Your bravado amuses us, Superman! Indeed your interference will make the hunt more of a challenge for us... and for that, we thank you! As we are, in your terms, immortal-- we can wait until you are dead to proceed! 
Action Comics #550 is an issue of the series Action Comics (Volume 1) with a cover date of December, 1983.
Synopsis for "The Day The Earth Exploded"
An unnamed immortal alien race is wrecking the planet Earth while searching for five items placed on the planet Earth during its pangaea stage eons ago. It's up to Superman to stop the immortal aliens from destroying the Earth all in the name of a treasure hunt of galactic proportions.
Appearing in "The Day The Earth Exploded"
Featured Characters:
Supporting Characters:
- Lana Lang
- Josh Coyle
- Lewis Lang
- Jimmy Olsen
- Perry White (Mentioned only)
Antagonists:
- "The Exploder" (Unnamed) (Single appearance) (Origin)
- Three Members (Unnamed) (Single appearance)
- Six Members (Unnamed) (Flashback only) (Single appearance)
- Three Armor Truck Robbers (Unnamed) (Cameo)
Other Characters:
- Shark
- Lex Luthor (Mentioned only)
- Mark Olsen (Mentioned only)
- Metropolis Eagle (Mentioned only)
- The Flash (Barry Allen) (Mentioned only)
- Rao (Mentioned only)
- WGBS Cameraman (Unnamed) (Cameo) (Single appearance)
- NASA (Mentioned only)
- Batman (Mentioned only)
- Connie Hatch (Daily Planet's Puzzle Editor) (Single appearance)
Locations:
- Space
- Solar System (Mentioned only)
- Fifth Planet (Unnamed) (destroyed in the past; it was between Mars and Jupiter)
- Asteroid Belt
- Pluto (Mentioned only)
- Mars (Mentioned only)
- Jupiter (Mentioned only)
- Earth
- United States of America
- Metropolis
- Galaxy Communications Buildling
- WGBS Studios
- Storeroom
- Metropolis Museum
- Jimmy Olsen's Apartment (In ruins)
- Galaxy Communications Buildling
- California
- San Andreas Fault
- Metropolis
- Africa
- Pacific Ocean
- New Guinea
- Australia (Mentioned only)
- South America (Mentioned only)
- Asia
- Country (Unnamed)
- India (Mentioned only)
- Antarctica
- United States of America
- Solar System (Mentioned only)
Items:
- 5 Ancient Alien Disks (Flashback and main story) (Origin)
- Ancient Artifact (from Egypt found by Professor Lang)
- Ancient Artifact (from western South America found by Professor Olsen)
- Ancient Artifact (from California)
- Ancient Artifact (from Antartica)
- Ancient Artifact (from a jungle in Africa)
- Jimmy Olsen's Signal Watch
- Rubik's Cubes
- Oval Superman Symbol Cube (As merchandise only)
- Giant-sized Bronze Globe (Destroyed)
Vehicles:
- Alien's Spacecraft
- Ancient Alien Spacecraft (Flashback only)
Concepts:
- Pangaea (Flashback only)
See Also