grouped according to their shared features and distance from the Sun.  The inner planets –Mercury, Venus, Earth and Mars — orbit close to the Sun and are composed primarily of rock, with a solid outer crust.  Beyond Mars, the “gas giants” Jupiter, Saturn, Uranus and Neptune consist largely of hydrogen, ammonia and methane gases around a small, solid core.

Because the inner planets, Earth’s closest neighbors in space, share a hard crust and an originally molten core, all show evidence of volcanic activity. Even tiny Mercury, closest to the Sun, reveals features characteristic of past eruptions.  Photographs and probes of Venus, with its hot cloudy atmosphere, and dry cold Mars also show fault lines, volcanic mountains and ancient lava flows indicating a seismically active past, when planetary cores were hotter and more liquid.

Composed largely of gasses, the outer planets lack a surface crust and a volatile molten core — key features necessary for large-scale planetary seismic activity.  However, in January 2011, advances in asteroseismology (the study of seismic activity on stars) delivered a surprise:  seismic waves were detected on Jupiter, whose composition – liquids and gases around a small rocky core – actually resembles that of the sun.

A variety of factors cause quakes on our moon and others in the Solar System, where evidence of past and present seismic activity has been captured in photographs.  Quakes on our own solitary Moon are caused not by movement of tectonic plates or lava, but by the pull of Earth’s gravity and the expansion of the moon’s cold crust when sunlight returns to its surface after the long lunar night, which lasts 14 Earth days.

Jupiter’s large moon Io experiences extensive seismic activity due to internal friction caused by Jupiter’s gravitational pull. Images of Io, Neptune’s moon Triton and Enceladus, a large moon of Saturn, also reveal evidence of massive cryovolcanic eruptions – explosions caused by pressures of cold or frozen gases beneath the moon’s surface.

Since stars consist primarily of gases, seismic waves observed on stars are believed to originate from turbulence in the outer, convective zone rather than the core. Some of these “star quakes” generate enough energy to cause the entire star to vibrate like a bell. Although our Sun is of course a star, helioseismology (from Greek, Helios: sun), a subspecialty of asteroseismology, focuses on the seismic activity detected there. A solar flare can generate sunquakes, some of which produce energy equivalent to earthquakes of magnitude 11 or stronger.

Beyond the orbit of Neptune, the Kuiper Belt is a region of small icy objects thought to be remnants from the formation of the Solar System. Although Kuiper Belt objects are composed largely of ices such as methane and ammonia, some hints of seismic activity can be observed even there. At 783 miles (1260 km) wide — large enough to have its own name — the Kuiper Belt Object Quaour has an observable surface area containing features suggestive of cryovolcanic changes.

Although conditions on our Earth are ripe for frequent quakes and eruptions, ongoing exploration and observation of the Solar System and the universe beyond reveal that, at least as far as seismic activity is concerned, we truly are not alone in the cosmos.

Image Credit: SOHO/NASA


Martínez-Oliveros, J., Moradi, H., Besliu-Ionescu, D., Donea, A., Cally, P., & Lindsey, C. (2007). From Gigahertz to Millihertz: A Multiwavelength Study of the Acoustically Active 14 August 2004 M7.4 Solar Flare Solar Physics, 245 (1), 121-139 DOI: 10.1007/s11207-007-9004-8

A. Grigahcène, M.-A. Dupret, S. G. Sousa, M. J. P. F. G. Monteiro, R. Garrido, R. Scuflaire, & M. Gabriel (2011). Towards precise asteroseismology of solar-like stars Astrophysics and Space Science Proceedings series (ASSP) DOI: arXiv:1112.5961
Sibani, P., & Christiansen, S. (2008). Thermal shifts and intermittent linear response of aging systems Physical Review E, 77 (4) DOI: 10.1103/PhysRevE.77.041106

Sibani, P., & Christiansen, S. (2008). Thermal shifts and intermittent linear response of aging systems Physical Review E, 77 (4) DOI: 10.1103/PhysRevE.77.041106

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Chandra Discovers the Fastest Wind From a Stellar-Mass Black Hole

Making use of NASA’s Chandra X-ray Observatory, astronomers recently announced that they have recorded the quickest wind ever recorded coming off of a stellar-mass black hole. This discovery has important implications for how exactly these type of black holes work.

