Astro Blog

Source:   Maria Zuber, PBS Science Friday Podcast: Twin GRAIL spacecraft on a mission to study lunar gravity are nearing the end of their almost four month journey. The probes are expected to reach the moon on New Year's Eve and New Year's Day. GRAIL's principal investigator, Maria Zuber of MIT talks about the data they hope to collect. www.sciencefriday.com/program/archives/201112302

Source:   Joyce Sutphen, The Writ'ers Almanac Excerpt: Astronomer Edwin Hubble announced the discovery of other galaxies on this date in 1924. At the time it was thought that our Milky Way galaxy represented the entirety of the universe. Hubble was studying the Andromeda Nebula .... Hubble crunched the numbers and realized that the star he was observing was 800 thousand light years away, more than eight times the distance of the farthest star in the Milky Way. ...he realized that the "cloud of gas" he'd been observing was really another vast galaxy that was very far away.... writersalmanac.publicradio.org/index.php

Source:    Amy Shira Teitel, Universe Today Excerpt:  …Since 2006, astronomers have been tracking smaller secondary moons that our own Earth-Moon system captures; these metre-wide moons stay for a few months then leave. But what if the Earth actually had a second permanent moon today? How different would life be?   ... For his two-mooned Earth thought experiment, Comins proposes that our Earth-Moon system formed as it did — he needs the same early conditions that allowed life to form — before capturing a third body. This moon, which I will call Luna, sits halfway between the Earth and the Moon.  …Eventually, the Moon and Luna would collide; like the Moon is now, both moons would be receding from Earth.... www.universetoday.com/92148/what-if-the-earth-had-two-moons/

Source:   Dan Vergano, USA TODAY Excerpt: …some solace comes from the Kepler space telescope team's estimate that just in our Milky Way galaxy alone, some 500 million planets likely orbit inside their star's habitable zone. "We have many candidates in that region," said Kepler principal scientist William Borucki of NASA's Ames Research Center in Moffett Field, Calif., at a briefing unveiling Kepler-22b to his colleagues earlier this month. At his briefing, Borucki showed a chart depicting more than 50 possible habitable zone planets, … www.usatoday.com/tech/science/columnist/vergano/story/2011-12-18/kepler-habitable-planets/52031444/1

Source:    NASA RELEASE: 11-402 Excerpt:  NASA's Voyager 1 spacecraft has entered a new region between our solar system and interstellar space.  ...Although Voyager 1 is about 11 billion miles (18 billion kilometers) from the sun, it is not yet in interstellar space.  ...Scientists previously reported the outward speed of the solar wind had diminished to zero in April 2010, marking the start of the new region.  …"We've been using the flow of energetic charged particles at Voyager 1 as a kind of wind sock to estimate the solar wind velocity," said Rob Decker,... "We've found that the wind speeds are low in this region and gust erratically. For the first time, the wind even blows back at us. We are evidently traveling in completely new territory. ...For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager  www.nasa.gov/home/hqnews/2011/dec/HQ_11-402_AGU_Voyager.html

Source:   C aleb A. Scharf, Scientific American Excerpt: Gas giant planets are among the most beautiful and awe-inspiring worlds. …The major bulk of these planets, and their cousins around other stars, consists of primordial hydrogen and helium – vast envelopes of matter cocooning their cores and rendering them inaccessible to us. The pressures deep down in a planet like Jupiter can reach a hundred million times those on Earth’s surface, and temperatures can be tens of thousands of Kelvin. …At such huge pressures, hydrogen becomes a liquid, even though temperatures are high. …A new paper showed up this past week by Wilson and Militzer that suggests … if a gas giant planet forms around a large rocky proto-planet (perhaps 10 times the mass of the Earth), the liquid metallic hydrogen that eventually envelops that core may also melt, or dissolve it. ... bigger, hotter “super-Jupiter” exoplanets may appear more abundant in heavy elements to our astronomical instruments not because t