Sundogs over the VLA
23.08.1999

What if you woke up one morning and saw more than one Sun in the sky? Most probably, you would be seeing sundogs, extra-images of the Sun created by falling ice-crystals in the Earth's atmosphere. As water freezes in the atmosphere, small, flat, six-sided, ice crystals might be formed.

Sand Dunes Thawing on Mars
2.03.2008

What are these strange shapes on Mars? Defrosting sand dunes. As spring now dawns on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured above, are beginning to thaw. The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas.

When Rainbows Smile
10.03.2022

Want to see a rainbow smile? Look near the zenith (straight up) when the sun is low in the sky and you might. This example of an ice halo known as a circumzenithal arc was captured above a palm tree top from Ragusa, Sicily on February 24.

Circles in the Sky
16.05.2008

Gazing skyward on a sunny day in May, photographer Jean-Marc Lecleire captured this engaging display of ice halos forming complete circles in the sky. Recorded with a fish-eye lens from a spot near the grand Château de Chambord in France, the picture looks straight up, spanning almost 180 degrees from horizon to horizon.

Crescent Europa
24.02.2002

Although the phase of this moon might appear familiar, the moon itself might not. In fact, this crescent shows part of Jupiter's moon Europa. The passing robot spacecraft Voyager 2 captured this image in 1979.

Unusual Plates on Mars
27.02.2005

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.

Moon Corona, Halo, and Arcs over Manitoba
23.02.2020

Yes, but could you get to work on time if the Moon looked like this? As the photographer was preparing to drive to work, refraction, reflection, and even diffraction of moonlight from millions of falling ice crystals turned the familiar icon of our Moon into a menagerie of other-worldly halos and arcs.

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.

Extraordinary Solar Halos
20.12.2018

Welcome to the December Solstice, the first day of winter in planet Earth's northern hemisphere and summer in the south. To celebrate, consider this extraordinary display of beautiful solar ice halos! More common than rainbows, simple ice halos can be easy to spot, especially if you can shade your eyes from direct sunlight.

A Sun Halo Beyond Stockholm
9.01.2011

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.