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How we’re already seeking life on TRAPPIST-1’s rocky planets

Astronomy News - 2 March 2017 - 9:14am

The dim star TRAPPIST-1 hosts seven rocky worlds, at least three of which may have liquid water and atmospheres. Here’s how we’re going to find out if anyone lives there

A Galaxy on the Edge

Astronomy News - 2 March 2017 - 9:11am
This colourful stripe of stars, gas, and dust is actually a spiral galaxy named NGC 1055. Captured here by ESO’s Very Large Telescope (VLT), this big galaxy is thought to be up to 15 percent larger in diameter than the Milky Way. NGC 1055 appears to lack the whirling arms characteristic of a spiral, as it is seen edge-on. However, it displays odd twists in its structure that were probably caused by an interaction with a large neighbouring galaxy.

Rapid changes point to origin of ultra-fast black hole winds

Astronomy News - 2 March 2017 - 9:10am

ESA and NASA space telescopes have made the most detailed observation of an ultra-fast wind flowing from the vicinity of a black hole at nearly a quarter of the speed of light.

The greatest danger asteroids pose to us is not from the impact

Astronomy News - 27 February 2017 - 9:12am

If an asteroid hits a major city, only 3 per cent of the casualties will be from the crater it forms – most will be from overheated air and high winds

Cosmic blast from the past [heic1704]

Astronomy News - 27 February 2017 - 9:10am

Three decades ago, a massive stellar explosion sent shockwaves not only through space but also through the astronomical community. SN 1987A was the closest observed supernova to Earth since the invention of the telescope and has become by far the best studied of all time, revolutionising our understanding of the explosive death of massive stars.

Seven Earth-sized planets found orbiting single star

Astronomy News - 27 February 2017 - 9:09am

Seven planets orbiting a single star have been discovered in a solar system 40 light-years from Earth.

Exoplanet discovery: Seven Earth-size exoplanets may have water

Astronomy News - 24 February 2017 - 9:30am

The small, cool star TRAPPIST-1 is one of the best places to look for life in the Milky Way: its seven rocky planets might all have water and atmospheres

Voyager 1 might have seen Enceladus’ icy plumes 25 years early

Astronomy News - 24 February 2017 - 9:29am

A space image-processing enthusiast claims that he’s found signs of Saturn’s moon’s majestic plumes from 1980 – decades before they were discovered

Astronomy: Earth's seven sisters

Astronomy News - 23 February 2017 - 9:24am

Astronomy: Earth's seven sisters

Nature 542, 7642 (2017). doi:10.1038/542421a

Authors: Ignas A. G. Snellen

Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets. See Letter p.456

Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

Astronomy News - 23 February 2017 - 9:23am

Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

Nature 542, 7642 (2017). doi:10.1038/nature21360

Authors: Michaël Gillon, Amaury H. M. J. Triaud, Brice-Olivier Demory, Emmanuël Jehin, Eric Agol, Katherine M. Deck, Susan M. Lederer, Julien de Wit, Artem Burdanov, James G. Ingalls, Emeline Bolmont, Jeremy Leconte, Sean N. Raymond, Franck Selsis, Martin Turbet, Khalid Barkaoui, Adam Burgasser, Matthew R. Burleigh, Sean J. Carey, Aleksander Chaushev, Chris M. Copperwheat, Laetitia Delrez, Catarina S. Fernandes, Daniel L. Holdsworth, Enrico J. Kotze, Valérie Van Grootel, Yaseen Almleaky, Zouhair Benkhaldoun, Pierre Magain & Didier Queloz

One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away. The transiting configuration of these planets, combined with the Jupiter-like size of their host star—named TRAPPIST-1—makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities. Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.

