Sun Halo at Winter Solstice
14.01.2002

Sometimes it looks like the Sun is being viewed through a large lens. In the above case, however, there are actually millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.

Driving Toward a Sun Halo
13.06.2006

What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a large lens. In the above case, however, there are actually millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.

NGC 6164: Dragons Egg Nebula and Halo
26.12.2022

The star at the center created everything. Known as the Dragon's Egg, this star -- a rare, hot, luminous O-type star some 40 times as massive as the Sun -- created not only the complex nebula (NGC 6164) that immediately surrounds it, but also the encompassing blue halo.

Rosetta and Comet Outbound
28.11.2015

Not a bright comet, 67P/Churyumov-Gerasimenko now sweeps slowly through planet Earth's predawn skies near the line-up of planets along the ecliptic. Still, this composite of telescopic images follows the comet's progress as it moves away from the Sun beyond the orbit of Mars, from late September (left) through late November (far right).

Night on a Spooky Planet
30.10.2022

What spooky planet is this? Planet Earth of course, on a dark and stormy night in 2013 at Hverir, a geothermally active area along the volcanic landscape in northeastern Iceland. Triggered by solar activity, geomagnetic storms produced the auroral display in the starry night sky.

A Wolf Rayet Star Bubble
28.09.1997

What's a Wolf-Rayet star, and how did it create that spherical bubble and sweeping arc? A Wolf-Rayet star is a star that originated with a mass over 40 times that of our Sun.

A Wolf-Rayet Star Bubble
26.08.1996

What's a Wolf-Rayet star, and how did it create that spherical bubble and sweeping arc? A Wolf-Rayet star is a star that originated with a mass over 40 times that of our Sun.

Centaurus A: X-Rays from an Active Galaxy
5.07.2003

Its core hidden from optical view by a thick lane of dust, the giant elliptical galaxy Centaurus A was among the first objects observed by the orbiting Chandra X-ray Observatory. Astronomers were not disappointed, as Centaurus A's appearance in x-rays makes its classification as an active galaxy easy to appreciate.

Centaurus A: X Rays from an Active Galaxy
16.08.2001

Its core hidden from optical view by a thick lane of dust, the giant elliptical galaxy Centaurus A was among the first objects observed by the orbiting Chandra X-ray Observatory. Astronomers were not disappointed, as Centaurus A's appearance in x-rays makes its classification as an active galaxy easy to appreciate.

APOD: 2025 October 8 Б NGC 7380: The Wizard Nebula
8.10.2025

What powers are being wielded in the Wizard Nebula? Gravitation strong enough to form stars, and stellar winds and radiations powerful enough to create and dissolve towers of gas. Located only 8,000 light years away, the Wizard nebula, featured here, surrounds a developing open star cluster NGC 7380.