Category Astronomy/Space

This Hubble image shows the central region of a spiral galaxy known as NGC 247.

NGC 247 is a small spiral galaxy in the southern constellation of Cetus (The Whale). Lying at a distance of around 11 million light-years from us, it forms part of the Sculptor Group, a loose collection of galaxies that also contains the more famous NGC 253 (otherwise known as the Sculptor Galaxy).

NGC 247’s nucleus is visible here as a bright, whitish patch, surrounded by a mixture of stars, gas and dust. The dust forms dark patches and filaments that are silhouetted against the background of stars, while the gas has formed into bright knots known as H II regions, mostly scattered throughout the galaxy’s arms and outer areas.

This galaxy displays one particularly unusual and mysterious feature—it is not visibl...

This scene from NASA’s Mars rover Opportunity shows “Wharton Ridge,” which forms part of the southern wall of “Marathon Valley” on the rim of Endeavour Crater. The ridge’s name honors the memory of astrobiologist Robert A. Wharton (1951-2012). The scene is presented in approximately true color. Credits: NASA/JPL-Caltech/Cornell/Arizona State Univ.

Opportunity Mars rover will drive down a gully carved long ago by a fluid that might have been water, according to the latest plans for the 12-year-old mission. No Mars rover has done that before. The longest-active rover on Mars also will, for the first time, visit the interior of the crater it has worked beside for the last 5 years. These activities are part of a 2-year extended mission that began Oct...

Stock image. A new study presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. Credit: © robert / Fotolia

A new study casts light on how young, hot stars ionize oxygen in the early universe and the effects on the evolution of galaxies through time. It presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. The strength of doubly ionized oxygen increases going back in time, while the strength of singly ionized oxygen increases up to 11 billion years ago and then decreases for the remaining 1 to 2 billion years.

The cause of the two different evolutions is due to the changing physical conditions inside star-forming galaxies...

Stephanie Olson and Tim Lyons next to an image of visualizations of sulfate concentrations (top) and methane destruction (bottom) from their biogeochemical model of Earth’s ocean and atmosphere roughly one billion years ago.

For at least a billion years of the distant past, planet Earth should have been frozen over but wasn’t. Scientists thought they knew why, but a new modeling study from the Alternative Earths team of the NASA Astrobiology Institute has fired the lead actor in that long-accepted scenario. Humans worry about greenhouse gases, but between 1.8 billion and 800 million years ago, microscopic ocean dwellers really needed them. The sun was 10 to 15% dimmer than it is today – too weak to warm the planet on its own...