Instruct: Given a question, retrieve documents that can help answer the question.
Query: What is the source of power for the Green Lantern?
The character of Harold "Hal" Jordan was a second-generation test pilot, having followed in the footsteps of his father. He was given the power ring and battery (lantern) by a dying alien named Abin Sur, whose spaceship crashed on Earth. Abin Sur used his ring to seek out an individual who was "utterly honest and born without fear" to take his place as a member of the corps. At one point, when Hal Jordan was incapacitated, it was revealed that there were two individuals matching the specified criteria on Earth, the other being Guy Gardner, and the ring chose Jordan solely because of his proximity to Abin Sur. Gardner then became listed as Hal's "backup", even though he had a strong friendship with Barry Allen (The Flash). Gardner would fill in if Jordan was unavailable or otherwise incapacitated. Later, when Gardner was put into a coma, it turned out that by then there was a third human suitable for the task, John Stewart, who was designated as the Earth Sector's "backup" Lantern. Jordan, as Green Lantern, became a founding member of the Justice League of America and as of the mid-2000s is, along with John Stewart, one of the two active-duty Lanterns in Earth's sector of space.
Alan Scott's Green Lantern history originally began thousands of years ago when a mystical "green flame" meteor fell to Earth in ancient China. The voice of the flame prophesied that it would act three times: once to bring death (a lamp-maker named Luke Fairclough crafted the green metal of the meteor into a lamp; in fear and as punishment for what they thought sacrilege, the local villagers killed him, only to be destroyed by a sudden burst of the green flame), once to bring life (in modern times, the lamp came into the hands of a patient in a mental institution who fashioned the lamp into a modern lantern; the green flame restored him to sanity and gave him a new life), and once to bring power. By 1940, the lantern passed into the possession of Alan Scott, a young engineer. Following a railroad-bridge collapse of which he was the only survivor, the flame instructed Scott how to fashion a ring from its metal to give him fantastic powers as the superhero Green Lantern. He adopted a colorful costume and became a crime-fighter. Alan was a founding member of the Justice Society of America.
Before any other sentient beings existed in the universe, a race of beings calling themselves the Guardians of the Universe harnessed the power of the "green element", the greatest power in the universe, to create the Green Lantern battery. However, the battery was vulnerable to the color yellow, the one part of the light spectrum that could resist green. The Guardians hid the most concentrated source of yellow energy, the "yellow element", to prevent others from using it against them.
The Spectre bonded with Jordan in the hopes of freeing the former Green Lantern's soul from Parallax's taint, but was not strong enough to do so. In Green Lantern: Rebirth, Parallax began to assert control of the Parallax-Spectre-Jordan composite. Thanks to a supreme effort of will, Jordan was able to free himself from Parallax, rejoin his soul to his body and reclaim his power ring. The newly revived (and rejuvenated) Jordan awoke just in time to save Kyle Rayner and Green Arrow from Sinestro. After the Korugarian's defeat, Jordan was able to successfully lead his fellow Green Lanterns in battle against Parallax and with help from Guardians Sayd and Ganthet, imprisoned it within the personal power batteries of Earth's Lanterns, rendering the Green Lantern's rings free of the yellow impurity, provided they had the power of will to do so. Hal Jordan is once again a member of both the Justice League and the Green Lantern Corps, and along with John Stewart is one of the two Corps members assigned to Sector 2814, personally defeating Sinestro in the Sinestro Corps War. Jordan is designated as Green Lantern 2814.1.
After Sinestro went rogue, he was banished by the Guardians of the Universe to Qward in the antimatter universe. When he returned, he wielded a power ring which used yellow energy. After various encounters with Earth's Green Lantern, Hal Jordan, he was imprisoned within the Central Power Battery. There he was able to use his ring, which uses fear, as opposed to willpower, as a power source, to awaken Parallax from hibernation. From there, Parallax and Sinestro were able to influence the fall of Hal Jordan and instigate the fall of the Green Lantern Corps, leaving one last Green Lantern: Kyle Rayner.
