Centauri Dreams 20 Feb 2019, 17:35 UTC It seems increasingly clear that the factors that govern what kind of a planet emerges where in a given stellar system are numerous and not always well understood. Beyond the snowline, planets draw themselves together from the ice and other volatiles available in these cold regions, so that we wind up with low-density gas or ice-giants in the outer parts of a stellar system. Sometimes. Rocky worlds are made of silicates and iron, elements that, unlike ice, can withstand the much warmer temperatures inside the snowline. But consider: While we now have 2,000 confirmed exoplanets smaller than three Earth radii, the spread in their densities is all over the map. We’re finding that other processes must be in play, and at no insubstantial level. Low-density giant planets can turn up orbiting close to their stars. Planets not so dissimilar from Earth in terms of their radius may be found with strikingly different densities in the same system, and at no great distance from each other.
Starts With a Bang! 20 Feb 2019, 15:01 UTC When it comes to the elements of the Universe, every one of them has its own unique story. Hydrogen and helium were created in the earliest stages of the Big Bang; light elements like carbon and oxygen are created in Sun-like stars; heavier elements like silicon, sulfur and iron are created in more massive stars; elements beyond iron are made when those massive stars explode in supernovae. But the most massive elements of all at the very high end of the periodic table — including platinum, gold, radon, and even uranium — owe their origins to an even rarer, more energetic process. The heaviest elements of all come from merging neutron stars, a fact that was long suspected but only confirmed in 2017. Here’s the cosmic story of how the Universe got there.
Bad Astronomy 20 Feb 2019, 14:00 UTC The NASA Mars InSight lander is now broadcasting daily weather updates!
Universe Today 20 Feb 2019, 00:04 UTC We live in a time when our spacecraft orbiting Mars at an altitude of about 300 km. can snap photos of a dust devil and transmit them back to us so we can share them on the internet. Not only that, but we have rovers wandering around on the surface taking pictures of the dust storms, too.
Parabolic Arc 19 Feb 2019, 18:52 UTC Virgin Galactic’s historic, first spaceflight, was a wonderful way for our dedicated and talented teams to close 2018. But now, with the rocket motor from that flight on show at the Smithsonian National Air and Space Museum and our first space pilots proudly wearing their FAA Commercial Astronaut Wings, we are getting ready to return VSS Unity to the black skies.
The Planetary Society Blog 19 Feb 2019, 17:02 UTC More than 4 years after launch and a half year surveying asteroid Ryugu in space, Japan's Hayabusa2 spacecraft is ready for its biggest moment yet: sample collection. The spacecraft is scheduled to touch down on Ryugu at 08:15 Japan time on 22 February (21 February 23:15 UTC, 18:15 EST). If all goes well, Hayabusa2 will gently touch Ryugu with its meter-long sample horn, fire a bullet made of tantalum into the surface, and capture the resulting cloud of dust and debris.
Starts With a Bang! 19 Feb 2019, 15:01 UTC Every so often, an idea comes along in theoretical physics that’s undeniably profound. When a single idea can solve a slew of existing puzzles in one fell swoop while simultaneously making new, testable predictions, it’s bound to generate a tremendous amount of interest. It can do more than provide a potential way forward; it can capture the imagination as well. If its predictions are borne out, it could kick off an entirely new understanding of the Universe. This was exactly the situation when physicists hit upon the idea of supersymmetry, or SUSY for short. No one knows why the fundamental particles of the Standard Model have masses that are so small compared to the Planck scale, or why the fundamental constants don’t unify, or what dark matter might be. But SUSY promised a solution to each of these, while predicting a spectrum of new particles. With the LHC’s Run II complete, we know those particles aren’t where they need to be. The dream of solving all of these problems with SUSY has vanished, and a generation of physicists must now confront that reality.
Centauri Dreams 19 Feb 2019, 13:45 UTC Recently we’ve talked about ‘standard candles,’ these being understood as objects in the sky about which we know the total luminosity because of some innate characteristic. Thus the Type 1a supernova, produced in a binary star system as material from a red giant falls onto a white dwarf, causing the smaller star to reach a mass limit and explode. These explosions reach roughly the same peak brightness, allowing astronomers to calculate their distance.
Mullard Space Science Laboratory Astronomy Blog 18 Feb 2019, 18:00 UTC Cosmic rays are rays of energetic particles and radiation, with their composition in our own Galaxy being dominated by protons. Ellis Owen, a final-year PhD student working on cosmic rays, star-formation and galaxy evolution, tells us about his research on them.