When we see spiral galaxies, some are face-on, others are edge-on, but most are tipped at an angle. But which side is closest to us?
All throughout the Universe, spiral galaxies are extremely common.
Along with elliptical galaxies, most of the Universe’s stars reside inside them.
Most observed spirals appear neither edge-on nor face-on, but tipped: inclined at an angle.
Remarkably, just by a visual inspection, you can conclude — with confidence — which edge of the galaxy is closest.
Unlocking the answer requires putting just two pieces of key information together.