The Green Lantern and Sinestro Corps under Soranik Natu form an alliance against the encroaching Dark Multiverse. Sinestro initially plans to cooperate but is met at the Source Wall by Lex Luthor, who invites Sinestro to Earth to join his Legion of Doom. Attracted by the promise of the "Invisible Emotional Spectrum", a source of power Sinestro became aware of in his youth just before joining the Green Lanterns, Sinestro abandons the Corps and travels to Earth. Reverting to his original Silver Age costume, and wielding the power of the Ultraviolet Corps rather than his Qwardian power ring, he successfully brainwashes half the planet and begins to bring the black sun Umbrax, source of the Invisible Spectrum, into the universe. After the plan is foiled, he remains an ally of Luthor.
In Green Lantern: The Lost Army, Guy Gardner is flung into the pre-Universe and is suddenly wearing both a Green and Red Power Ring. He manages to reunite with the Green Lantern Corps who were also trapped in the pre-Universe. During the last fight between the Green Lantern Corps and the various Lightsmiths, Guy's Red Power Ring is turned green.[35] In Green Lantern Corps: Edge of Oblivion, Guy is once again a fully fledged Green Lantern and helps the others to try and escape the impending death of the pre-Universe and back into their own.[36]
In addition to the standard powers of a Green Lantern power ring, Mogo can also alter his weather and surface conditions such as plant growth and gravity, and travel through space at faster-than-light speeds. Mogo has a form of sensory or extrasensory awareness of what is happening around and on it. However, his wellbeing is largely sustained by the constant supply of energy from a Green Lantern power battery. Without it, he eventually loses his strength and even falls into a seemingly comatose state. Mogo also telepathically guided the Green Lantern power rings to their bearers.
Ganthet encouraged Hal about harnessing the green light of pure willpower and the need of forging a new Green ring. He told Hal that the Green Lantern Corps has returned while they arrived at the base of Mogo and reunited it. While the Green Lantern Corps are reinstated, Ganthet and Sayd assign Hal and Kyle to find Saint Walker. After they brought Saint Walker back to the base of the Green Lantern Corps, they called Kyle to test his White Lantern power which they believed could bring the resurrection of the Blue Lantern Corps. When Saint Walker attempted a psionic link to Kyle's power, he was prevented from doing so by an unknown presence, which caused Kyle's White Lantern power to shut down, leading to his return as a Green Lantern.
While the Black Lantern Corps are powered by the black emptiness of space which represents death and therefore does not belong to the Emotional Spectrum, Black Hand is revealed to be the physical embodiment for these corps, in the same manner that Ion is the embodiment of willpower for the Green Lantern Corps. During the climax of "Blackest Night #8", Boston Brand tells the Corps' leaders that Black Hand is the "tether keeping Nekron within our world", and that as the avatar of Death he is also the only key to defeating the Black Lanterns permanently. Using the White Lantern power of Life, Hal Jordan commands ""William Hand of Earth - Live"", resurrecting Black Hand and removing him as the Black Lantern Corps' primary power source - which deals a crippling and eventually fatal blow to the Black Lanterns.
Doctor Polaris was later released from imprisonment during one of his "good" periods. He attempted to discover the source of Green Lantern's power by kidnapping his friend, Tom Kalmaku. Polaris learned Green Lantern's power battery was hidden at Ferris Aircraft and was able to put a magnetic barrier around it, which prevented Green Lantern from fully charging his ring. The hero tracked Kalmaku to Polaris' lair as his power ring ran out of energy. Polaris turned his weapon on the Green Lantern, apparently killing him. The emerald gladiator's body disappeared.
Originally, Green Lantern power rings typically held a limited charge. In earlier appearances, they required recharging every 24 hours, but more recently they possess a fixed amount of regular charge: that is, the charge is good for 24 hours of 'typical' use, but extended or extensive use will drain the charge more quickly. Green Lantern rings typically reserve a small portion of their power for a passive force field that protects its wielder from mortal harm. In dire emergencies, that energy reserve can be tapped at the expense of said protection. Power rings are usually recharged by a Green Lantern's personal battery, which looks like an old fashioned lantern made of dark green metal. The user typically points the ring towards the lantern, and usually gives the Green Lantern oath (below) while recharging the ring. These batteries are directly linked to the Central Power Battery on Oa and do not themselves need recharging.
