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).

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.

Milky Way is part of galactic supercluster Laniakea

New findings of astronomers at the University of Hawaii presented in Nature show that the Milky Way is part of a gigantic supercluster of galaxies called Laniakea, which means ‘immeasurable heaven’ in Hawaiian. The scientists used a number of telescopes to measure the distances of galaxies to Earth and calculate their peculiar velocities, in order to create a map of the distribution of matter in space. This newly established cosmic map shows the gravitational flows of galaxies, which congregate in clusters and along filaments that are all interconnected in massive superclusters. The existence of these structures has been known for a long time, but their relationships and especially their boundaries were not well defined. Now, the edges of superclusters have been redrawn along the surface where the flows of galaxies start to diverge, similar to water dividing at a watershed. The resulting Laniakea supercluster we call home has a diameter of 500 million lightyears and contains a grand total of 100.000 galaxies with a combined mass of a hundred million billion Suns.

Click here to view the supplementary video, which beautifully illustrates the structure of Laniakea and the flows of its galaxies.

Journal reference: Tully, R. B., Courtois, H., Hoffman, Y., & Pomarède, D. (2014). The Laniakea supercluster of galaxies. Nature513(7516), 71-73.

Image: The Milky Way as seen from the Karakoram Range, Pakistan. Source: Anne Dirkse, Wikimedia Commons.