In the Spring/Summer:
- Dawn at 5:00 AM
- Sunrise at 6:00 AM
- Early Morning at 7:00 AM
- Day fron 8:00 AM to 5:59 PM
- Dusk at 6:00 PM
- Sunset at 7:00 PM
- Twilight at 8:00 PM
- Night at 9:00 PM to 4:59 AM
The fall sky backgrounds are one hour earlier on every time zone (such as Night beginning at 8:00 PM). The winter ones are two hours earlier (such as Sunset at 5:00 PM).
And the sky backgrounds when you're browsing as a guest always follow EST (GMT-5). During standard time, it's synchronized with the East Coast. During Daylight Time, it's synchronized with the Central Time regions (such as Texas). Regardless of DST time changes and time zones, it's always synchronized with your time zone if you're logged in.