Red Auroral Corona
15.01.2002

Few auroras show this level of detail. This unusual display of an auroral corona occurred on Earth three days after an unusual solar event -- the fifth most powerful explosion yet recorded on the Sun. An X14-class solar flare on April 15 sent a tremendous Coronal Mass Ejection (CME) into the Solar System.

Dusty Galaxy Centaurus A
28.08.1995

One of the most unusual galaxies known, Centaurus A, is pictured above. Cen A is marked by dramatic dust lanes that run across the galaxy's center. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light.

APOD: 2024 August 14 Б Meteors and Aurora over Germany
14.08.2024

This was an unusual night. For one thing, the night sky of August 11 and 12, earlier this week, occurred near the peak of the annual Perseid Meteor Shower. Therefore, meteors streaked across the dark night as small bits cast off from Comet Swift-Tuttle came crashing into the Earth's atmosphere.

An Unexpected Rocket Plume over San Francisco
11.11.2015

What is that unusual light in the sky? A common question, this particular light was not only bright but moving and expanding. It appeared just as the astrophotographer and his friend were photographing the Golden Gate Bridge in San Francisco, California against a more predictable night sky.

Aurora Over Clouds
2.04.2001

Aurorae usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact air molecules high in the Earth's atmosphere. An oxygen molecule, for example, will glow in a green light when reacquiring an electron lost during a collision with a solar particle.

Mysterious White Rock Fingers on Mars
7.04.2008

What caused this unusual white rock formation on Mars? Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate that this is not correct.

Nacreous Clouds over Sweden
10.01.2020

Vivid and lustrous, wafting iridescent waves of color filled this mountain and skyscape near Tanndalen, Sweden on January 3. Known as nacreous clouds or mother-of-pearl clouds, they are rare. This northern winter season they have been making unforgettable appearances at high latitudes, though.

Aurora in Red and Yellow
10.04.2000

The past week brought some spectacular aurora to northern skies. These aurorae were caused by a large interplanetary shock wave that exploded from the Sun on April 4. When the shock wave reached the Earth on April 6, the resulting aurora could be seen in clear skies as far south as North Carolina.

Noctilucent Clouds, Reflections, and Silhouettes
26.06.2019

Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above.

Venus and the Triply Ultraviolet Sun
20.08.2013

An unusual type of solar eclipse occurred last year. Usually it is the Earth's Moon that eclipses the Sun. Last June, most unusually, the planet Venus took a turn. Like a solar eclipse by the Moon, the phase of Venus became a continually thinner crescent as Venus became increasingly better aligned with the Sun.