SUNSET: 
Astronomers Discover Galactic “Fossil” Inside the Milky Way
Thousands of stars that once belonged to an ancient galaxy are inside our own.
A Dark Matter-less Galaxy, Explained (Maybe)
An international team of astronomers has explained the lack of dark matter in a distant dwarf galaxy — another galaxy stole it.
The Arecibo Telescope Has Collapsed [Video]
The Arecibo telescope in Puerto Rico has collapsed less than two weeks after officials announced it was too dangerous to attempt repairs.
Gamma-ray Flash Heralds Birth of a Magnetar
What happens when two neutron stars don't add up to a black hole?
Iconic Arecibo Telescope Damaged, To Be Dismantled
The iconic Arecibo telescope, damaged by two cable failures within three months, is beyond repair.
The Case of the Blue Ring Nebula
After 16 years, astronomers have figured out the origin of a strange ring of ultraviolet light, and shed light on a common — but rarely observed — event.
Star Clusters Reveal the "Kraken" in the Milky Way's Past
Astronomers have reconstructed the Milky Way's merger history, finding that our galaxy has absorbed five large satellite galaxies in the last 12 billion years.
How Big Is Betelgeuse Really?
Knowing Betelgeuse’s size is crucial to understanding its recent bizarre behavior — and predicting when it will go supernova. But it’s harder to figure out than you might think.
Magnetars Make Some — Maybe All — Mysterious Radio Flashes
In-depth analysis of a flash of radio waves coming from a Milky Way magnetar have convinced astronomers: Magnetars produce at least some fast radio bursts.
60-second Astro News: Mature Infant Galaxies & A Possibly Rogue Planet
This week in astronomy news: Distant galaxies that look older than they are and a terrestrial planet that might be drifting through our galaxy.
Astronomers Chart Star Formation History, Glimpse Fate of the Universe
Astronomers have tallied how star-making material evolved over cosmic time — and they've predicted how long stars will keep forming before the universe goes dark.
Moon’s Magnetism Might Have Protected Earth
The Moon's magnetic field, now long gone, might once have shielded Earth from the young Sun's radiation.
Calling on Amateur Astronomers: Observe Venus!
The Mercury-bound BepiColombo spacecraft will fly by Venus on October 15th, and the mission is asking amateurs for their help.
How Planetary Nebulae Get Their Shapes
New research shows why these celestial gems range in shape from spirals to butterflies.
Comets Have (Ultraviolet) Aurora, Too
Observations from the European Space Agency’s Rosetta spacecraft show that Comet 67P/Churyumov-Gerasimenko has its own aurora.
The Sun’s Activity Cycle Is Stabilizing
Solar Cycle 25 is here, and forecasts suggest the next decade of the Sun’s activity will mimic the last one — halting a 40-year trend.
Hubble Images Reveal Dark Matter Problem
Astronomers studying Hubble Space Telescope images of massive galaxy clusters have uncovered a potential problem with dark matter.
Astronomers Map Andromeda’s Halo
Astronomers have observed 43 quasars in back of our sister galaxy, Andromeda, using the distant beacons to map its halo of hot gas.
See the Invisible: A Gallery of Magnetic Fields
Magnetic fields affect everything from star formation to galaxy evolution. View a gallery of images that show magnetism's role.
Hubble Captures Comet NEOWISE
The Hubble Space Telescope imaged the famous comet on August 8th.