This record-breaking wind was found to be moving at about 20 million mph, which is about three percent of the speed of light. This is about ten times as fast as astronomers have ever witnessed coming off of a stellar-mass black hole.

Stellar-mass black holes, such as this one, become formed when large stars reach their end and collapse. They have an approximate mass of five to ten times that of our sun. The stellar-mass black hole that produced these particular winds was IGR J17091-3624. These winds are the equivalent of a cosmic category five hurricane, which took astronomers by surprise to see such powerful winds coming from a stellar-mass black hole such as this one. This black hole is relatively small compared to some of the other black holes astronomers have discovered, yet it has produced winds that far exceed that of the larger black holes.

Unlike winds found on Earth, the winds found in the black hole blow in various directions rather then in a single direction. This would send you on quite a ride!

Image Credit: NASA/CXC/M.Weiss

Reference: finds fastest wind from stellar-mass black hole.aspx

Changing Faces of Titan

A set of recent papers, many of which draw on data from NASA’s Cassini spacecraft, reveal new details in the emerging picture of how Saturn’s moon Titan shifts with the seasons and even throughout the day. The papers, published in the journal Planetary and Space Science in a special issue titled “Titan through Time”, show how this largest moon of Saturn is a cousin – though a very peculiar cousin – of Earth.

“As a whole, these papers give us some new pieces in the jigsaw puzzle that is Titan,” said Conor Nixon, a Cassini team scientist at the NASA Goddard Space Flight Center, Greenbelt, Md., who co-edited the special issue with Ralph Lorenz, a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. “They show us in detail how Titan’s atmosphere and surface behave like Earth’s – with clouds, rainfall, river valleys and lakes. They show us that the seasons change, too, on Titan, although in unexpected ways.”

This series of false-color images obtained by NASA

A paper led by Stephane Le Mouelic, a Cassini team associate at the French National Center for Scientific Research (CNRS) at the University of Nantes, highlights the kind of seasonal changes that occur at Titan with a set of the best looks yet at the vast north polar cloud.

A newly published selection of images – made from data collected by Cassini’s visual and infrared mapping spectrometer over five years – shows how the cloud thinned out and retreated as winter turned to spring in the northern hemisphere.

Cassini first detected the cloud, which scientists think is composed of ethane, shortly after its arrival in the Saturn system in 2004. The first really good opportunity for the spectrometer to observe the half-lit north pole occurred on December 2006. At that time, the cloud appeared to cover the north pole completely down to about 55 degrees north latitude.  But in the 2009 images, the cloud cover had so many gaps it unveiled to Cassini’s view the hydrocarbon sea known as Kraken Mare and surrounding lakes.

“Snapshot by snapshot, these images give Cassini scientists concrete evidence that Titan’s atmosphere changes with the seasons,” said Le Mouelic. “We can’t wait to see more of the surface, in particular in the northern land of lakes and seas.”

In data gathered by Cassini’s composite infrared mapping spectrometer to analyze temperatures on Titan’s surface, not only did scientists see seasonal change on Titan, but they also saw day-to-night surface temperature changes for the first time. The paper, led by Valeria Cottini, a Cassini associate based at Goddard, used data collected at a wavelength that penetrated through Titan’s thick haze to see the moon’s surface. Like Earth, the surface temperature of Titan, which is usually in the chilly mid-90 kelvins (around minus 288 degrees Fahrenheit), was significantly warmer in the late afternoon than around dawn.

“While the temperature difference – 1.5 kelvins – is smaller than what we’re used to on Earth, the finding still shows that Titan’s surface behaves in ways familiar to us earthlings,” Cottini said. “We now see how the long Titan day (about 16 Earth days) reveals itself through the clouds.”

A third paper by Dominic Fortes, an outside researcher based at University College London, England, addresses the long-standing mystery of the structure of Titan’s interior and its relationship to the strikingly Earth-like range of geologic features seen on the surface. Fortes constructed an array of models of Titan’s interior and compared these with newly acquired data from Cassini’s radio science experiment.

The work shows the moon’s interior is partly or possibly even fully differentiated. This means that the core is denser than outer parts of the moon, although less dense than expected. This may be because the core still contains a large amount of ice or because the rocks have reacted with water to form low-density minerals.

