Antares and Rho Ophiuchi
22.09.1997

Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.

Abell 3627 in the Great Attractor
17.02.1996

Are these galaxies near the center of the largest gravitationally bound concentration of mass yet known? Previously, the cluster of galaxies known as Abell 3627 was largely unstudied because dust in the disk of our own Galaxy obscured much of its light.

Antares and Rho Ophiuchi
21.05.2000

Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.

Elliptical Galaxy M87
16.06.2004

Elliptical galaxy M87 is a type of galaxy that looks much different than our own Milky Way Galaxy. Even for an elliptical galaxy, though, M87 is peculiar. M87 is much bigger than an average...

Reflections on the 1970s
2.10.2003

The 1970s are often overlooked. In particular, the beautiful grouping of reflection nebulae NGC 1977, NGC 1975, and NGC 1973 in Orion are often overlooked in favor of the substantial stellar nursery better known as the Orion Nebula.

Reflections on the 1970s
18.12.2014

The 1970s are sometimes ignored by astronomers, like this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula.

Reflections on the 1970s
12.01.2016

The 1970s are sometimes ignored by astronomers, like this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula.

Reflections on the 1970s
1.02.2023

The 1970s are sometimes ignored by astronomers, like this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula.

APOD: 2025 October 7 Б SN Encore: A Second Supernova Seen Several Times
6.10.2025

Now a second supernova in this same galaxy is repeating. The cause is the gravitational lens effect of a massive foreground cluster of galaxies (MACS J0138) -- it creates multiple images of a perfectly aligned background galaxy (MRG-M0138). What's particularly interesting is that this background galaxy has young stars that keep blowing up.

The Keyhole Nebula in Infrared
13.06.2000

About three million years ago, the stars in the Keyhole Nebula began to form. The above picture of the Keyhole Nebula, also known as the Carina Nebula or NGC 3372, shows in infrared light many facets of this dramatic stellar nursery which lies only 9,000 light-years away.