In the 1993 Reign of the Supermen! storyline, the alien tyrant Mongul and his forces destroy Coast City (Jordan's former home), murdering all of its seven million inhabitants, while Jordan was off world. Angered, he flies into Engine City and attacks Mongul, eventually knocking him out with Steel's hammer.[13] This leads into the Emerald Twilight arc, which sees Jordan using his power ring to recreate Coast City as an instrument in the process of overcoming his grief, and talking to ring-created versions of his old girlfriend and parents. After his ring's power expires, a projection of a Guardian appears and admonishes him for using the ring for personal gain and summons him to Oa (the homeworld of the Guardians and the Green Lantern Corps) for disciplinary action.[14] Angered at what he sees as the Guardians' ungrateful and callous behavior, Jordan absorbs the energy from the Guardian's projection, goes insane and attacks Oa to seize the full power of the Central Power Battery (the source of power for all Green Lanterns), defeating and severely injuring several members of the Green Lantern Corps in the process, taking their power rings as his own and leaving them to die in space. He arrives on Oa and kills Kilowog, Sinestro, and all the Guardians except for Ganthet, who was protected by the other Guardians and survived without Jordan's knowledge.[15] He then renounces his life as Green Lantern, adopting the name Parallax after absorbing the Power Battery's vast powers.
In the late 1960s, Guy Gardner appeared as the second choice to replace Abin Sur as Green Lantern of sector 2814. Gardner was a candidate to receive Abin Sur's ring, but Jordan was closer. This placed him as the "backup" Green Lantern for Jordan. But early in his career as a Green Lantern, tragedy struck Gardner as a power battery blew up in his face, putting him in a coma for years. During the Crisis on Infinite Earths, the Guardians split into factions, one of which appointed a newly revived Gardner as their champion. As a result of his years in a coma, Guy was emotionally unstable, although he still mostly managed to fight valiantly. He has gone through many changes, including wielding Sinestro's yellow Guardian power ring, then gaining and losing Vuldarian powers, and readmission to the Corps during Green Lantern: Rebirth. He later became part of the Green Lantern Honor Guard, and oversees the training of new Green Lanterns. Gardner is designated as Green Lantern 2814.2 within the Corps.
When temporally displaced astronaut Colonel George Taylor goes missing on the alternate future Earth known as the "Planet of the Apes", Cornelius investigates and discovers an ancient ring, unlike anything his universe has ever seen. As its power echoes through the multiverse, the Guardians of the Universe must reveal to the Green Lantern Corps a secret they had hoped would remain buried. With the Green Lantern Corps, led by Hal Jordan, racing to get to the source of this power before Sinestro can get his hands on it, they will discover a secret concealed by the Guardians of the Universe on an alternate Earth trapped within a time loop-the setting of "Planet of the Apes".
In the lantern's story, Yalan Gur was once one of the greatest of the Green Lantern Corps, and, in the 10th century by Earth reckoning, the Guardians of the Universe chose to remove the customary weakness to the color yellow from his power ring. Without this limitation, however, he was corrupted by his power, and he came to Earth and enslaved the people of China. The Guardians of the Universe thwarted Yalan by adding a new weakness of wood to his ring, which allowed the club-wielding villagers to overwhelm their oppressor and mortally wound him. The dying Yalan Gur fled into Earth's upper atmosphere, where he merged with his lantern-shaped power battery as he died. His lantern then collided with a fragment of the Starheart and was merged with its magical essence, turning into the Green Flame that becomes the source of Alan Scott's power. The retcon involving the true reason behind the yellow impurity may mean these events have been retconned out of existence. 
In 2011, the Alan Scott character was revamped. His costume was redesigned and the source of his powers was changed to that of the mystical power of nature (referred to in the stories as "the Green").
