Seven Earth-like exoplanets discovered orbiting a single nearby star

Astronomers at the University of Liège in Belgium have discovered seven Earth-like exoplanets orbiting a single, nearby star called TRAPPIST-1. The scientists have uncovered these planets with NASA’s Spitzer Space Telescope and several ground-based telescopes, by detecting small decreases in the light intensity of the star as the planets passed in front of it. TRAPPIST-1 is located approximately 40 lightyears from the Earth in the constellation Aquarius and is so small and cool that all seven planets feature temperate conditions, suggesting that liquid water could be present at any of their surfaces. Moreover, three of these planets are located within the habitable zone, the area around a star where conditions are most favorable for life. This discovery, which has been published in Nature, represents a new record for the greatest number of habitable-zone planets found in a single star system and is therefore an important milestone in the search for extraterrestrial life.

For more on the story behind this fascinating discovery, watch the video by NASA below.

Journal reference: Gillon, M. et al. (2017). Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1. Nature, 542(7642), 456–460.

Image: Artist’s impression of the surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 star system. Credit: NASA/JPL-Caltech.

Meteorite reveals two billion year history of volcanism on Mars

Scientists from the University of Houston have discovered that volcanism on Mars occurred over a period of at least two billion years, much longer than previously thought. Their findings are based on geochemical analyses of a Martian meteorite found in northwest Africa and have been published in Science Advances. The meteorite, a type of igneous rock known as shergottite, was found to have an age of approximately 2.4 billion years and is similar in composition and origin to a group of ten other Martian meteorites with ages of 327 to 574 million years. These rocks were likely ejected into space towards the Earth during a single impact 1.1 million years ago, which further suggests that they were all derived from the same volcanic source. Therefore, the spatial and temporal relationships of these meteorites indicate that volcanism must have occurred for over two billion years at the same location. This amazing discovery sheds new light on the formation of the planet and suggests that Mars was to some of the longest-lived volcanoes in the Solar System.

Journal reference: Lapen, T. J., Righter, M., Andreasen, R., Irving, A. J., Satkoski, A. M., Beard, B. L., Nishiizumi, K., Jull, A. J. T. & Caffee, M. W. (2017). Two billion years of magmatism recorded from a single Mars meteorite ejection site. Science Advances, 3(2).

Image: Olympus Mons, the largest volcano on Mars, as seen from the Viking 1 Orbiter. Credit: NASA.

Observation of gravitational waves proves Einstein’s general theory of relativity

An international group of more than a thousand physicists and astronomers has proven the existence of gravitational waves, a 100 years after Albert Einstein’s initial predictions that dramatic outbursts of energy could generate ripples in spacetime at the speed of light. On September 14, 2015, a transient gravitational wave signal was simultaneously observed by the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States. The recorded signal was studied extensively and is thought to have resulted from the collision and merger of two black holes into a single, massive black hole, approximately 1.5 billion years ago. This gravitational wave signal demonstrates the existence of binary black hole systems and is not only the first direct observation of a binary black hole merger, but, more importantly, it represents the most convincing evidence for Albert Einstein’s general theory of relativity to date. Because gravitational waves contain information about their origins and the nature of gravity itself, their discovery holds great promise for improving our understanding of the universe.

Click here to see the fascinating story behind the discovery of gravitational waves.

Journal reference: Abbott, B. P. et al. (LIGO Scientific Collaboration and Virgo Collaboration) (2016). Observation of Gravitational Waves from a Binary Black Hole Merger. Physical Review Letters, 116(6).

Image: Black hole at the center of the Centaurus A galaxy, 13 million lightyears away from Earth. Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray).

Zooplankton migrate under influence of moonlight in dark Arctic winter

New research performed by biologists from different universities has shown that zooplankton migrate vertically through the waters of the Arctic Ocean by using moonlight during dark winter nights. By studying acoustic data recorded by moored instruments, the scientists found that the vertical migration patterns of zooplankton in winter are driven by lunar illumination across the entire Arctic, in fjord, shelf, slope and open sea environments. During the Arctic winter, zooplankton shift their known diel vertical migration (DVM) periods from a solar day (24 hours) to a lunar day (24.8 hours) when the moon rises above the horizon. In addition, mass sinking of zooplankton from the surface waters to a depth of approximately 50 meters occurs during periods of full moon (every 29.5 days). The scientists suggest that lunar vertical migration (LVM) may enable zooplankton to avoid visual predators, such as carnivorous zooplankters, fish and birds, which use moonlight to hunt during the polar night. The discovery of LVM in the Arctic indicates that light-mediated patterns of biological migration may occur even without the presence of sunlight and has important implications for the exchange of carbon between the surface waters and deeper waters during the Arctic winter.

