Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in […]

Why does Jupiter have rings? Jupiter’s main ring was discovered in 1979 by NASA’s passing Voyager 1 spacecraft, but its origin was then a mystery. Data from NASA’s Galileo spacecraft […]

Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is a Trojan moon, so called because it orbits at a Lagrange […]

Why is the Moon so dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, eons of constant micrometeorite bombardment have blasted away […]

One of the brightest galaxies in planet Earth’s sky is similar in size to our Milky Way Galaxy: big, beautiful Messier 81. Also known as NGC 3031 or Bode’s galaxy […]

You’d think the Pacman Nebula would be eating stars, but actually it is forming them. Within the nebula, a cluster’s young, massive stars are powering the pervasive nebular glow. The […]

What causes a blue band to cross the Moon during a lunar eclipse? The blue band is real but usually quite hard to see. The featured HDR image of last […]

This was once a beach — on ancient Mars. The featured 360-degree panorama, horizontally compressed, was taken in 2017 by the robotic Curiosity rover that explored the red planet. Named […]

What’s the sound of one laser zapping? There’s no need to consult a Zen master to find out, just listen to the first acoustic recording of laser shots on Mars. […]

This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the […]