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It's amazing given the lifespan of celestial entities that we can witness such significant change in such seemingly human time scales (2 hours).

The milky way galaxy is estimated to be ~13.7B years old. The black hole was brighter for a 2 hours. That event, as a percentage of the milky way's age represents: 0.00000000000001666500016665%.

As a comparison of what that represents as a unit of time in an average human lifespan (79 years) it equals:

0.00000069197080291971 seconds. 0.00069197080291971 milliseconds. 0.69197080291971 microseconds.

I think a better comparison is to the size of the region in which this event occurred. For the event to appear to last only 2 hours to us, it can't have occurred in a region more than 2 light hours across. That's only 14 astronomical units, less than the diameter of the orbit of Saturn. There are stars bigger than that.

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