Earth and other terrestrial planets are fully differentiated and have a dense iron core. Fortes’ model, however, rules out a metallic core inside Titan and agrees with Cassini magnetometer data that suggests a relatively cool and wet rocky interior. The new model also highlights the difficulty in explaining the presence of important gases in Titan’s atmosphere, such as methane and argon-40, since they do not appear to be able to escape from the core.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson. The composite infrared spectrometer team is based at NASA’s Goddard Space Flight Center in Greenbelt, Md., where the instrument was built. The radio science subsystem has been jointly developed by NASA and the Italian Space Agency.

Source: JPL/NASA


Rodriguez S, Le Mouélic S, Rannou P, Tobie G, Baines KH, Barnes JW, Griffith CA, Hirtzig M, Pitman KM, Sotin C, Brown RH, Buratti BJ, Clark RN, & Nicholson PD (2009). Global circulation as the main source of cloud activity on Titan. Nature, 459 (7247), 678-82 PMID: 19494910

Fortes, D. (2008). Uncovering Titan’s secrets Nature Geoscience, 1 (7), 415-416 DOI: 10.1038/ngeo238

Fortes, A., & Grindrod, P. (2006). Modelling of possible mud volcanism on Titan Icarus, 182 (2), 550-558 DOI: 10.1016/j.icarus.2005.11.013

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Let’s Explore the Phases of Matter: Sublimation and Deposition

Image Credit: European Space Agency/David Hardy

The Basic Phases
Science recognizes four states of matter that we can find in every day life. These include solid, liquid, gas and plasma. Other states (I’ve written about a few of them here) such as Bose-Einstein, supercritical fluid, and degenerate gas occur in extreme conditions, but I’m focusing primarily on phases today. It is important to remember that matter remains the same substance regardless of which state it is in. For example, water is still water, regardless of whether it is ice or in a cloud. What makes the difference is the amount of energy in the matter. The more energy the atoms in the matter have, the further apart the atoms become. Thus, solids are denser than liquids, liquids are denser than gases and so on. The energy that excites atoms typically is heat. The phase change puzzle doesn’t include only energy, however. It also includes pressure. The higher the pressure, the harder it is for matter to expand in response to the extra energy present, so phase changes become more difficult as pressure increases.

Although matter usually goes through phase changes gradually as heat energy is added or taken away, in some situations, there is enough energy present that matter can go directly from the solid state to the gaseous state. This is called sublimation. Sublimation occurs most easily when pressure is low because the atoms have less resistance when trying to expand.

Deposition is perhaps the lesser-known cousin of sublimation. It occurs when matter skips from the gaseous state directly to the solid state. This requires energy to be lost quickly. A good example of this is frost. Deposition occurs most easily when pressure is high because the pressure makes it easier for atoms to come closer together to form a solid.

What Does This Have to Do with Astronomy?

Glad you asked!

Comets like the comet Hyakutake are an excellent example of sublimation at work. Comets consist mostly of what I think of as dirty ice and dust. If you live in an area where it snows, you’ve likely seen how snow and ice on roads turns dark as it’s mixed with dirt. Hence, dirty ice. Anyhow, as comets approach the Sun, the radiated heat warms and sublimates the large mass of ice found in the comet. As a result, gas is released in the form of a temporary atmosphere or cloud around the comet known as a coma. Because comets have virtually no gravity, this temporary atmosphere is unsustained by the comet. As a result, the coma is flung away from the comet and results in the streaming tail that you see behind comets as they soar through space. So this is a great example of sublimation occurring in our universe.

Examples of sublimation can also be found on many planets and moons in our solar system as well. Many of these masses have little or extremely low pressure atmospheres resulting in ice buildup on their surfaces. When the ice is heated, sublimation occurs if the pressure is low enough. We see this occurring frequently on Mars during the Martian summer season. The planet has polar ice caps that sublimate into the atmosphere during the Martian summer season at its’ poles.


Heiselberg, H. (2000). Phases of dense matter in neutron stars Physics Reports, 328 (5-6), 237-327 DOI: 10.1016/S0370-1573(99)00110-6

Image Credit: European Space Agency/David Hardy

Building Blocks of Early Earth – Collision that Created Moon

Unexpected new findings by a University of Maryland team of geochemists show that some portions of the Earth’s mantle (the rocky layer between Earth’s metallic core and crust) formed when the planet was much smaller than it is now, and that some of this early-formed mantle survived Earth’s turbulent formation, including a collision with another planet-sized body that many scientists believe led to the creation of the Moon.

