Time Zone Physics Tool
Earth rotates 15 degrees per hour, which is why time zones exist. Drag the time slider to move the sun, click any location to see its solar time, and explore why noon is different everywhere.
Jump to City
Major Cities - Local Solar Time
| City | Solar Time | Status | Std TZ |
|---|---|---|---|
| New York | 17:49 | Day | EST (UTC-5) |
| London | 22:45 | Night | GMT (UTC+0) |
| Paris | 22:55 | Night | CET (UTC+1) |
| Dubai | 02:27 | Night | GST (UTC+4) |
| Mumbai | 03:37 | Night | IST (UTC+5:30) |
| Tokyo | 08:04 | Day | JST (UTC+9) |
| Sydney | 08:50 | Day | AEDT (UTC+11) |
| Los Angeles | 14:53 | Day | PST (UTC-8) |
The Physics of Time Zones
15 Degrees per Hour
Earth rotates 360 degrees every 24 hours, which is exactly 15 degrees per hour. Every 15 degrees of longitude represents one hour of solar time difference. The theoretical time zone width is exactly 15 degrees.
Solar vs Standard Time
Solar noon (when the sun is highest) varies continuously with longitude. Standard time zones are political approximations that keep large regions on the same clock, so solar noon can differ from 12:00 by up to an hour or more.
Rotation Speed
The equator moves at about 1670 km/h due to Earth's rotation. This speed decreases with latitude as the circumference gets smaller. At the poles, the rotation speed is essentially zero.