In "Blackest Night" #3, Indigo-1 describes the premise behind the Black Lantern Corps' fictional relationship with the universe. She explains that the darkness in existence before the creation of the universe is what powers the Black Lanterns. Banished at the dawn of time by the white light of creation, its fighting back causes the white light to be fractured into the emotional spectrum. The events transpiring throughout the titles of "Blackest Night" are a result of the darkness, once again, fighting back against creation. She goes on to describe how a combination of all seven lights can restore the white light of creation and bring an end to the Black Lanterns. Throughout the "Blackest Night" event, each time a Black Lantern successfully removes the heart of one of their victims, a black, lantern-shaped speech balloon (used within "Green Lantern" and "Green Lantern Corps" to indicate that a power ring is speaking) depicts an ever-rising power level increasing in increments of 0.1 percent. In "Blackest Night" #4, the power meter is filled and Scar is able to transport the Black Central Power Battery to Coast City, and the true mastermind behind the Black Lanterns is able to step into the main DC Universe: Nekron.
After the conclusion of "Rage of the Red Lanterns", the Blue Lanterns and Jordan return to Odym. Jordan is unable to remove the blue power ring and finds that it was interfering with the use of his green power ring. Ganthet explains to Walker that they did say Jordan would lead the Blue Lanterns, but not as a Blue Lantern himself. As a Green Lantern, Jordan's will would have been capable of charging the entire Blue Lantern Corps. Sayd says that a new blue power ring will need to be made for Walker, as they are unable to remove his original one from Jordan. Ganthet tells Jordan that, in order to remove the ring, he must use it by finding something to hope for. Jordan leaves for Oa, and Ganthet tells Walker and Warth that they must continue to recruit others to their Corps. The Blue Lanterns have a new mission: to locate those who wield the indigo light, for hope and compassion must work together. On Oa, the Guardians find that they are unable to remove the blue power ring from Jordan as well. Distracted from the blue power ring by terrorist demands from Agent Orange, the Guardians launch an assault on Okaara in the Vega system. Jordan's blue power ring continues to cause problems as the Green Lanterns come to conflict with Larfleeze's Orange Lantern constructs. Becoming separated from the group however, Jordan's blue ring does attract Larfleeze's attention. Larfleeze lusts after the blue ring, but finds that his constructs are not immune to the blue light as they are from the green. The blue power ring refuses to be stolen by Larfleeze, claiming that hope is selfless. Larfleeze attempts to remove it by force, by severing Jordan's hand with an axe made from orange light. Though it is not initially clear to the reader, Larfleeze fails again. Sensing his hope of being relieved from the constant hunger he feels, the blue ring creates an illusion which fools him into believing he succeeded in stealing it; Jordan's hand is, in fact, intact, and the Blue ring is still on his finger. Jordan returns to battle Larfleeze with the Green Lantern Corps. During the battle, Jordan's blue power ring continues to repeatedly ask him what he hopes for. In frustration, Jordan says that he hopes that once the battle with Agent Orange is over that it will stop asking him what he hopes for. The blue ring registers this as a sincere hope, recharges all of the Green Lantern Corps' power rings, and allows Jordan to subdue Larfleeze. After Jordan gains control of his ring, it removes itself from him and leaves to find a new recipient in Sector 2828.
Chaselon is the Green Lantern of sector 1416; he first appeared in "Green Lantern" (vol. 2) #9 (November–December 1961) in a story written by John Broome and drawn by Gil Kane. Chaselon is a native of Barrio III, a planet inhabited by silicon based crystalline beings with thirteen senses. Barrio III was one of the planets that the mad Guardian Appa Ali Apsa "harvested" to create the planet Mosaic. Chaselon is one of the many Lanterns apparently killed when a maddened Hal Jordan attacks and destroys Oa. Although his shattered body is depicted floating in space, he later is found to be one of the many Lanterns captured by the Cyborg Superman to provide a power source for the new Manhunters. Chaselon and the captured Lanterns are eventually rescued by a revived Hal Jordan.
Alan Scott was the original Green Lantern character created in the Golden Age of comics. Alan created the mantle and identity of Green Lantern by himself and is not associated with the Green Lantern Corps, since his power ring was de-authorized by the Guardians even before his obtaining it. Prior to the Crisis, Scott's ring ran on magic, and not the Central Power Battery of Oa. In September 2011, The New 52 rebooted DC's continuity. In this new timeline, Alan Scott is the modern day Green Lantern for Earth 2.
