Space Fellowship 13 Mar 2018, 06:22 UTC Is it possible to capture the entire plane of our galaxy in a single image? Yes, but not in one exposure — and it took some planning to do it in two. The top part of the featured image is the night sky above Lebanon, north of the equator, taken in 2017 June. The image was taken at a time when the central band of the Milky Way Galaxy passed directly overhead. The bottom half was similarly captured six months later in latitude-opposite Chile, south of Earth’s equator.
Tom's Astronomy Blog 13 Mar 2018, 04:04 UTC A beautiful look at the Saturn moon Dione and a great look at a rayed crater. Easy to see why the rays are so bright being made of what we would think of as “super hard water ice”.I believe this crater is Creusa. The rays are as you would expect material ejected out after an impact, in this case water ice (we think). These rayed craters on Dione may be less than about 50 M/yr’s -old (1). Yes, sounds like a long time but really not so much when you think about things on a solar system-evolutionary time scale. Cassini has shown us that at least parts of the Saturn system are quite active more so than many people first belived.NASA – Cassini captured this striking view of Saturn’s moon Dione on July 23, 2012. Dione is about 698 miles (1,123 kilometers) across. Its density suggests that about a third of the moon is made up of a dense core (probably silicate rock) with the remainder of its material being water ice. At Dione’s average temperature of -304 degrees Fahrenheit (-186 degrees Celsius), ice is so hard it behaves like rock.The image was taken with Cassini’s narrow-angle camera at a ...
Cosmic Diary 12 Mar 2018, 18:01 UTC The big crater is ~400 m (1/4 mile) across. Wind blows sediment from the top to the bottom of the view, making some dune-like features (TARs, really) at the top and inside the crater. The rim at the top of the crater has a set of hills with a dip in between them, which allows wind and sediment to be funneled into the crater through a narrow valley. Once inside the crater, the wind expands laterally, so that some of the dune-like features form arcs, like ripples that form after you throw a rock into a pond.
Sky and Telescope 12 Mar 2018, 16:19 UTC In the planet–planet scattering model of solar-system formation, planets are thought to initially form in closely packed systems. Over time, planets in a system perturb each other, eventually entering an instability phase during which their orbits cross and the planets experience close encounters. During this “scattering” process, any exomoons that are orbiting giant planets can be knocked into unstable orbits directly by close encounters with perturbing planets. Exomoons can also be disturbed if their host planets’ properties or orbits change as a consequence of scattering.
Scientific American 12 Mar 2018, 10:45 UTC A maverick group of astronomers is proposing to radically reshape one of NASA’s most successful missions in the modern era, the New Horizons probe that flew by Pluto in 2015 and is now continuing its voyage into the depths of the outer solar system.
EarthSky Blog 11 Mar 2018, 10:59 UTC Here’s the good news: Astronomers have made the most precise measurement to date of the rate at which the universe is expanding since the Big Bang. Here’s the possibly unsettling news: The new numbers remain at odds with independent measurements of the early universe’s expansion, which could mean that there is something unknown about the makeup of the universe. Is something unpredicted going on in the depths of space? Adam Riess is a Nobel Laureate and Bloomberg Distinguished Professor at Johns Hopkins University. He said: The community is really grappling with understanding the meaning of this discrepancy. Riess leads a team of researchers using the Hubble Space Telescope to measure the expansion rate of the universe. He shared a Nobel Prize in 2011 for the discovery of the accelerating universe. The team, which includes researchers from Hopkins and the Space Telescope Science Institute, has used the Hubble Space Telescope over the past six years to refine the measurements of the distances to galaxies, using stars as milepost markers. Those measurements are used to calculate how fast the universe expands with time, a value known as the Hubble constant.
SPACE.com 10 Mar 2018, 13:19 UTC "Cosmos" host and astrophysicist Neil deGrasse Tyson recently shot down the ideas of anyone who still thinks the Earth is flat. In a new YouTube video on the scientist's StarTalk channel, he used examples ranging from space observations to ancient Greek experiments in a conversation with stand-up comedian Chuck Nice.
Lights in the Dark 9 Mar 2018, 21:28 UTC The eye in the sky sees all…especially when that eye is the HiRISE camera on the Mars Reconnaissance Orbiter! Here’s an image of a crater known as Santa Maria, taken from over 150 miles above the Martian surface by the MRO…and if you look carefully at the lower right portion of the crater rim you can see a small grey object that casts a bit of a shadow. That’s the rover Opportunity, which has been investigating the area around Santa Maria for the past several months and was using its robotic arm to take close-up shots of a small nearby rock when the image above was acquired.