An analysis of gravity and topography data from the Saturnian moon Titan obtained by NASA’s Cassini spacecraft suggests there could be something unexpected about the moon’s outer ice shell. The findings, published on Aug. 28 in the journal Nature, suggest that Titan’s ice shell could be rigid, and that relatively small topographic features on the surface could be associated with large ice “roots” extending into the underlying ocean.
The study was led by planetary scientists Douglas Hemingway and Francis Nimmo at the University of California, Santa Cruz, who used data from Cassini. The researchers were surprised to find a counterintuitive relationship between gravity and topography. (more…)
A study of 544 star-forming galaxies shows that disk galaxies like our own Milky Way reached their current state as orderly rotating pinwheels much later than previously thought, long after much of the universe’s star formation had ceased.
Galaxies are in no hurry to grow up, a team of astronomers has discovered. A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA’s Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.
Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way. Until now, it had not been clear how a galaxy’s organization and internal motion change over time, said Benjamin Weiner, assistant astronomer at the UA Steward Observatory and co-author of the paper describing the findings, which are published in The Astrophysical Journal. (more…)
Dissolution or creation of huge gypsum deposits changed sulfate content of the oceans
Scientists have discovered a potential cause of Earth’s “icehouse climate” cooling trend of the past 45 million years. It has everything to do with the chemistry of the world’s oceans.
“Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change,” says geoscientist Ulrich Wortmann of the University of Toronto, lead author of a paper reporting the results and published this week in the journal Science.
“We’ve established a new framework that helps us better interpret evolutionary trends and climate change over long periods of time. The study focuses on the past 130 million years, but similar interactions have likely occurred through the past 500 million years.” (more…)
*Spread highest in urbanized and agricultural habitats*
After its initial appearance in New York in 1999, West Nile virus spread across the United States in just a few years and is now well established throughout North and South America.
Both the mosquitoes that transmit it and the birds that are important hosts for the virus are abundant in areas that have been modified by human activities.
As a result, transmission of West Nile virus is highest in urbanized and agricultural habitats. (more…)
For many lizards, global climate change is a matter of life and death.
After decades of surveying Sceloporus lizard populations in Mexico, an international research team has found that rising temperatures have driven 12 percent of the country’s lizard populations to extinction.
