APOD is 20 Years Old Today
16.06.2015

Welcome to the vicennial year of the Astronomy Picture of the Day! Perhaps a source of web consistency for some, APOD is still here. As during each of the 20 years of selecting images...

XMM Launched
21.12.1999

X-ray astronomy entered a golden age earlier this month with the successful launch of the X-ray Multi-Mirror (XMM) satellite. XMM's three huge telescope barrels each hold 58 concentric cylindrical mirrors, together totaling a surface area rivaling a tennis court.

Edwin Hubble Discovers the Universe
26.04.2020

How big is our universe? This very question, among others, was debated by two leading astronomers 100 years ago today in what has become known as astronomy's Great Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many.

Ghosts in Cassiopeia
31.10.2025

Halloween is an astronomy holiday and spooky shapes always seem to lurk in planet Earth's night skies. In fact, near the center of this telescopic view toward the constellation Cassiopeia these swept-back interstellar clouds IC 59 (left) and IC 63 look ghostly on a cosmic scale.

Simulated Supergiant Star
22.12.2000

Looking for that perfect holiday gift for an astronomer? Consider this "star in a box". Of course, the box is actually a computational box consisting of a three dimensional grid of points, and the star is a virtual one whose physical properties and internal dynamics are numerically simulated at the points on the grid.

SOFIA s Window Seat
25.02.2006

Earlier this month, a 2.5-meter diameter infrared telescope was permanently assigned a window seat, looking through this opening in the fuselage of a historic Boeing 747 aircraft. The telescope mirror, about the size of the Hubble Space Telescope mirror, is protected by a red covering.

UKIRT: Aloha Orion
6.01.2005

At the edge of a dense molecular cloud, filaments of gas, cosmic dust, and a multitude of young stars beckon in this penetrating image of the Orion Nebula. Alluring structures in the well-known star...

Waves of the Great Lacerta Nebula
14.09.2022

It is one of the largest nebulas on the sky -- why isn't it better known? Roughly the same angular size as the Andromeda Galaxy, the Great Lacerta Nebula can be found toward the constellation of the Lizard (Lacerta).

Bright Bolide
11.10.2008

On September 30, a spectacular bolide or fireball meteor surprised a group of amateur astronomers enjoying dark night skies over the Oklahoma panhandle's Black Mesa State Park in the Midwestern US. Flashing past...

The Nebula And The Neutron Star
25.10.2000

The lonely RX J1856.5-3754 was formed from the collapsed core of an exploding star. At a distance of 180 light-years it is the closest known neutron star. More massive than...