Astronomy in the World of Avatar

People in the World of Avatar have limited knowledge about astronomy and the universe around them. This extends to knowledge of eclipses and solstices, which are featured extensively in history and events. This knowledge is vital, as astronomical occurrences can directly affect bending power.

Spirits and people in the Earth maintain repositories of this information in various locations of the world, though much of it has been lost with the burying of Wan Shi Tong's Library.

Outer space
Outer space is the term for the massive amount of empty space on the plane of existence surrounding the entire world. It takes up the entire universe. Avatars can go out to outer space when controlling the Avatar State.

Eclipses
An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another. People know the cause of these phenomena and they can be predicted through a planetary calendar room.

Lunar eclipse


Waterbending draws its power from the moon. Though the Moon Spirit's mortal form is known to influence the bending art, the effects of astronomical events are not clearly defined. During a lunar eclipse, the moon is merely hidden from view in the shadow of the Earth, with no interfering body in between, unlike a solar eclipse, where the sun is actually obscured by the satellite. A solar eclipse affects firebending by blocking the sun's heat and light, both of which firebenders use to control their bending.

Solar eclipse


Solar eclipses, known as the Day of Black Sun, refers to a day when the sun is entirely blocked out by the moon, rendering firebenders powerless.

A day of black sun was used for the Invasion of the Fire Nation. The invaders forced their way up the main route to the Capital City, and with the eclipse fast approaching, the firebenders were in full retreat. The invaders then put on their eclipse glasses for observing the eclipse safely, without unnecessarily damaging the eyes. Meanwhile, the Avatar and his friends encountered War Minister Qin in the caverns, and with him totally defenseless, he told them of the Fire Lord's whereabouts.

Solstices
A solstice is an astronomical event that occurs twice a year, when the tilt of the Earth's axis is most oriented toward or away from the sun, causing the star to reach its northernmost or southernmost extreme in the sky during the day. Solstices, as other astronomical phenomena, can be predicted. During the solstice, the Spirit World and the natural world are at their closest, while during the equinox they are at their farthest.

Winter solstice


The winter solstice is a natural phenomenon that occurs when the sun is at its greatest angular distance from the equator. It is also the shortest day of the year. The solstice approaches the natural world and the Spirit World grow closer together until the line between the two is blurred. During the solstices, spirits can exert incredible power in the natural world. This is also the ideal time for people with the ability to enter the Spirit World. Spirits can appear in the real world for a short time on the solstice, like Avatar Roku.

Summer solstice


The summer solstice is a natural phenomenon, occurring when the sun is at the closest angular distance to the equator. It is also the longest day of the year. The winter solstice and the summer solstice are the only times that the Spirit World and the natural world come close together enough to interact freely with each other for good amounts of time. This event is experienced when Aang meditated in order to communicate with Avatar Roku about the latter's past events experienced when alive, such as his friendship, friendly rivalry and eventual conflict with his friend and the eventual Fire Lord Sozin.

When Zuko and Aang went to the ancient Sun Warrior civilization and toward a chamber with a celestial calendar in front of it, Zuko interpreted this as having to wait for a solstice in order for the door to open.

Comets
A comet is a small solar system body that orbits the Sun. When close enough to the Sun at the edge of Earth's atmosphere, comets exhibit a visible coma or a tail. The coming of a comet can be also predicted as it is periodic.

Sozin's Comet


Sozin's Comet is a comet that seems to pass close to the Earth every hundred years. The comet passes close enough that firebenders are able to draw power from it as they normally do the Sun, greatly enhancing their powers. Fire Lord Ozai claimed it enhanced firebending by a hundred Suns. Sozin used the power of the comet to kill all the airbenders, so the Avatar would not be born. He passed all the rest of his life trying to find him unsuccessfully. Sozin was the first person to draw power from the comet to commit genocide, being this the reason for its name.

Meteorites


A meteorite is a natural object originating in outer space that survives an impact with the Earth's surface.

When crafting his sword after concluding his swordsmanship training under Piandao's tutelage, Sokka chose a meteorite as the material to make it.

Astronomical objects
There is a significant number of important objects related to astronomy.

Lunar calendar
A lunar calendar is a calendar that is based on cycles of the moon phase.

Star chart


The star chart is a map of the stars and constellations. The constellations shown on the star chart closely resemble the Northern constellations of Earth, with the equivalent of Earth's North Star, Polaris, centered on the chart, allowing those who use it to find true north when in the Northern Hemisphere.

Eclipse glasses
Eclipse glasses are a gadget invented by the mechanist. When the invasion force raided the Fire Nation Capital on the Day of Black Sun, they could observe the eclipse safely as a means of keeping track of their time. They used this glasses to protect theirs eyes, as staring into an eclipse can damage the retina.

Sunstone
A Sun Warrior treasure, the sunstone is kept hidden inside a room in the Sun Warriors' ancient city which is supposed to be unlockable only during a solstice.

Telescope


The telescope was an instrument used by Zuko in his ship to spot objects or people from afar.

Planetary calendar room
The planetary calendar room is in the Wan Shi Tong's library, in the Si Wong Desert. Aang and Sokka used the room to search information about the eclipse to plan the Invasion of the Fire Nation.

Celestial calendar
Located in center of the courtyard at the Sun Warrior city, the celestial calendar is a large orange gem that refracts slivers of light onto a calendar on the ground. This gem is part of a celestial locking system that protects a sacred room. The room can only be opened on specific days, like the summer solstice. The Fire Sages also had such a calendar in the sanctuary of their temple on Crescent Island. As such, Aang was able to go to the temple on the winter solstice to speak to Avatar Roku.

Crescent Island
Crescent Island is a volcanic island on the outskirts of the Fire Nation archipelago. The Fire Temple, the only structure on the island, was built there so that it aligned with the solstices and equinoxes as a calendar itself, and housed the Fire Sages.