Museum officials told the Sun-Times that they believe the outage is heat related.
Commonwealth Edison confirmed the outage and are investigating.
In a press release, the museum cited an "internal power issue" and said power was lost in the original galleries of the building.
The release also indicated that the museum will be closed for the remainder of the day. The aquarium will reopen Friday morning.
Aquarium officials encourage the public to check their website, Facebook page, Twitter feed or call 312-939-2438 for updated information.