Planetary science: Ceres has complex chemistry

Astronomy News - 23 February 2017 - 9:22am

Planetary science: Ceres has complex chemistry

Nature 542, 7642 (2017). doi:10.1038/542395a

The dwarf planet Ceres hosts organic compounds that are possible ingredients for life.NASA's Dawn spacecraft is orbiting Ceres (pictured), which is also the largest asteroid in the Solar System, and the craft has previously spotted signs of salts, ice and other basic

Pluto could be staging a comeback — and it’s not alone

Astronomy News - 23 February 2017 - 9:22am

Pluto could be staging a comeback — and it’s not alone

Nature 542, 7642 (2017). doi:10.1038/542392b

A proposal to massively expand the number of bodies called planets raises interesting questions.

Newly discovered planets could have water on their surfaces

Astronomy News - 23 February 2017 - 9:14am

The team has been using the TRAPPIST–South telescope at the European Space Observatory’s (ESO) La Silla Observatory, the Very Large Telescope (VLT) at Paranal, the NASA Spitzer Space Telescope as well as two other telescopes supported by the UK’s STFC, the William Herschel Telescope and the Liverpool Telescope. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes comparable to Earth.

The astronomers identified the planets thanks to periodic drops in the brightness of the central star. As the planets passed in front of the star, they cast a shadow, events known as transits, from which the team could measure the planet’s orbital periods and calculate their sizes and masses. They found that the inner six planets were comparable in size, mass and temperature to the Earth raising the possibility that they host liquid water on their surface.

With just 8% the mass of the Sun, TRAPPIST-1 is very small in stellar terms, only marginally bigger than the planet Jupiter — and though nearby in the constellation Aquarius, it is invisible visually with anything less than powerful telescopes. Astronomers expected that such dwarf stars might host many Earth-sized planets in tight orbits, making them promising targets in the hunt for extraterrestrial life. TRAPPIST-1 is the first such system to be discovered.

Co-author Dr Amaury Triaud, of the University of Cambridge’s Institute of Astronomy, explains: “Stars like TRAPPIST-1 belong to the most common type of stars that exist within our Galaxy. The planets that we found are likely representative of the most common sort of planets in the Universe. 

“That the planets are so similar to Earth bodes well for the search for life elsewhere. Planets orbiting ultra-cool dwarfs, like TRAPPIST-1, likely represent the largest habitable real estate in the Milky Way!”

The seven planets of the TRAPPIST-1 system. Credit: ESO

The team determined that all the planets in the system were similar in size to Earth and Venus in our Solar System, or slightly smaller. The density measurements suggest that at least the innermost six are probably rocky in composition.

The planetary orbits are not much longer than that of Jupiter’s Galilean moon system, and much smaller than the orbit of Mercury in the Solar System. However, TRAPPIST-1’s small size and low temperature means that the energy input to its planets is similar to that received by the inner planets in our Solar System; TRAPPIST-1c, d and f receive similar energy inputs to Venus, Earth and Mars, respectively.

All seven planets discovered in the system could potentially have liquid water on their surfaces, though their orbital distances make some of them more likely candidates than others. Climate models suggest the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water, except maybe on a small fraction of their surfaces. The orbital distance of the system’s outermost planet, TRAPPIST-1h, is unconfirmed, though it is likely to be too distant and cold to harbour liquid water — assuming no alternative heating processes are occurring. TRAPPIST-1e, f, and g, however, are of more interest for planet-hunting astronomers, as they orbit in the star’s habitable zone and could host oceans of surface water.

These new discoveries make the TRAPPIST-1 system an even more important target in the search for extra-terrestrial life. Team member Didier Queloz, from the University of Cambridge’s Cavendish Laboratory, is excited about the future possibilities: “Thanks to future facilities like ESO’ Extremely Large Telescope, or NASA/ESA’s soon-to-be-launched James Webb Space telescope, we will be capable to measure the structure of the planets’ atmospheres, as well as their chemical composition. We are about to start the remote exploration of terrestrial climates beyond our Solar system.”

The discovery is described in Nature, which also includes a science fiction short story, written by Laurence Suhner. Amaury Triaud comments: “We were thrilled at the idea of having artists be inspired by our discoveries right away. We hope this helps convey the sense of awe and excitement that we all have within the team about the TRAPPIST-1 system.”

