CRUX

Overview

Crux (the Southern Cross) is the smallest of all 88 constellations but one of the most iconic in the Southern Hemisphere. Featured on the flags of Australia, New Zealand, Brazil, Papua New Guinea, and Samoa. Its compact cross shape has made it a symbol of southern identity for centuries.

Acrux and Mimosa are hot blue-white stars while Gacrux is a red giant, creating a striking color contrast within the cross. Crux has been used for millennia to locate the South Celestial Pole for navigation. The Coalsack Nebula (a dark nebula) is visible to the naked eye as a conspicuous dark patch east of the cross. The Jewel Box cluster (NGC 4755) is also found here.

How to Find It

From the Southern Hemisphere, look south for four bright stars forming a compact cross. Acrux (α) marks the bottom, Gacrux (γ) the top, Mimosa (β) the left arm, and δ Cru the right arm. The cross is unmistakable once you know what to look for.

To find the South Celestial Pole, extend the long axis (Acrux to Gacrux) about 4.5 times its own length southward — the pole lies near that point. This technique guided navigators for centuries before compasses were available. From the Northern Hemisphere, Crux is only visible south of latitude 25°N.

Mythology and Culture

In antiquity, the stars of Crux were considered part of Centaurus, visible from Mediterranean latitudes due to Earth's axial precession. As precession carried them below the European horizon, the cross was "lost" until the Age of Exploration when Portuguese and Spanish navigators rediscovered it in the 15th and 16th centuries.

Indigenous Australians have observed these stars for tens of thousands of years. Aboriginal astronomical traditions often identify dark nebulae rather than star patterns — the Coalsack forms the head of the "Emu in the Sky," a dark constellation spanning much of the Milky Way. Inca astronomers in South America also used Crux as a key marker in their agricultural calendar.

The Coalsack itself, a dense dark nebula southeast of the cross, is one of the most prominent naked-eye dark nebulae in the sky — an inky void that stands out against the bright backdrop of the Milky Way. The nearby Jewel Box (NGC 4755) is a young open cluster with a colorful mix of blue and orange supergiants visible in binoculars.

Star Trivia

Acrux (α Cru) — About 321 light-years away. A hot blue-white star at magnitude 0.77, and actually a close double star (B0.5 IV + B1 V) separable with a small telescope. The 12th brightest star in the night sky.

Mimosa (β Cru) — About 280 light-years away. A blue giant at magnitude 1.25 and a subtle pulsating variable. Despite being the beta star it is the second brightest in the constellation. Its name "Mimosa" is thought to refer to the mimosa flower (its exact origin is uncertain); β Crucis is one of the Southern Cross stars depicted on several southern-hemisphere flags.

Gacrux (γ Cru) — About 88 light-years away. An M3.5 red giant at magnitude 1.59 — the only red giant in the cross and the closest of the four stars. Its warm orange-red color contrasts beautifully with the blue-white hues of the other three stars and is apparent to the naked eye.

δ Cru — About 345 light-years away. A B2 blue star at magnitude 2.79, the faintest of the four but still a conspicuous second-magnitude star.

In Gravity Weaver

Crux is the thirtieth and final constellation in the game, a 4-stage zone defined by its cross shape (vertical axis: Acrux to Gacrux; horizontal axis: δ Cru to Mimosa).

The signature combo is Strong BH + Slab Meteor + Nebula. As the capstone of all 30 constellations, the three hazards appear at maximum density.

Plant a Gravity Well near the cross's center as a multi-directional hub, arc widely around the Strong BH, Slingshot to accelerate through nebulae, and slip past slabs along their long edges — the culmination of everything you've learned. Conquer all 30 constellations to chase the title of CONSTELLATION MASTER.