Astro Blog

http://www.sciencemag.org/news/2018/05/asteroid-came-another-solar-system-and-it-s-here-stay Source:   By Daniel Clery, Science Magazine. Excerpt: While astronomers around the world had their eyes fixed last year on ‘Oumuamua, a lump of rock from another planetary system that whizzed through ours, little did they know that another interstellar interloper was quietly living among us. And this one appears to have been here for billions of years. Astronomers first spotted the object, an asteroid called 2015 BZ509 that is orbiting close to Jupiter, in 2014. They knew it was unusual because it was traveling around the solar system in the opposite direction as almost everything else. ...Astronomers have found other objects in “retrograde” orbits, perhaps knocked off course by passing too close to a giant planet, but 2015 BZ509’s orbit was the weirdest of all because it is also elongated and out of alignment with the planets and other bodies. To find out why, a pair of astronomers ran...

https://www.washingtonpost.com/news/speaking-of-science/wp/2018/05/07/yes-pluto-is-a-planet/ Source:   David Grinspoon and Alan Stern, The Washington Post. Excerpt: Three years ago, NASA’s New Horizons, the fastest spaceship ever launched, raced past Pluto, spectacularly revealing the wonders of that newly seen world. This coming New Year’s Eve — if all goes well on board this small robot operating extremely far from home — it will treat us to images of the most distant body ever explored, provisionally named Ultima Thule. We know very little about it, but we do know it’s not a planet. Pluto, by contrast — despite what you’ve heard — is. Why do we say this? ...We use “planet” to describe worlds with certain qualities. When we see one like Pluto, with its many familiar features — mountains of ice, glaciers of nitrogen, a blue sky with layers of smog — we and our colleagues quite naturally find ourselves using the word “planet” to describe it and compare it to other planets that ...

https://www.nytimes.com/2018/05/01/science/gaia-map-milky-way.html Source:   By Dennis Overbye, The New York Times. Excerpt: ...astronomers in Europe released a three-dimensional map of the Milky Way. It is the most detailed survey ever produced of our home galaxy. It contains the vital statistics of some 1.3 billion stars — about one percent of the entire cosmic panoply of which Earth and the sun are part. Not to mention measurements of almost half a million quasars, asteroids and other flecks in the night. Analyzing all these motions and distances, astronomers say, could provide clues to the nature of dark matter. The gravity of that mysterious substance is said to pervade space and sculpt the arrangements of visible matter. Gaia’s data could also reveal information about the history of other forces and influences on our neighborhood in the void. And it could lead to a more precise measurement of a historically troublesome parameter called the Hubble constant, which describes...