“It is believed that Earth grew to its current size by collisions of bodies of increasing size, over what may have been as much as tens of millions of years, yet our results suggest that some portions of the Earth formed within 10 to 20 million years of the creation of the Solar System and that parts of the planet created during this early stage of construction remained distinct within the mantle until at least 2.8 billion years ago.” says UMD Professor of Geology Richard Walker, who led the research team.

Prior to this finding, scientific consensus held that the internal heat of the early Earth, in part generated by a massive impact between the proto-Earth and a planetoid approximately half its size (i.e., the size of Mars), would have led to vigorous mixing and perhaps even complete melting of the Earth. This, in turn, would have homogenized the early mantle, making it unlikely that any vestiges of the earliest-period of Earth history could be preserved and identified in volcanic rocks that erupted onto the surface more than one and a half billion years after Earth formed.

However, the Maryland team examined volcanic rocks that flourished in the first half of Earth’s history, called komatiites, and found that these have a different type of composition than what they, or anyone, would have, expected. Their findings were just published in the journalScience: “182W Evidence for Long-Term Preservation of Early Mantle Differentiation Products,” by Mathieu TouboulIgor S. Puchtel, and Richard J. Walker, University of Maryland. Their laboratory and work are supported by funding from the National Science Foundation and NASA.

An Isotopic Signature

“We have discovered 2.8 billion year old volcanic rocks from Russia that have a combination of isotopes of the chemical element tungsten that is different from the combination seen in most rocks — different even from the tungsten filaments in incandescent light bulbs,” says the first author, Touboul, a research associate in the University of Maryland’s Department of Geology. “We believe we have detected the isotopic signature of one of the earliest-formed portions of the Earth, a building block that may have been created when the Earth was half of its current mass.”

As with many other chemical elements, tungsten consists of different isotopes. All isotopes of an element are characterized by having the same number of electrons and protons but different numbers of neutrons. Therefore, isotopes of an element are characterized by identical chemical properties, but different mass and nuclear properties. Through radioactive decay, some unstable (radioactive) isotopes spontaneously transform from one element into another at a specific, but constant, rate. As a result, scientists can use certain radioactive isotopes to determine the age of certain processes that happen within the Earth, as well as for dating rocks.

For the Maryland team the tungsten isotope182-tungsten (one of the five isotopes of tungsten) is of special interest because it can be produced by the radioactive decay of an unstable isotope of the element hafnium, 182-hafnium.

According to the UMD team, the radioactive isotope 182-hafnium was present at the time our Solar System formed, but is no longer present on Earth today. Indeed, decay of 182-hafnium into 182-tungsten is so rapid (~9 million year half-life) that variations in the abundance of 182-tungsten relative to other isotopes of tungsten can only be due to processes that occurred very early in the history of our Solar System, they say.

The Maryland geochemists found that the 2.8 billion year old Russian komatiites from Kostomuksha have more of the tungsten isotope 182-W than normal. “This difference in isotopic composition requires that the early Earth formed and separated into its current metallic core, silicate mantle, and perhaps crust, well within the first 60 million years after the beginning of our 4.57-billion-year-old Solar System,” says Touboul.

“In itself this is not new,” he says, “but what is new and surprising is that a portion of the growing Earth developed the unusual chemical characteristics that could lead to the enrichment in 182-tungsten; that this portion survived the cataclysmic impact that created our moon; and that it remained distinct from the rest of the mantle until internal heat melted the mantle and transported some of this material to the surface 2.8 billion years ago, allowing us to sample it today.”

Higher Precision Yields New Findings, Insights

The UMD team explained that they were able to conduct this research because they have developed new techniques that allow the isotopic composition of tungsten to be measured with unprecedented precision. “We do this by chemically separating and purifying the tungsten from the rocks we study. We then use an instrument termed a mass spectrometer to measure the isotopic composition of the tungsten”

According to the researchers their new findings have far reaching implications for understanding how Earth formed; how it differentiated into a metallic core, rocky mantle and crust; and the dynamics of change within the mantle.

