In the early 17th century, Galileo Galilei peered through his telescope and reported the planet Saturn as having ears. He was the first to peer at the planet’s dazzling ring system, now known to be composed of tiny orbiting particles of ice and dust. Observations of the rings are still yielding surprises. Recent images from NASA’s Cassini spacecraft show a luminous dot speeding within the G ring, one of the planet’s faintest, least-understood rings. The orbiting body is a moon about 0.5 kilometers (0.3 miles) wide. Particles shed by this moonlet—and perhaps others like it yet to be discovered—make up the G ring. Prior to this discovery, the G ring was the only one of Saturn’s dusty rings that was not known to host a moon.

To learn about other recent astronomical discoveries, visit the Science Bulletins website.

The telescope technique of adaptive optics is rapidly advancing, allowing unprecedented ground-based views of distant galaxies, stars, and planets both inside and outside our Solar System. Adaptive optics reduces the greatest obstacle to a clear picture for telescopes viewing the sky from Earth: interference from our own planet’s atmosphere.

Astronomers with the European Southern Observatory recently used adaptive optics to spot details in the core of NGC 253, one of the brightest and dustiest spiral galaxies in the sky. The new image shows that the core is packed with massive nurseries of young stars. The observations also suggest that the supermassive black hole at this galaxy’s center is similar to the one at the center of the Milky Way. Learning more details about our galactic neighbors allows researchers to better understand how our own galaxy compares to the crowd.

To learn about other recent astronomical discoveries, visit the Science Bulletins website.

In 1999, the remains of an exploded star—the supernova remnant Cassiopeia A—was among the first objects on which the spaceborne Chandra telescope trained its X-ray eye. Chandra has been following these stellar leftovers ever since. Now, a decade of detection has produced a time-lapse movie of the evolution of the supernova remnant. It has been expanding since 1680, when its precursor star exploded.

Astrophysicists have also used the data from Chandra and other telescopes to reconstruct the first 3D multiwavelength fly-through of a supernova remnant. The reconstruction shows that the material from the outer layers of the star ejected radially, resulting in Cassiopeia A having an overall spherical shape. Scientists think the inner parts of the star were ejected as pointed jets. The central star then collapsed to form a dense neutron star at the center of the stellar remains. By mapping these evolutionary stages, astronomers can better understand how stars evolve and die.

To see more, visit the latest AMNH Astro Bulletin.