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 feature extensively in Avatar history and events. This knowledge is vital, as astronomical occurrences can directly affect bending power.

Spirits and people in the Avatar World maintain repositories of this information in various locations of the Avatar 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 of Avatar. It takes up the entire universe. Aang went to outer space once to control the Avatar State.

Eclipses
People know the cause of eclipses, and they can be predicted through a Planetary Calendar Room. An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another.

Lunar Eclipse


Waterbending draws its power from the Moon. Though the Moon Spirit's mortal form is known to influence Waterbending, 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 moon. A solar eclipse affects Firebending by blocking the sun's heat and light, both of which Firebenders use to control their bending. As the moon's gravity would still affect the Earth during a lunar eclipse, (i.e. its ability to "push and pull" the tides) it is possible that a lunar eclipse would not affect the ability to Waterbend.

Solar Eclipse


Solar eclipses, known as the Day of Black Sun in the World of Avatar, refers to a day in history when a solar eclipse occurs when the sun is entirely blocked out by the moon, rendering Firebenders powerless. There have been two known days of black sun in history. 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. 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 Sun to reach its northernmost or southernmost extreme in the sky during the day. Solstices can be predicted too. During the Solstice, the Spirit World and the natural world are at their closest, and 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. In the Avatar World, as the solstice approaches, the natural world and the spirit world grow closer together until the line between the two is blurred. During the solstices the 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. In the Avatar World, the Winter Solstice, and the Summer Solstice are the only times that the Spirit World and the mortal world come close together enough to interact freely with each other for good amounts of time. This event is experienced when Aang meditates 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 towards 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 and, when close enough to the Sun, and in Sozin's Comet's case at the edge of Earth's atmosphere, exhibits a visible coma (atmosphere) or a tail — both primarily from the effects of solar radiation upon the comet's nucleus. The coming of a comet can be predicted.

Sozin's Comet


Sozin's Comet is a comet that seems to pass close to the world of the Avatar every hundred or so years. The comet passes close enough that Firebenders are able to draw power from it as they normally do the sun, greatly increasing 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 wouldn't 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, which is why it is called Sozin's Comet.

Meteorites


A Meteorite is a natural object originating in outer space that survives an impact with the Earth's surface. Sokka chose a meteorite as the material to make his sword.

Lunar Calendar
A Lunar Calendar is a calendar that is based on cycles of the moon phase. It is used in the World of Avatar.

Astronomical Objects
People in the World of Avatar have a number of important astronomical objects.

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, presumably allowing those who use it to find true north when in the Northern Hemisphere of the World of Avatar.

Eclipse Glasses
Eclipse Glasses are a gadget invented by the Mechanist. When the invasion force invaded the Fire Nation 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 your 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 make an invasion at the Fire Nation.

Celestial Calendar
Located in center of the courtyard at the Sun Warrior city 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 was the only structure on the island. The temple was built on the island so that it aligned with the solstices and equinoxes as a calendar itself, and housed the Fire Sages.