Noctilucent Clouds Over Edmonton
20.07.2011

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.

An Unusual Globule in IC 1396
14.04.2014

Is there a monster in IC 1396? Known to some as the Elephant's Trunk Nebula, parts of gas and dust clouds of this star formation region may appear to take on foreboding forms, some nearly human. The only real monster here, however, is a bright young star too far from Earth to hurt us.

APOD: 2025 September 20 Б Gibbous vs Crescent
20.09.2025

Early risers around planet Earth have enjoyed a shining crescent Moon near brilliant Venus, close to the eastern horizon in recent morning twilight skies. And yesterday, on September 19, skygazers watching from some locations...

Medieval Astronomy from Melk Abbey
17.04.2009

Discovered by accident, this manuscript page provides graphical insight to astronomy in medieval times, before the Renaissance and the influence of Nicolaus Copernicus, Tycho de Brahe, Johannes Kepler, and Galileo. The intriguing page...

Sunshine, Earthshine
19.03.2015

Today's date marks an Equinox and a New Moon. Remarkably, while the exact timing of both geocentric events occur within a span of only 13 hours, the moon also reaches its new phase only 14 hours after perigee, the closest point in its orbit.

The Belt of Venus over the Valley of the Moon
23.07.2006

Although you've surely seen it, you might not have noticed it. During a cloudless twilight, just before sunrise or after sunset, part of the atmosphere above the horizon appears slightly off-color, slightly pink.

Noctilucent Clouds Over Sweden
28.10.2007

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.

A Triangular Shadow of a Large Volcano
5.07.2011

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.

A Triangular Shadow of a Large Volcano
9.06.2019

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.

APOD: 2025 January 15 Б Wolf Moon Engulfs Mars
15.01.2025

Does the Moon ever engulf Mars? Yes, but only in the sense that it moves in front, which happens on rare occasions. This happened just yesterday, though, as seen from some locations in North America and western Africa.