Scientists have been saying for some time now that helium should be readily detectable in the atmospheres of gas giant planets -- after all, this is the second-most common element in the universe, and we know it is plentiful at Jupiter and Saturn. The problem has been how to detect it, an issue which this morning's story brings into sharp relief. At the University of Exeter (UK), Jessica Spake has put data from the Hubble telescope's Wide Field Camera 3 to good use, finding an abundance of helium in the upper atmosphere. The planet in question is the puffy WASP-107b, and this marks the first helium detection of the inert gas on an exoplanet. Some 200 light years from Earth in the constellation Virgo, WASP-107b shows little similarity to anything in our own Solar System. It was discovered in 2017 and is one of the lowest density planets yet found, a world that, although roughly the same size as Jupiter, has only 12 percent of its mass. In a tight six-day orbit around its K-class...

Scaling up our space telescopes calls for new thinking. Consider this: The Hubble telescope has a primary mirror of 2.4 meters. The James Webb Space Telescope takes us to 6.5 meters. But as we begin to get results from missions like TESS and JWST (assuming the latter gets off safely), we're going to need much more to see our most interesting targets. Imagine what could be done with a 30-meter space telescope, and ponder the challenge of constructing it. This is what Cornell University's Dmitry Savransky has been doing, developing a NIAC study that looks at modular design and self-assembly in space. Savransky's notions take me back to a much earlier era, when people like Bob Forward talked about massive structures in space that dwarf any engineering project we've yet attempted. Forward saw these projects -- his vast Fresnel lens between the orbits of Saturn and Uranus 1000 kilometers in diameter, for example -- as ultimately achievable, but his primary concern was to be sure the...

Avi Loeb's always interesting work has recently taken us into the realm of target selection for exoplanet surveys. Where should we be putting our time and money in the search for life elsewhere, and what can we do to maximize both the credibility of the investigation and the funding that it demands? These sound like pedestrian matters compared to the excitement of discovery -- finding Proxima b was a lot more exciting than watching any congressional committee debate over NASA's priorities. But Proxima Centauri b, that fascinating world around the nearest star, fits neatly into this narrative, for reasons that contrast nicely with its own nearest neighbors, Centauri A and B. The Centauri stars are an obvious target, and one that Loeb has devoted considerable time to assessing, given his deep involvement with Breakthrough Starshot's study of a mission there. If we find planets around Centauri A or B, are they our priority? Just where does Proxima b fit in? And what of fascinating...

Water delivery to the inner Solar System is crucial for life to develop, for worlds like our own must have formed dry, well within the 'snowline.' We need a mechanism to bring volatiles from the ice-rich regions beyond 3 AU or so, and while much attention has been paid to comets, we've been learning more about asteroids as a second delivery option, for isotopic measurements have shown that Earth's water has similarities to water bound up in carbonaceous asteroids. Focusing on asteroid delivery, Pete Schultz (Brown University) and colleague Terik Daly, a postdoctoral researcher at Johns Hopkins University, have confronted the issues raised by early system impacts in a series of experiments. The results appear in the journal Science Advances. Says Schultz: "Impact models tell us that impactors should completely devolatilize at many of the impact speeds common in the solar system, meaning all the water they contain just boils off in the heat of the impact. But nature has a tendency to...

I usually get up while it’s still dark and take a walk. The idea is to shake the night’s dreams out of my head, listen to the birds waking up and pull in a lot of fresh air, all conducive to thinking about what I want to write that day. Last fall I kept noticing the glow before morning twilight that marked the zodiacal cloud, faint enough to be lost in moonlight and challenging to see when competing with city lights. But catch the right conditions and its diffuse glow is apparent, as in the photograph below, a striking example of zodiacal light’s effect. Image: Sometimes mistaken for light pollution, zodiacal light is sunlight that is reflected by zodiacal dust. It is most visible several hours after sunset on dark, cloudless nights surrounding the spring and fall equinoxes, when the Earth's equator is aligned with the plane of the solar system. Credit: Malcol. What we’re seeing, especially at times when the ecliptic is at its largest angle to the horizon, hence autumn and spring, is...

As we await the launch of the Transiting Exoplanet Survey Satellite, I want to pause this morning to remind everyone of another significant mission: CHEOPS (CHaracterising ExOPlanet Satellite). The decade ahead is going to be an exciting one for exoplanet discovery, given that we have TESS about ready to go, JWST in the pipeline despite its problems, and CHEOPS expected to launch in 2019. Eleven European nations are involved in CHEOPS, a European Space Agency 'S-class' mission that will study exoplanetary transits. Image: Artist's impression of CHEOPS at work. Credit: ESA. In 2026, we can look forward to ESA's PLAnetary Transits and Oscillations of stars (PLATO) mission, which will study up to a million stars in search of planetary transits, with the emphasis on rocky planets in the habitable zone. In 2028, we have the ARIEL mission (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) to anticipate (see ARIEL: Focus on Exoplanet Atmospheres). What a run of space-based...