“These findings indicate that the Earth’s mantle has never been completely melted and homogenized, and that convective mixing of the mantle, even while Earth was growing, was evidently very sluggish,” says Walker. “Many questions remain. The rocks we studied are 2.8 billion years old. We don’t know whether the portion of the Earth with this unusual isotopic composition or signature can be found in much younger rocks. We plan to analyze some modern volcanic rocks in the near future to assess this.”

Source: University of Maryland

GJ 1214b: A New Class of Planet Discovered

Many fans of NASA and the European Space Agency have probably paid less attention to the Hubble Space Telescope in recent years, but observations from the platform suggest that a new class of planet is on the horizon. With a steamy atmosphere and a watery surface, GJ 1214b orbits a red dwarf star that is 40 light-years from Earth – a distance that puts the new planet in a position to be studied by the James Webb Space Telescope. As of today, there are no other planets that have similar characteristics to GJ 1214b. This includes planets both in our solar system as well as those in myriad other star systems known to have planetary bodies orbiting them.

It seems to orbit its sun once every 38 hours, and maintains a distance of 2,000,000 kilometers from it. Future travelers probably won’t be taking too many trips to GJ 1214b however, since it has a surface temperature that’s estimated to be around 230°C. Scientists have suggested that the extreme temperature and pressure could form extremely interesting substances, however. Water that’s super fluid might very well be present on the world, and hot ice might even be present.

So far, astronomers have used the Hubble Space Telescope to obtain significant information and measurements pertaining to the new planet. With high temperatures and high pressures, the atmosphere of GJ 1214b is much steamier than the atmosphere of Earth. Apparently, the planet formed when it was further away from the star than it is now. It then slowly migrated towards its sun.

European Space Agency (2012, February 21). Hubble Reveals a New Class of Extrasolar Planet. Retrieved February 21, 2012, from

Journal Reference:

Berta, Z., Charbonneau, D., Désert, J., Miller-Ricci Kempton, E., McCullough, P., Burke, C., Fortney, J., Irwin, J., Nutzman, P., & Homeier, D. (2012). THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE The Astrophysical Journal, 747 (1) DOI: 10.1088/0004-637X/747/1/35

Image: GJ1214b, shown in this artist’s view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from the NASA/ESA Hubble Space Telescope show that it is a waterworld enshrouded by a thick, steamy atmosphere. GJ 1214b represents a new type of planet, like nothing seen in the Solar System or any other planetary system currently known. Credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

Milky Way’s Black Hole Devouring Asteroids?

At the center of the Milky Way galaxy (encompasses our solar system) there is a black hole that features a mass of more than three million times that of the sun at its center. This black hole, known as Sagittarius A (SGR A for short), has been detected through various sources of radiation that stem from the direction of the center of the galaxy. However, SGR A has now been found to be grazing and vaporizing asteroids that pass near it according to recent data released from NASA’s Chandra X-ray Observatory. This discovery comes with the finding that there is a cloud of trillions of asteroids and comets hovering around the black hole. Such a finding redefines the current environmental criteria for an asteroid or comet to form in space.

SGR A has likely been consuming tremendous numbers of asteroids as of late as the black hole has been emanating x-ray radiation in larger quantities than usual. Black holes hold true to the notion that ‘what goes in must come out,’ so they often spit out high amounts of radiation as they consume stellar objects. The asteroids and comets from the nearby cloud that pass within approximately 100 million miles of SGR A are likely hopelessly shredded. The space rocks are destroyed due to the high tidal forces associated with the black hole’s mass which creates enormous friction. The asteroids and comets are ripped apart in a similar fashion by which Saturn forms its rings with the exception that these rocks burn up like a meteor. This discovery is just one more clue to the overall mystery of the Milky Way galaxy.

Image credit:

Let’s Explore Photosynthesis on Exoplanets

Imagine an astronaut stepping out of a spacecraft onto the surface of an extrasolar planet that is capable of sustaining life. Now imagine the astronaut is greeted by the sight of red colored trees and grass. Such a scenario could be more reality than science fiction because of the variances in photosynthesis theorized to exist in other parts of the Milky Way Galaxy.

Photosynthesis occurs in plants when they use sunlight to create foods from carbon dioxide and water. This process of converting energy from sunlight into chemical energy produces oxygen and causes chlorophyll to form. It is chlorophyll that is responsible for imbuing plants with a healthy green color. The reason this happens is because chlorophyll absorbs more blue and red light waves and fewer green light waves from sunlight. Reflecting the green light waves is what causes the plants to appear green to the human eye.

