Halloween and the Ghost Head Nebula
31.10.2010

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With a modern calendar, however, the real cross-quarter day will occur next week.

NGC 6791: An Old, Large Open Cluster
12.01.2000

NGC 6791 is one of the oldest and largest open clusters of stars known. But how did it get so dirty? Open star clusters usually contain a few hundred stars each less than a billion years old.

APOD: 2024 August 4 Б Gaia: Here Comes the Sun
4.08.2024

What would it look like to return home from outside our galaxy? Although designed to answer greater questions, data from ESA's robotic Gaia mission is helping to provide a uniquely modern perspective on humanity's place in the universe.

APOD: 2025 July 2 Б Milky Way Through Otago Spires
2.07.2025

Does the Milky Way always rise between these two rocks? No. Capturing this stunning alignment took careful planning: being in the right place at the right time. In the featured image taken in June...

A Quasar Portrait Gallery
25.11.1996

QUASARs (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded - to be visible at such extreme distances of billions of light-years they must emit prodigious amounts of energy. Where does the energy come from?

Halloween and the Ghost Head Nebula
31.10.2007

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week.

Halloween and the Ghost Head Nebula
31.10.2001

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week.

Blue Straggler Stars in Globular Cluster M53
7.02.2021

If our Sun were part of this star cluster, the night sky would glow like a jewel box of bright stars. This cluster, known as M53 and cataloged as NGC 5024, is one of about 250 globular clusters that survive in our Galaxy.

APOD: 2025 July 3 Б Nova V462 Lupi Now Visible
3.07.2025

If you know where to look, you can see a thermonuclear explosion from a white dwarf star. Possibly two. Such explosions are known as novas and the detonations are currently faintly visible with the unaided eye in Earth's southern hemisphere -- but are more easily seen with binoculars.

Accretion Disk Simulation
27.09.2002

Don't be fooled by the familiar symmetry. The graceful spiral structure seen in this computer visualization does not portray winding spiral arms in a distant galaxy of stars. Instead, the graphic shows spiral...