In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for […]

How does the sky turn dark at night? In stages, and with different characteristic colors rising from the horizon. The featured image shows, left to right, increasingly late twilight times […]

All of the other aurora watchers had gone home. By 3:30 am in Iceland, on a quiet September night, much of that night’s auroras had died down. Suddenly, unexpectedly, a […]

Intuitive Machines’ robotic lander Odysseus has accomplished the first U.S. landing on the Moon since the Apollo 17 mission in 1972. Launched on a SpaceX rocket on February 15, the […]

This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Centered and moving upward in the sharply detailed color composite its thin, bright, braided filaments are […]

Big, bright, beautiful spiral, Messier 106 dominates this cosmic vista. The nearly two degree wide telescopic field of view looks toward the well-trained constellation Canes Venatici, near the handle of […]

The bird is bigger than the peak. Nicknamed for its avian shape, the Seagull Nebula is an emission nebula on the night sky that is vast, spanning an angle over […]

When galaxies collide, how many stars are born? For AM1054-325, featured here in a recently released image by the Hubble Space Telescope, the answer is millions. Instead of stars being […]

What’s happening near the Sun? To help find out, NASA launched the robotic Parker Solar Probe (PSP) to investigate regions closer to the Sun than ever before. The PSP’s looping […]

Is this one galaxy or two? This question came to light in 1950 when astronomer Arthur Hoag chanced upon this unusual extragalactic object. On the outside is a ring dominated […]