When the Sun in our solar system radiates light, it reaches the Earth in a particular distribution of colors. As this sunlight passes through the Earth’s atmosphere, the various gases that comprise the atmosphere filter out certain colors before they strike the surface of the Earth. Much of the color that is not absorbed in the atmosphere is red, blue or green. Plants tend to absorb a greater amount of red and blue rays and reflect back green.

Some scientists think that plant life growing under the rays of an extraterrestrial sun could reflect colors other than green after the photosynthesis process is completed. The color that is most commonly visible on alien plants correlates with how colors are distributed in the light radiated by the parent star that strikes the surface of the extraterrestrial world.

The spectral type of a main sequence star can have a direct impact on the coloring of plants. For that reason, coloring can vary from star to star if the spectral type for each star also shows some variance. In a scientific paper published in the March, 2007 issue of Astrobiology magazine, a team of scientists examined how light emitted by another sun would appear from the vantage point of a planet orbiting that host star. Nancy Kiang, author of the paper, said the scientific team determined that the atmosphere of any extrasolar Earth-like planet would feature a chemical composition that is compatible with the chemical composition of its host star. How light from that star is seen on the planet’s surface would be affected by how it is filtered through the atmosphere as it reaches the surface.

Kiang, who works with the Goddard Institute for Space Sciences at NASA, and her team conducted an extensive study where they modeled how sunlight would reach the surface of Earth-sized planets that are hospitable to life from stars of varying spectral types. Kiang’s team speculated that each planet could experience different dominant colors that emerge in plants through photosynthesis based on how hot or cool the sun is that is anchoring that solar system.

Plant life existing on other worlds is not guaranteed to mimic the appearance of plants we are accustomed to seeing on Earth. Planets revolving around a blue star could feature plant life that has a dominant color of yellow or orange and this could lend to forests that boast autumn type colors throughout the growing season on those planets. If a habitable world is located in a binary star system or multi-star system, it could cause some exotic variations in how the plant life grows and appears to the human eye after going through photosynthesis. These planets could have plants that are almost black in color.

In the case of habitable planets around red dwarf stars, all plant life would likely exist underwater. The proximity of the habitable zone around the star would make it difficult for plants to fend off ultraviolet radiation because they could not generate enough energy from infrared light through photosynthesis to create sufficient oxygen to block ultraviolet radiation penetrating the atmosphere.

The idea that differences exist in the photosynthesis process from one planet to the next changes how astrobiologists search for evidence of life on other worlds outside our own solar system. It reinforces the idea that plant and animal life alike have evolved and adapted to fit the unique conditions of this Earth as well as reinforcing the notion that life on other habitable planets would evolve to survive and thrive in a similar manner on other planets. What do you think? Is photosynthesis the same on all planets or do you think it will be vastly different?

Kiang, N., Siefert, J., Govindjee, ., & Blankenship, R. (2007). Spectral Signatures of Photosynthesis. I. Review of Earth Organisms Astrobiology, 7 (1), 222-251 DOI: 10.1089/ast.2006.0105

Kiang, N., Segura, A., Tinetti, G., Govindjee, ., Blankenship, R., Cohen, M., Siefert, J., Crisp, D., & Meadows, V. (2007). Spectral Signatures of Photosynthesis. II. Coevolution with Other Stars And The Atmosphere on Extrasolar Worlds Astrobiology, 7 (1), 252-274 DOI: 10.1089/ast.2006.0108

Artist’s Impression of an Exoplanet with Moons, Orbiting the Star HD70642 (Photo Credit: David A. Hardy, © PPARC)

Intelligent Life in the Universe


We cannot completely discount the possibility that alien life will look or act like us, not least of all given the statistical probabilities. The laws of natural selection alone may no longer govern humans; however, whilst cloning and gene manipulation may allow human enhancement and the curing of disease, we are still constrained by the physiological limitations hard-coded into our genes. Other carbon-based life forms might utilize the same chemical structures (DNA or even RNA) as information carriers, especially with these molecules found in abundance throughout the interstellar medium. On the other hand they may be completely different. Extrapolate to the practical applications of, say, superstring physics (if it’s right) and maybe they can put their intelligence into non-biological forms. Arthur C. Clarke said that what they could do would be like magic to us. Read More →