Galle is a crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 on Mars

Mars

Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

. It is located on the eastern rim of the huge impact basin Argyre Planitia

Argyre Planitia

Argyre Planitia is a plain located in the Argyre impact basin in the southern highlands of Mars. Its name comes from a map produced by Giovanni Schiaparelli in 1877; it refers to Argyre, a mythical island of silver in Greek mythology....

. It is named after the astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 Johann Gottfried Galle

Johann Gottfried Galle

Johann Gottfried Galle was a German astronomer at the Berlin Observatory who, on 23 September 1846, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the planet Neptune, and know what he was looking at...

.

Galle is often known as the "happy face crater" because the illusion

Pareidolia

Pareidolia is a psychological phenomenon involving a vague and random stimulus being perceived as significant. Common examples include seeing images of animals or faces in clouds, the man in the moon or the Moon rabbit, and hearing hidden messages on records played in reverse...

 of a smiley

Smiley

A smiley, smiley face, or happy face, is a stylized representation of a smiling human face, commonly occurring in popular culture. It is commonly represented as a yellow circle with two black dots representing eyes and a black arc representing the mouth...

 is created by a curved mountain range in the southern part of the crater and two smaller mountain clusters further north. The formation was first photographed by Viking Orbiter 1

Viking program

The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...

.

As the smiley is a key motif in the comic book

Comic book

A comic book or comicbook is a magazine made up of comics, narrative artwork in the form of separate panels that represent individual scenes, often accompanied by dialog as well as including...

 Watchmen

Watchmen

Watchmen is a twelve-issue comic book limited series created by writer Alan Moore, artist Dave Gibbons, and colourist John Higgins. The series was published by DC Comics during 1986 and 1987, and has been subsequently reprinted in collected form...

by Alan Moore

Alan Moore

Alan Oswald Moore is an English writer primarily known for his work in comic books, a medium where he has produced a number of critically acclaimed and popular series, including Watchmen, V for Vendetta, and From Hell...

 and Dave Gibbons

Dave Gibbons

Dave Gibbons is an English comic book artist, writer and sometime letterer. He is best known for his collaborations with writer Alan Moore, which include the miniseries Watchmen and the Superman story "For the Man Who Has Everything"...

, the crater was used as a story location after the coincidence was noted by Gibbons.