Astrolabe

set date, time & latitude — read the sky

A real instrument, not a picture of one. The plate is cut for your latitude (its almucantars are exact stereographic circles); the rete — the openwork star map and ecliptic — turns over it with sidereal time. Set the dials and read where the Sun and stars stand.

Latitude 40°N

Day of year —

Time (local) 22:00

Longitude 0°

Spin — watch the sky turn

Presets — set it for me

Skin

Drag the disc to spin the rete (it sets the time). The bright day-circles are the tropics & equator; the tilted ring is the ecliptic carrying the Sun. Stars above the heavy horizon circle are visible now.