A compass in the stars: where the name Pyxis comes from

Pyxis is a small, faint constellation of the southern sky, a mariner's compass named by Lacaille. Here is the sky behind the name, and why a cleared web looks like it.

Shravan GoswamiShravan GoswamiMakes the gamesShravan runs Chaosmos. He designs the games, plays every build on his phone, and decides what ships., 2 min read
Pyxis level 152 cleared and drawn in the game's Constellation look: pale gold strands joining small eight-pointed stars on a dark night sky with a faint star chart grid

The game started life as Filament, a word for a fine thread. It ships as Pyxis, the name of a small constellation that most people have never looked for. Here is what the name means, where to find it, and why a puzzle about tangled webs took it.

The short answer

Pyxis is a constellation of the southern sky, and its name means a mariner’s compass. The word is Greek and Latin for a small box, and in full, Pyxis Nautica, it means the mariner’s compass. It is one of the 88 constellations astronomers use today, and it ranks 65th of them by area.

Who named it

Nicolas-Louis de Lacaille, a French astronomer, spent two years at the Cape of Good Hope in the early 1750s and catalogued almost 10,000 southern stars. He filled the gaps between the old constellations with new ones, most of them named after instruments of science and the arts. He first described this one in 1752 as la Boussole, the marine compass, and later gave it a Latin name.

Its stars had been seen long before, though. The ancient Greeks read them as the mast of Argo Navis, the great ship of Jason and the Argonauts. In 1844 John Herschel tried to put the mast back and rename it Malus, but Benjamin Gould restored Lacaille’s name, and Pyxis is what it is called today.

What it looks like

Pyxis is small and faint. Its brightest star, Alpha Pyxidis, is a blue-white giant of magnitude 3.68. Alpha, Beta and Gamma Pyxidis run in a rough line from south to north, a short needle that suits a compass.

The whole constellation rises for anyone south of 52 degrees north, which takes in all of India, and it is best seen in the evening in February and March.

Pyxis on a star chart beside Pyxis level 152 cleared in the Constellation look

Why a puzzle about webs

A level of Pyxis is a web of knots joined by straight strands, and you clear it by pulling knots until no strand crosses another. What is left is a few points joined by straight lines, with nothing crossing. That is exactly how a constellation is drawn on a star chart.

So when the game needed a new name, the sky was the obvious place to look. Pyxis is short and easy to say, and the stars it names already look like a cleared web. The game even has a Constellation look in its Web pack, which draws every knot as a small star.

A little compass in every web

There is no compass in the game, but every web does have a north to find. Each one is built from a solved layout, so a way out exists from the start, and the hint always points along a route that clears it. If you want to see the shape of the game before you play it, the rules are in Pull a knot, let it go, and the game itself is on its page.

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