An Airglow Fan from Lake to Sky
27.01.2016

Why would the sky look like a giant fan? Airglow. The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured last summer next to Bryce Canyon in Utah, USA.

Comet Ikeya Zhang over Tenerife
26.03.2002

Comet Ikeya-Zhang has become bright enough to stand out in the night sky. Discovered February 1, the comet has now just rounded the Sun and has likely attained its peak brightness. The comet appears...

Venus and Jupiter on the Horizon
26.11.2019

What are those two bright objects on the horizon? Venus and Jupiter. The two brightest planets in the night sky passed very close together -- angularly -- just two days ago. In real space, they were...

Antares and Rho Ophiuchi
9.05.2004

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.

Spherical Planetary Nebula Abell 39
28.07.2005

Ghostly in appearance, Abell 39 is a remarkably simple, spherical nebula about five light-years across. Well within our own Milky Way galaxy, the cosmic sphere is roughly 7,000 light-years distant toward the constellation Hercules.

An Airglow Fan from Lake to Sky
3.02.2019

Why would the sky look like a giant fan? Airglow. The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured during 2015 next to Bryce Canyon in Utah, USA.

Dark Dust and Colorful Clouds near Antares
27.08.2019

Why is the sky near Antares and Rho Ophiuchi so dusty yet 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.

M31: The Andromeda Galaxy
19.01.2022

The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy. Even at some two and a half million light-years distant, this immense spiral galaxy -- spanning over 200,000 light years -- is visible, although as a faint, nebulous cloud in the constellation Andromeda.

Leaning Tower, Active Sun
1.04.2022

The natural filter of a hazy atmosphere offered this recognizable architecture and sunset view on March 27. Dark against the solar disk, large sunspots in solar active regions 2975 and 2976 are wedged between the Duomo of Pisa and its famous Leaning Tower.

APOD: 2023 November 12 Б Gibbous Moon beyond Swedish Mountain
12.11.2023

This is a gibbous Moon. More Earthlings are familiar with a full moon, when the entire face of Luna is lit by the Sun, and a crescent moon, when only a sliver of the Moon's face is lit.