Ionian Nebula
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The Ionian nebula is approximately 13,000 light years distant from the algae planet.
In their search for the Eye of Jupiter's function and symbolism, Lieutenant Felix Gaeta discovers that a nova occurred in the Ionian system which was seen 4,000 years ago, around the time the 13th tribe left Kobol. The nova left behind a gas cloud, known to the Colonials as the Ionian nebula (Rapture).
As Gaius Baltar's trial starts, the Fleet has almost reached the nebula and hopes to find its next clue to the location of Earth (Crossroads, Part I).