THE NAMED SKY · CELESTIAL GEOMETRY
Constellations, asterisms, and fixed directions
See how fixed stars, camera direction, and connecting lines shape the constellations you recognise.
A constellation is an area of sky
The International Astronomical Union recognises 88 constellations as bounded regions covering the sky. Those boundaries identify which constellation contains a direction. They do not prescribe a single stick figure. Atlas makers and cultures can connect prominent stars differently while referring to the same official region.
An asterism is a familiar pattern that is not one of those 88 regions. The Big Dipper is an asterism inside Ursa Major. Polaris is a star in Ursa Minor. Solar Time makes both selectable because they are useful teaching targets, but describes the catalogue as constellations, asterisms, and stars.
Stars are directions, not wallpaper positions
A background texture creates depth, but a named star must keep a stable direction for its connecting lines to remain meaningful. Solar Time places catalogue stars on a celestial sphere. Moving the camera changes their projection onto the screen; it does not randomize the constellation.
Opening or warp may rotate the viewing frame, but rebuilding the solar-system presentation must not regenerate star coordinates. The apparent turn belongs to camera orientation and should settle into the saved or default view.
Projection changes the apparent drawing
A line figure on a sphere can look stretched, tilted, or mirrored after projection. Wide fields of view distort the edge more than the centre. Camera bank can turn a familiar W, cross, or dipper to an unexpected angle without any star moving.
The illustrated catalogue uses flat charts with north up and east left. The live app has a movable three-dimensional camera. Comparing the two requires matching orientation, not just the left and right edges.
Shared stars need visual context
Alpheratz lies in Andromeda and also forms a corner of the Great Square of Pegasus. The Big Dipper shares seven stars with the larger Ursa Major drawing. Polaris sits at the end of Ursa Minor's handle. Solar Time uses blue-white for the active line set and gold for other visible sets so shared data remain understandable.
The Andromeda Galaxy is a landmark
The Andromeda Galaxy lies in the direction of the Andromeda constellation near the chain beyond Mirach. Its separate decal is anchored to the celestial sphere and uses subdued edges so it reads as a distant object rather than an interface badge.
Try it in Solar Time
- Select Cassiopeia and rotate the camera. Watch the W become an M without changing its stars.
- Compare the Big Dipper and Ursa Major and identify the seven shared stars.
- Compare Pegasus with Andromeda and find Alpheratz in both line sets.
- Compare a static catalogue diagram with the live view before and after camera bank.
Sources and further reading
- International Astronomical Union — The Constellations
- NASA Science — Finding Polaris
- Solar Time Constellation Explorer