Due to the Earth's tilted axis and elliptical orbit, our clocks (which run at a constant speed) and the Sun (which appears to move at varying speeds) don't always match. This is why the earliest sunrise of the year doesn't actually fall on the summer solstice. Dawn vs. Sunrise

Starts when the sun is 18° below the horizon (the sky is no longer pitch black). How to Find Your Local Time

Many people confuse "dawn" with "sunrise," but they are distinct stages of morning light:

Because the Earth rotates 15° every hour, your east-west position determines your "true" sunrise time relative to UTC (Greenwich Mean Time).