Lanterns Episode 7 Tests Green Lantern's Classic Yellow Weakness
In Lanterns' penultimate episode, Hal's ring powers the Hal-o-Gram in a yellow environment, reviving the Green Lanterns' historic yellow weakness.
In the penultimate episode of Lanterns season 1, John Stewart and the Hal-o-Gram leave Earth. The Hal-o-Gram's ring continues to function in a very yellow environment, a detail that nods to one of the Green Lantern Corps' oldest rules.
Historically, Green Lantern power rings did not work on anything yellow. The weakness dates back to Hal Jordan's first appearance, when he received his ring from Abin Sur in 1959's Showcase Comics #22. The original Green Lantern, Alan Scott, had a similar limitation: his ring failed against wood after his 1940 debut in All-American Comics #16.
How the Yellow Weakness Was Explained
Geoff Johns's 2002 series Green Lantern: Rebirth revealed that Parallax was a cosmic entity embodying fear. Imprisoned in the Central Power Battery, Parallax caused the rings' yellow weakness. Once Hal Jordan was freed from Parallax, Green Lantern rings worked on yellow.
For the past twenty years, yellow has not posed a problem to members of the Green Lantern Corps. The episode's yellow setting, as noted by Den of Geek, puts that history back in the spotlight.
Quick answers
Why didn't Green Lantern rings work on yellow?
The weakness was caused by Parallax, a cosmic entity embodying fear that was imprisoned in the Central Power Battery, as explained in Geoff Johns's 2002 series Green Lantern: Rebirth.
When did Green Lantern rings start working on yellow?
After Hal Jordan was freed from Parallax, the rings worked on yellow. For the past twenty years, yellow has not posed a problem to the Green Lantern Corps.
What was the original Green Lantern's weakness?
Alan Scott, who debuted in 1940's All-American Comics #16, had a ring that did not work on anything made of wood.