When astronomers add up the mass of all the normal matter in the present-day universe, about a third of it can’t be found. Where is it?
The background of this image is from a supercomputer simulation. It shows a honeycomb-like structure of the universe, sometimes called the "cosmic web." The simulation reveals how key components of the universe - including large filaments of warm and hot gas known as the WHIM - evolved over time. Scientists think the missing normal matter of our universe might be in the WHIM. Image via Springel et al. (2005)/ NASA
/ CXC/ CfA/ Kovács et al.
Never-before-seen footage of night skies over the HAARP antenna array in remote northern Alaska.
Expect higher-than-usual tides a day or two after the February 19, 2019, full supermoon.
Photo by John Lloyd Griffith
Regulus, brightest star in Leo the Lion, is now rising in the east after sunset. You might not notice it, but stargazers know that, when Regulus appears in this way, spring is near.
Regulus and Leo I dwarf galaxy. Image via Russell Croman
Our sun’s solar flares are an incredible natural phenomenon, but now astronomers have observed a flare on a young star that almost defies belief. It’s 10 billion times more powerful than any seen on our sun!
This year’s El Niño is likely to be weak, with little influence on weather through early spring, say NOAA forecasters.
Image via NOAA.
A new study suggests that Europe’s ancient megaliths, including Stonehenge, might have stemmed from a single hunter-gatherer culture in what’s now northwestern France.
Stonehenge - on the Salisbury Plain in England - as captured by EarthSky Facebook friend Buddy Puckhaber of South Carolina. Thank you, Buddy.
Mars has long been thought to be a geologically dead world. Could there still be volcanic activity beneath its surface? A subsurface lake at Mars’ south pole suggests that possibility.
Is there current volcanic activity on Mars? A subsurface lake beneath the south polar ice cap may indicate that there is. Image via NASA.
A remarkable set of fossil spiders found in South Korea display reflective eyes.
Two of the fossil specimens discovered in Korea had reflective eyes, a feature still apparent under light. Image via Paul Selden .