Unusual Plumes Above Mars
23.02.2015

What is creating unusual plumes on Mars? No one is sure. Noted and confirmed by a global contingent of amateur astronomers on photos of the red planet in March 2012, possibly similar plumes have now been found on archived images as far back as 1997.

Unusual Spiral Galaxy M66 from Hubble
13.04.2010

Why isn't spiral galaxy M66 symmetric? Usually density waves of gas, dust, and newly formed stars circle a spiral galaxy's center and create a nearly symmetric galaxy. The differences between...

Unusual Spires Found on Comet Wild 2
22.06.2004

How did unusual spires form on comet Wild 2? Close inspection of images taken of Comet Wild 2 by the passing Stardust spacecraft in January show numerous strange pinnacles as long as 100 meters long jutting off the surface. The pinnacles were unexpected - close-ups of other comets and asteroids show no such features.

Unusual Gas Filaments Surround Galaxy NGC 1275
25.07.2005

How were the unusual gas filaments surrounding galaxy NGC 1275 created? No one is sure. Galaxy NGC 1275 is the central dominant galaxy of the Perseus Cluster of Galaxies, a cluster with many member galaxies visible in the above image. In visible light, NGC 1275 appears to show a spectacular collision between two distinct galaxies.

Unusual Rocks in Death Valley
10.04.2002

How did those big rocks end up on that strange terrain? One of the more unusual places here on Earth occurs inside Death Valley, California, USA. There a dried lakebed named Racetrack Playa exists that is almost perfectly flat, with the odd exception of some very large stones, one of which is pictured above.

An Unusual Hole in Mars
12.06.2017

What created this unusual hole in Mars? Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon-dioxide ice. The most unusual hole is on the upper right, spans about 100-meters, and seems to punch through to a lower level.

An Unusually Smooth Surface on Saturns Telesto
22.02.2006

Why is Saturn's small moon Telesto so smooth? Possibly Telesto is covered with a type of granular icy material similar to that suspected of covering Pandora, another of Saturn's small moon's. If so, Telesto might be more like a pile of rubble than a solid body.

APOD: 2025 April 13 Б An Unusual Hole in Mars
13.04.2025

What created this unusual hole in Mars? Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon dioxide ice.

Unusual Rocks near Pahrump Hills on Mars
29.09.2014

How did these Martian rocks form? As the robotic Curiosity rover has approached Pahrump Hills on Mars, it has seen an interesting and textured landscape dotted by some unusual rocks. The featured image shows a curiously round rock spanning about two centimeters across.

Unusual Plates on Mars
28.02.2005

What are those unusual plates on Mars? A leading current interpretation holds that they are blocks of ice floating on a recently frozen sea covered by dust. The unusual plates were photographed recently by the European Space Agency's Mars Express spacecraft currently orbiting Mars.