Blue Flash
9.01.2002

Difficult to observe, the momentary green flash above the rising or setting sun has been documented as a phenomenon caused by the atmospheric bending or refraction of sunlight. Like a weak prism, the Earth's atmosphere breaks white sunlight into colors, bending red colors slightly and green and blue colors through increasingly larger angles.

Antarctic Analemma
23.09.2015

Does the Sun return to the same spot on the sky every day? No. A better and more visual answer to that question is an analemma, a composite image taken from the same spot at the same time over the course of a year.

A Ring of Fire Sunrise Solar Eclipse
15.06.2020

What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun.

APOD: 2023 September 24 Б A Ring of Fire Sunrise Solar Eclipse
24.09.2023

What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun.

Scintillating
28.04.2011

On June 4, 2010 Regulus, alpha star of the constellation Leo, and wandering planet Mars were at about the same apparent brightness, separated on the sky by 1.5 degrees. An ingenious and creative 10 second exposure from a swinging camera recorded these gyrating trails of the celestial pairing.

APOD: 2023 March 28 Б A Multiple Green Flash Sunset
28.03.2023

Yes, but can your green flash do this? A green flash at sunset is a rare event that many Sun watchers pride themselvesбon having seen.б Once thought to be a myth, a green flash is now understood to occur when the Earth's atmosphere acts like both a prism and a lens.

Moon Corona, Halo, and Arcs over Manitoba
24.02.2020

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.

The Light of Stars
8.05.2012

What's moving? Time lapse videos of the sky can be quite spectacular when they last long enough for stars, planets, aurora, and clouds to appear to move in just a few seconds. Pictured...

Boston Moonrise
24.03.2011

Last week's Full Moon was hard to miss. Rising on March 19, its exact full phase occurred within an hour of perigee, the closest point in the Moon's orbit to Earth.