Journal reference: Last, K. S., Hobbs, L., Berge, J., Brierley, A. S. & Cottier, F. (2016). Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter. Current Biology, 26, 1-8.

Image: Icebergs in the Arctic near Cape York, Greenland. Credit: Brocken Inaglory, Wikimedia Commons.

Hydrated salts are evidence for flowing water on Mars

Scientists at NASA have discovered evidence for flowing water on the surface of Mars. Spectral data recorded by the imaging spectrometer of the Mars Reconnaissance Orbiter indicates the presence of hydrated salts in recurring slope lineae at four different locations on the planet. These narrow streaks of low reflectance on the surface of Mars grow in the downslope direction during warm seasons when temperatures reach 250 K – 300 K and fade away during cold seasons. The hydrated salts most likely represent a mixture of magnesium perchlorate (Mg(ClO4)2.H2O), magnesium chlorate (Mg(ClO3)2.H2O) and sodium perchlorate (NaClO4.H2O), and appear to be most abundant when the recurring slope lineae are most extensive. This suggests that these structures are formed as a result of water flowing at the surface or in the shallow subsurface of Mars. The discovery of liquid water is a major step in the search for extant life on Mars.

Journal reference: Ojha, L., Wilhelm, M. B., Murchie, S. L., McEwen, A. S., Wray, J. J., Hanley, J., … & Chojnacki, M. (2015). Spectral evidence for hydrated salts in recurring slope lineae on Mars. Nature Geoscience.

Image: Recurring slope lineae in the Garni Crater on Mars as seen from the Mars Reconnaissance Orbiter. Source: NASA/Jet Propulsion Laboratory-Caltech/University of Arizona.

Fossil remains of new hominin species Homo naledi discovered in South Africa

Paleontologists have discovered the fossil remains of a new hominin species in a dark cave system in South Africa and published their preliminary results in eLife. The new species has been named Homo naledi, which means “star man” in Sotho, after the Dinaledi Chamber of the Rising Star cave system where it was found. Homo naledi is characterized by a small body and brain size, but it also features several adaptations of the hands and feet that are relatively similar to modern humans. The age of Homo naledi and its position in the phylogenetic tree of hominins is still unresolved, but it is believed to be one of the more primitive ancestors of mankind. So far, an unprecedented 1550 remains of at least 15 individuals of Homo naledi have been unearthed, representing the largest fossil assemblage of a single hominin species ever found in Africa. Given the richness and exceptional preservation state of these fossils, it is speculated that Homo naledi may have been capable of performing primitive burial rites.

Journal references:

Berger, L. R., Hawks, J., de Ruiter, D. J., Churchill, S. E., Schmid, P., Delezene, L. K., … & Zipfel, B. (2015). Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife4, e09560.

Dirks, P. H., Berger, L. R., Roberts, E. M., Kramers, J. D., Hawks, J., Randolph-Quinney, P. S., … & Tucker, S. (2015). Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa. eLife4, e09561.

Image: Fossil remains of Homo naledi, the new hominin species discovered in South Africa. Source: Lee Berger, Wikimedia Commons.

Fossil pigments reveal that dinosaurs may have laid colored eggs

Scientists at the University of Bonn have found pigments in fossilized eggs of dinosaurs, which indicates that dinosaurs may have laid colored eggs similar to modern birds. The scientists performed organic geochemical analyses on well preserved, 66 million year old fossil remains of eggshells belonging to the oviraptor Heyuannia huangi and discovered the presence of the pigments protoporphyrin and biliverdin. These pigments are known to be responsible for the blue and green colors in present-day robin and emu eggs, respectively, which suggests that the studied oviraptor eggs may have had blue-green colors as well. It is believed that these oviraptor eggs were laid in partially open ground nests and therefore, their blue-green coloring may have provided a means of camouflage against predators. This study is the first to reconstruct the color of dinosaur eggs and provides a link between the reproductive biology of dinosaurs and the evolutionary traits inherited by modern birds.

