NGC 6240: Merging Galaxies
18.06.2009

NGC 6240 offers a rare glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision is located a mere 400 million light-years away in the constellation Ophiuchus. One of the brightest...

Along the Cygnus Wall
3.07.2014

The prominent ridge of emission featured in this vivid skyscape is known as the Cygnus Wall. Part of a larger emission nebula with a distinctive shape popularly called The North America Nebula, the ridge spans about 10 light-years along an outline that suggests the western coast of Mexico.

The Heart and Soul Nebulas
15.01.2019

Is the heart and soul of our Galaxy located in Cassiopeia? Possibly not, but that is where two bright emission nebulas nicknamed Heart and Soul can be found. The Heart Nebula, officially dubbed IC 1805 and visible in the featured image on the bottom right, has a shape reminiscent of a classical heart symbol.

The Changing Surface of Fading Betelgeuse
17.02.2020

Besides fading, is Betelgeuse changing its appearance? Yes. The famous red supergiant star in the familiar constellation of Orion is so large that telescopes on Earth can actually resolve its surface -- although just barely.

APOD: 2025 September 18 Б Comet C/2025 R2 SWAN
18.09.2025

A new visitor from the outer Solar System, comet C/2025 R2 (SWAN) also known as SWAN25B was only discovered late last week, on September 11. That's just day before the comet reached perihelion, its closest approach to the Sun.

A Cerro Tololo Sky
14.05.2001

High atop a Chilean mountain lies one of the premier observatories of the southern sky: Cerro Tololo. Pictured above is one of the premier telescopes of the Cerro Tololo Inter-American Observatory (CTIO) and of the past quarter-century: the 4-meter Blanco Telescope.

Clusters and Nebulae of the Hexagon
4.04.2003

At first, the bright stars of the large asterism known as the (northern) Winter Hexagon might be hard to pick out in this gorgeous deep sky mosaic from December 2002. But placing your cursor...

Black Hole Candidate Cygnus X 1
11.08.2008

Is that a black hole? Quite possibly. The Cygnus X-1 binary star system contains one of the best candidates for a black hole. The system was discovered because it is one of the brightest...

The Galactic Core in Infrared
17.01.2015

What's happening at the center of our Milky Way Galaxy? To help find out, the orbiting Hubble and Spitzer space telescopes have combined their efforts to survey the region in unprecedented detail in infrared light. Milky Way's center because visible light is more greatly obscured by dust.

A 212 Hour Exposure of Orion
29.03.2020

The constellation of Orion is much more than three stars in a row. It is a direction in space that is rich with impressive nebulas. To better appreciate this well-known swath of sky, an extremely long exposure was taken over many clear nights in 2013 and 2014.