The star draws its name from the TRAPPIST-South telescope, which made the initial discovery. TRAPPIST is the forerunner of a more ambitious facility called “SPECULOOS” that includes Cambridge as core partner, conducted by researchers of the “Cambridge Centre for Exoplanet Research” in the broad research context related to “Universal Life”. SPECULOOS is currently under construction at ESO’ Observatory of Cerro Paranal. SPECULOOS will survey 10 times more stars for planets, than TRAPPIST could do. We expect to detect dozens of additional terrestrial planets.

Michaël Gillon et al: “Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1” Nature 23rd Feb. 2017

Link to a science-fiction short story:

Cambridge Exoplanet Research Centre:

For additional information, images, videos, a graphic novel and short stories, visit

Adapted from a press release by the European Space Observatory (ESO)

An international team of astronomers has found a system of seven potentially habitable planets orbiting a star 39 light years away three of which could have water on their surfaces raising the possibility they could host life. Using ground and space telescopes, the team identified the planets as they passed in front of the ultracool dwarf star known as TRAPPIST-1. The star is around eight per cent of the mass of the Sun and is no bigger than Jupiter.

That the planets are so similar to Earth bodes well for the search for life elsewhereAmaury Triaud

The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Pluto is still an ex-planet, no matter what its fans think

Astronomy News - 23 February 2017 - 9:14am
A fresh attempt to revive full planet status for Pluto is a non-starter. Astronomer Michael Brown explains why hopes of a comeback are futile

Seven Earth-size planets found around nearby star may have water

Astronomy News - 23 February 2017 - 9:12am

The small, cool star TRAPPIST-1 is one of the best places to look for life in the Milky Way: its seven rocky planets might all have water and atmospheres

NASA Telescope Reveals Largest Batch of Earth-Size, Habitable-Zone Planets Around Single Star

Astronomy News - 23 February 2017 - 9:10am

NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are located in an area called the habitable zone, where liquid water is most likely to thrive on a rocky planet. The system sets a new record for the greatest number of habitable zone planets found outside our solar system. Any of these seven planets could have liquid water, the key to life as we know it. The exoplanet system is called TRAPPIST-1 and is only 40 light-years away. Following up on the Spitzer discovery, NASA's Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone. These observations aim at assessing the presence of puffy, hydrogen-dominated atmospheres, typical for gaseous worlds like Neptune, around these planets. In May 2016, the Hubble team observed the two innermost planets and found no evidence for such puffy atmospheres. This finding strengthened the case that the planets closest to the star are terrestrial in nature. Astronomers plan follow-up studies using NASA's upcoming James Webb Space Telescope, scheduled to launch in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet's atmosphere. Webb also will analyze planets' temperatures and surface pressures — key factors in assessing their habitability.

For illustrations and more information about the TRAPPIST-1 system, visit:

Ultracool Dwarf and the Seven Planets

Astronomy News - 23 February 2017 - 9:08am
Astronomers have found a system of seven Earth-sized planets just 40 light-years away. Using ground and space telescopes, including ESO’s Very Large Telescope, the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1. According to the paper appearing today in the journal Nature, three of the planets lie in the habitable zone and could harbour oceans of water on their surfaces, increasing the possibility that the star system could play host to life. This system has both the largest number of Earth-sized planets yet found and the largest number of worlds that could support liquid water on their surfaces.

Star's seven Earth-sized worlds set record

Astronomy News - 23 February 2017 - 9:04am

Astronomers have discovered seven Earth-sized planets orbiting a single star - a record number.

INTEGRAL Announcement of Opportunity (AO-15)

Astronomy News - 21 February 2017 - 9:23am
Proposals are solicited for observations with INTEGRAL in response to the Fifteenth Announcement of Opportunity, AO-15, issued 20 February 2017. This AO covers the period January 2018 to December 2018.

The brightest, furthest pulsar in the Universe

Astronomy News - 21 February 2017 - 9:20am

ESA's XMM-Newton has found a pulsar – the spinning remains of a once-massive star – that is a thousand times brighter than previously thought possible.