Journal reference: Wiemann, J., Yang, T. R., Sander, P. N., Schneider, M., Engeser, M., Kath-Schorr, S., … & Sander, P. M. (2015). The blue-green eggs of dinosaurs: How fossil metabolites provide insights into the evolution of bird reproduction (No. e1323). PeerJ PrePrints.

Image: Reconstruction of Tyrannosaurus rex in Palais de la Découverte, Paris, France. Source: David Monniaux, Wikimedia Commons.

Permian-Triassic mass extinction was caused by ocean acidification

New findings of scientists from several universities published in Science show that the Permian-Triassic mass extinction (~ 252 million years ago), the greatest extinction event of all time, was caused by ocean acidification. The researchers studied boron isotopes from marine sediments in order to reconstruct seawater pH and subsequently combined these data with quantitative modeling techniques to develop a scenario for the mass extinction. Their results show that seawater pH remained relatively stable during the first phase of the extinction, but rapidly shifted to more acidic values during the second phase, which lasted ~ 10 thousand years. This acidification of the oceans had dramatic consequences for life on Earth and is thought to be associated with the release of massive amounts of carbon, related to the volcanism of the Siberian Traps. Up to 96 % of living marine species became extinct during the Permian-Triassic mass extinction and now, it has been shown for the first time that ocean acidification was the responsible mechanism.

Journal reference: Clarkson, M. O., Kasemann, S. A., Wood, R. A., Lenton, T. M., Daines, S. J., Richoz, S., … & Tipper, E. T. (2015). Ocean acidification and the Permo-Triassic mass extinction. Science348(6231), 229-232.

Image: Eruption of the Tavurvur volcano on February 13, 2009 near Rabaul, New Britain, Papua New Guinea. Source: Taro Taylor, Wikimedia Commons.

Emperor penguins on Antarctica forced into refugia during last glacial maximum

Research of biologists published in Global Change Biology indicates that emperor penguins on Antarctica were forced into refugia by extreme cold during the last glacial maximum (~ 19.5 – 16 thousand years ago). By comparing the DNA of fossil emperor penguins with the DNA of living individuals and colonies, the scientists were able to reconstruct the population dynamics of emperor penguins on Antarctica through time. Their results show three mitochondrial clades within emperor penguins at the time of the last glacial maximum, which suggests that these birds were isolated in three small, separate populations and may have survived in refugia such as the Ross Sea. The population sizes of emperor penguins are related to the balance between sea ice available for breeding and open water available for foraging. Sea ice extent around Antarctica was much greater during the last glacial maximum than at present and therefore, reduced food availability resulted in severe losses among populations of emperor penguins.

Journal reference: Younger, J. L., Clucas, G. V., Kooyman, G., Wienecke, B., Rogers, A. D., Trathan, P. N., … & Miller, K. J. (2015). Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum. Global change biology21(6), 2215-2226.

Image: Emperor penguin colony foraging along the Weddell Sea, Antarctica. Source: Christopher Michel, Wikimedia Commons.

Rise of animals on Earth delayed by insufficient oxygen

Geologists of different universities have found that insufficient levels of atmospheric oxygen during the mid-Proterozoic (~ 1.8 billion to 800 million years ago) delayed the evolutionary rise of animals on Earth. They studied chromium isotope data from shallow marine Proterozoic sediments and compared them to younger Phanerozoic sediments deposited in similar environments. Their findings suggest that chromium oxidation in the Proterozoic was very limited and that oxygen levels were at most 0.1 % of present atmospheric levels. Previous estimates of atmospheric concentrations have varied greatly, but it was generally accepted that oxygen existed at Earth’s surface during the Proterozoic. The late appearance and diversification of metazoans was therefore long thought to be limited by genetic advancements and ecological innovation, but now it appears that their evolution was instead delayed by low levels of oxygen.

Journal reference: Planavsky, N. J., Reinhard, C. T., Wang, X., Thomson, D., McGoldrick, P., Rainbird, R. H., … & Lyons, T. W. (2014). Low Mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals. Science346(6209), 635-638.

Image: Cirrus clouds above Warsaw, Poland. Source: Przemyslaw Idzkiewicz, Wikimedia Commons.

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