A Colorful Solar Corona over the Himalayas
11.01.2016

What are those colorful rings around the Sun? A corona visible only to Earth observers in the right place at the right time. Rings like this will sometimes appear when the Sun or Moon is seen through thin clouds.

Eclipse Street, Hong Kong
25.06.2020

On June 21 an annular solar eclipse came soon after the solstice and our fair planet's northernmost sunset for 2020. At maximum eclipse, the New Moon in silhouette created a ring of fire visible along a narrow path at most 85 kilometers wide.

A Solar Corona Ejection
8.11.1996

The Sun would not be a nice place to spend the summer. One reason, besides the extreme heat, is that explosions are common there. In the above picture, magnetic fields buckle releasing previously constrained hot material from the upper atmosphere of the Sun.

Mariner's Mercury
17.12.1996

Mercury, the closest planet to the Sun, remains the most mysterious of the Solar System's inner planets. Hiding in the Sun's glare it is a difficult target for Earth bound observers.

Detailed View of a Solar Eclipse Corona
16.03.2010

Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight.

Surprising Comet ISON
30.11.2013

After failing to appear for Sun staring spacecraft at perihelion, its harrowing closest approach to the Sun, sungrazing Comet ISON was presumed lost. But ISON surprised observers yesterday as material still traveling along the comet's trajectory became visible and even developed an extensive fan-shaped dust tail.

A Day in the Life of a Human Sundial
12.08.2017

Have you ever wanted to be a gnomon? Of course, a gnomon is the tall part of a sundial that casts a shadow. The gnomon's shadow moves as the Sun moves across the sky, indicating time by the shadow's position on the dial face.

Mars in the Loop
8.11.2018

This composite of images spaced some 5 to 9 days apart, from late April (bottom right) through November 5 (top left), traces the retrograde motion of ruddy-colored Mars through planet Earth's night sky.

Sunset Analemma
21.06.2019

Today, the solstice is at 15:54 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth's sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south.

APOD: 2004 August 27- The Sedna Scenario
27.08.2004

The discovery of Sedna (aka 2003 VB12), the most distant known object orbiting the Sun, presents a mystery. Pluto's orbit averages about 40 AU in radius, where an AU (Astronomical Unit) is the Earth-Sun distance.