In 2004, following the cancellation of "The Spectre" (vol. 4) featuring Hal Jordan, and a dropoff in sales of the "Green Lantern" comic, as well as the character's prominent appearance in the popular "", DC decided to return Hal Jordan as a Green Lantern. First, the "Green Lantern" monthly series was canceled with issue #181 and Geoff Johns was assigned to write "Green Lantern: Rebirth", which would pave the way for Jordan's return as a Green Lantern. The series would also answer lingering questions about Jordan's character, as well as reveal the decades-long mystery of why the Green Lantern power rings, the powerful weapons assigned to each Lantern that allow them to conjure virtually any form of matter or energy, were unable to affect anything yellow in color.
During the War of the Green Lanterns storyline, the Guardians had been discussing the various events occurring ranging from Hal Jordan's allegiance with the New Guardians, the revolt of the Alpha Lanterns and so on.[18] The group is then later confronted by Krona who reveals his plan to control emotions. As a result, he had the Butcher, Ophidian, Ion, Adara, Proselyte, and the Predator inhabit the six Guardians as hosts and placed Parallax back within the Green Central Power Battery to subjugate the Green Lantern Corps under his control.[19] The Guardians are freed from Krona's control emotions by Hal Jordan, who kills Krona using his ultimate power. The rings from the other corps return to their former wielders. However, the Guardians expel them from Oa. The Guardians believe Hal to be the most dangerous of the Green Lantern Corps. Therefore, the Guardians discharge him from the Corps.[20] Afterward, the Guardians of the Universe allow Sinestro to become a Green Lantern once more. However, the Green Lantern Corps learn from empathy Lantern Meadlux that the Guardians are afraid of Hal Jordan, fearing that what happened to Krona would eventually happen to them if Jordan was allowed to continue as a Green Lantern.[21] Later, when the Green Lantern Corps are in disagreement and attempt to kill Sinestro, the Corps break into the sciencells, but the Corps discover that the Guardians have in captivity Sinestro and are trying to remove Sinestro's green ring, but the ring will not be removed. Later, the Green Lantern Corps were in a meeting by the Guardians that they choose between discipline continuing the fight and that any intrusion will incite a mutiny. The other Green Lantern Corps are in agreement.[22]
Issue #3 of the miniseries "Flash and Green Lantern: The Brave and the Bold" (December 2000) has Flash, Kid Flash, and Green Lantern in pursuit of Mirror Master and Black Hand. The villains attempt to steal Flash's speed but Kid Flash loses his powers instead. Green Lantern creates a temporary power ring for Wally to use, dubbing him Kid Lantern. Wally's Lantern costume is palette swap of his Kid Flash costume, with black pants, green top/boots, white gloves, and a Green Lantern insignia in place of his lightning insignia.
As Hal accepts the offer to act as the leader of the Green Lantern Corps, all the corps started experiencing failure of their rings during a battle with Larfleeze. They then face an unexpected threat in the form of Relic, a resident of the universe that existed prior to this one, who seeks to destroy the various Corps in the belief that using the powers of the emotional spectrum drains an emotional 'reservoir' and hastens the death of the universe. Relic goes on to shatter the Blue Lantern power battery, new home world killing all Blue Lanterns except Saint Walker. Following this, Relic, wielding lantern draining technology, destroys Oa and the green lantern power battery. Relic is proved correct as it becomes clear that the universe is coming to an end due to lanterns using the power of the emotional spectrum so he heads off to the Source Wall to save reality. To help fight Relic, Hal recruits now Red Lantern Guy Gardner. After joining with the Green Lanterns to fight Relic, Hal promises to give the Red Lanterns a sector for them to watch over. Unwittingly, this sector becomes Sector 2814, where Earth resides, giving guardianship of Earth to the Red Lantern Corps. With Relic trapped in the Source War it is Kyle Rayner with the entities (except Parallax) who is able to use his White Lantern status to replenish the emotional reservoir beyond the Source Wall.