That is the skinniest Superman I've ever seen!
The Story: "Peril of the Paired Planets" by Denny O'Neil, Dick Dillin, and Joe Giella. Both Superman and Batman are felled by some mysterious affliction! Hawkman calls Green Lantern, Green Arrow, and Black Canary off leave for help, but the answer to their problems lies on...Earth-2!
Meanwhile, on Earth-2, Red Tornado runs into a spaceship(how do Reddy's powers work in airless space, again?), whose alien passengers knock him out with a laser. They talk of a plan to build a new planet, and to do that, you need energy--energy from two planets, so they rewire Reddy and send him into the void between Earth-1 and Earth-2 and use him as a sort of magnet, drawing the two worlds together, ever closer...
Then on Earth-2, Superman and Dr.Mid-Nite have the same thing happen to them that happened to the Earth-1 Superman and Batman, and when the Jay Garrick Flash falls, so does the Barry Allen one!
Thanks to Red Tornado, people start to see the other-Earth duplicates of themselves all over, causing panic! As the JSA tries to figure out what to do, our three hard-traveling heroes return to the satellite to help. Atom deduces there's some sort of mysterious connection between the two Earths, causing all this trouble.
Black Canary assumes its her, and comes to the conclusion that to solve all this...she must cease to exist! To be continued!
Roll Call: Superman, Batman, Flash, Green Lantern, Green Arrow Atom, Hawkman, Black Canary
Notable Moments: Ok, I understand Aquaman was off on his quest for Mera, but this is ridiculous. When Superman and Batman are knocked out, Hawkman makes a point to say how low-power the JLA is, so he calls GL, GA, and Canary off leave. At no point does he mention Aquaman. What the heck was going on here?