JSCalc

The twilight isn’t always a set period. It varies with tilt of the earth and your latitude. Dawn also isn’t a one-point event in most … Read More

To find out precisely at what time sun will rise (or set), there’s an online calculator that takes the day of the year, your latitude … Read More

Where’s the Sun? That’s not a question for “looking up” as much as it is a precise geometric factor in photography, architecture, and solar energy. … Read More

A light bulb is a constant source of light. A light switch isn’t. The sun is a moving light source that arcs around our sky … Read More

It’s a number that measures rotation of the Crab Pulsar, which spins at such high speeds, 30 times per second, that a bike wheel would … Read More

Midnight strikes on your clock, the sun sinks below the horizon and you think that’s it for the day. Sleep. Meetings. Schedule. That’s how we … Read More

Amateur astronomers are all familiar with the instant of terror. You’re standing out in the cold, peering through telescope tube up at a starry sky, … Read More

The Earth’s rotation with respect to the distant stars, not the sun, are called sidereal time. It keep track of how sky moves over your … Read More