Astronomical Events¶
Each daily show must include triggers to turn the bridge lights on at sunset and release the show at midnight. The midnight stop is in keeping with guidance from Lights Out Pittsburgh to protect migratory birds; previously the bridge would continue all night until sunrise.
The sunset time is calculated using the current date and time based on the latitude and longitude of the bridge. The computed sunset time used by the astronomical trigger occurs at the start of ‘civil twilight’ when the sky itself is still relatively bright. The bridge lights are much more visible starting around ‘nautical twilight’.
The show start times can vary considerably throughout the year, especially considering the shift to Daylight Saving Time. In practice, students and staff who leave campus after ‘business hours’ typically only see the bridge lighting during mid-winter.
A usable reference for estimating the sunset time is https://www.timeanddate.com/sun/usa/pittsburgh
Date |
Sunset (show start) |
Nautical Twilight (sky dark) |
Notes |
|---|---|---|---|
Jan 18, 2022 |
5:21PM (EST) |
5:51PM (EST) |
start of Spring semester |
Mar 12, 2022 |
6:23PM (EST) |
6:50PM (EST) |
last day before Daylight Saving Time |
Mar 17, 2022 |
7:28PM (EDT) |
7:56PM (EDT |
first day of class |
Apr 28, 2022 |
8:12PM (EDT) |
8:41PM (EDT) |
final class show |
May 15, 2022 |
8:29PM (EDT) |
9:00PM (EDT) |
Commencement |
Jun 21, 2022 |
8:53PM (EDT) |
9:27PM (EDT) |
Summer solstice |
Aug 29, 2022 |
7:56PM (EDT) |
8:24PM (EDT) |
first day of Fall semester |
Dec 9, 2022 |
4:53PM (EST) |
5:23PM (EST) |
last day of Fall semester |
Dec 21, 2022 |
4:56PM (EST) |
5:27PM (EST) |
Winter solstice |