What to notice
Not every star moves by the same amount
If all the stars were equally distant, they would shift together. The fact that they do not is the clue that depth is hiding inside the familiar flat picture.
Explore
Parallax
Parallax is the apparent shift in position caused by a change in viewpoint. Move across the canvas to shift Earth’s position while the selected constellation stays centered — nearby stars slide more than distant ones, revealing the depth hiding inside a flat picture.
Status: Loading the parallax example…
Why it matters
Parallax is a measurement tool, not only a visual trick
In astronomy, parallax is one of the foundations of distance measurement. The same basic geometry that makes this page work also helps us map the nearby galaxy.
Try next
See it with free movement
The fly-through lets you navigate freely through the same stars. This page isolates the parallax effect so you can recognise it clearly before exploring at larger scale.