Skywatch

The sky is drawn in true horizontal coordinates for your chosen latitude and sidereal time, with stars rising and setting as time advances. A round of prompts asks you to identify a highlighted constellation or predict which one rises next. Answer quickly and accurately to score.

• The view rotates as sidereal time runs, just like a real sky
• Some prompts ask 'which constellation is this?', others 'which rises next?'
• Faster correct answers earn more

• Desktop: drag to pan across the sky; pick your answer from the prompt choices
• Phone & tablet: drag with a finger to pan and tap to answer

• Daily: the same sky and prompts for everyone
• Practice: endless new rounds

• Learn a few bright anchor constellations and star-hop from them
• Constellations near the eastern horizon are the ones about to rise
• Latitude changes which constellations ever clear the horizon, keep it in mind

Skywatch models the real geometry of the rotating night sky, building an understanding of how the stars and constellations move.

• Skills: astronomy, celestial motion, the night sky, Earth's rotation
• Best for: roughly grades 6–11 (ages 11–16)
• For parents & teachers: connects what we see in the sky to the geometry behind it.

Drawing the sky in true horizontal coordinates for a chosen latitude and sidereal time, with stars rising and setting as time advances, is a planetarium rather than a star chart.

Tying the view to latitude and sidereal time is the original rigour.

Both are necessary and both are usually hidden. Which stars are visible at all depends on latitude; when they are visible depends on sidereal time, which runs about four minutes a day faster than clock time — which is why the same star rises earlier each night.

Skywatch is an original astronomy game that models the real geometry of the rotating night sky. It's free to play in your browser, no sign-up required.

A free, original browser game on PlayPendium. No download, no install.