Project Skygaze

🔭 Project Skygaze

A real night sky for Minecraft

The stars, planets, Moon and deep-sky objects come from real astronomical catalogues and move the way they actually do. You can look at them with your eyes, binoculars, small telescopes or a big observatory telescope.

I started this because the vanilla night sky always felt empty to me, yet I was fascinated by the star night sky and view of Milky Way across it all. The goal was a sky you can actually learn from: if you find e.g. Vega in Skygaze, you can walk outside and find Vega in the real sky in the same spot.

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⚠️ Version 1.5

A big update: weather, satellites, aurora, meteor showers, planets up close, and a new Professional optics mode where you run the telescope yourself. Some numbers will still be off and some things will break, especially with shaders that draw their own sky.

Please back up your worlds before trying it. If you find a bug, report it in the issues or the comments, ideally with a screenshot and your settings. That helps a lot.

It has been tested mostly in singleplayer. Dedicated servers are supported (the server's time settings now reach every player), but they have had less testing.

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✨ Features

🌌 The sky itself

✦ Real stars from the Hipparcos catalogue, from the brightest down to about magnitude 8, with their real colours

✦ About 4,500 named stars, with proper names and Bayer/Flamsteed designations (Sheliak is β Lyr, and so on)

✦ The Milky Way, which fades out as light pollution gets worse

✦ Telescope fields full of stars: through a telescope the faint stars, down to about magnitude 17, come in the numbers the real sky has, denser along the Milky Way. These are generated rather than taken from a catalogue, and the mod says so

✦ Constellation lines for all 88 IAU constellations

✦ Zodiacal light and the gegenschein, based on measured brightness maps. You need a really dark sky to see them

☁️ Weather and seeing

✦ Real cloud weather: clear nights about a third of the time, partly cloudy, mostly cloudy or overcast on others, changing from day to day. When it rains, the sky closes

✦ One field of clouds day and night: white by day, warm at sunset, moonlit at night. A cloud hides exactly the stars behind it, and the HUD tells you when the next gap will come ("a gap in ~25 s")

✦ Prefer Minecraft's own clouds? Switch in the settings, and the telescope gets blocked by those instead

✦ Seeing (how steady the air is) changes from night to night and through the night. It blurs stars, sets how much they twinkle and decides which double stars you can split

🪐 Solar System

✦ Planets on real orbits (JPL orbital elements). Day 0 of a world is the September equinox of 2026, and one game day is one real day

✦ That means the planets are where they really are and move at their real speed. Venus never strays far from the Sun, and Mars goes backwards around opposition

✦ Planets up close (press V on a planet): globes built from real spacecraft maps (Viking, Cassini, MESSENGER, Magellan), lit and turned as they really are at that moment, with weather: Mars's polar caps and dust storms, Jupiter's belts and its four large moons with their shadows, Saturn's rings and polar hexagon, Venus's clouds. Uranus and Neptune too, with their clouds and rings

✦ The Moon up close: real NASA LRO maps with real relief, so craters cast long shadows along the terminator, plus earthshine and libration. In the sky it follows the vanilla phases, with lunar and solar eclipses

✦ The Sun through a filter: white light with granulation and sunspots, or hydrogen-alpha with filaments and prominences. The spots follow the real solar cycle 25

✦ An instrument ladder in the close-up: see the same planet in binoculars, a 70 mm, 200 mm and 508 mm telescope, a 4 m telescope with adaptive optics, or Hubble. Each shows only the detail its aperture and tonight's seeing allow

🛰️ Things that move

✦ About 2,500 satellites: the ISS, Tiangong, Hubble, old rocket stages, Starlink and more, on orbits with their real inclinations and heights. They shine while you stand in the dark and fade as they enter the Earth's shadow, often in mid-sky. The notebook lists the next passes of the ISS, Tiangong and Hubble. (The bright passes are moved into twilight so a short game night still gets them, and the mod says so)

✦ Aurora: curtains 100 to 350 km up, drawn in true perspective, in the green, red and violet of real oxygen and nitrogen light, with substorms and pulsating patches. Driven by a simulated geomagnetic index (Kp) with storms and a three-day forecast. Faint aurora looks grey to the eye; a long exposure shows its colours

✦ 38 real meteor showers from the International Meteor Organization calendar, on their real dates and radiants, at their real speeds and rates. Hold a meteor watch like IMO observers do and get your own ZHR

✦ Star trails: a long-exposure photo of the turning sky, from 30 minutes to 8 hours

🌀 Deep sky

✦ About 8,800 real objects from the OpenNGC catalogue: galaxies, nebulae, star clusters, planetary nebulae

✦ Real sizes, shapes and orientations, with sharper galaxies and clusters at high power

✦ Whether you can see an object depends on its surface brightness, your instrument and your sky, not just its magnitude. A big faint galaxy is harder to spot than a small bright one, just like in real life

👁️ Observing

✦ Dark adaptation: your eyes adapt over time like real ones (cones first, then rods). Torches and bright light ruin it

✦ Your age (in the settings) sets the size of your dark-adapted pupil, about 7 mm at twenty and 5.5 mm at seventy. Hold B for averted vision, which shows a little fainter once your eyes are adapted

✦ Light pollution on the Bortle scale (1 to 9), calculated from the actual light sources around you. A village gets you around class 4; to reach class 8 or 9 you need a lot of lamps

✦ Red-light mode tints the mod's screens red so reading them doesn't cost your night vision

✦ Star hopping: pick a target in the planetarium and the mod plans a route to it from a bright star, step by step, the way people find faint objects with a finder

✦ Observing sessions (press R): sketch the field and get it checked against the real sky, estimate variable stars like AAVSO observers do, measure double stars with a micrometer

✦ Double stars and variable stars (Algol, Delta Cephei, Mira, Betelgeuse)

🔬 Close-up mode

Press V for a separate view, clearly labelled as a scientific visualization. It shows what an object would look like up close:

✦ stars

✦ pulsars that spin and flicker

✦ the jet of the quasar 3C 273

✦ auroras on planets where they can happen

This is not what a telescope would show, and the mod tells you that. (The Moon, planets and Sun are different: their close-up views are built from real maps and data, see above.)

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🔭 Instruments

Instrument	What it's good for
Astronomer's Binoculars	Wide views, star clusters, the Milky Way
Field Telescope (70 mm refractor)	The Moon, planets, bright nebulae
Dobsonian Reflector (200 mm)	Galaxies down to about magnitude 14 under dark skies
Observatory Telescope (508 mm, block)	Right click with an empty hand to look through it
Research Telescope (4 m, block)	Adaptive optics, and a control room (press V) with a CCD camera, a spectrograph to measure redshifts and spectral classes, and a 3D fly-through of galaxies and nebulae
Radio Telescope (block)	Works by day and through cloud: find real pulsars in the noise, and measure the Milky Way's rotation curve at 21 cm

Every telescope has an 8×50 finder (press Z) to find your way before switching to the main eyepiece.

There are three optics modes in the settings:

✦ Simple: magnification steps and some tracking help

✦ Realistic: real focal lengths and eyepieces, exit pupil, seeing and the diffraction limit. Mounts without a motor don't track

✦ Professional (new): you run the telescope yourself (press J)

• Preparation: the mirror comes out warmer than the air and has to cool, or the image boils. A Newtonian gets knocked out of collimation when you carry it, so you fix it with three screws using a star test. You focus by hand, with a Bahtinov mask if you like. Dew forms on humid nights unless you use a dew shield and a heater
• Mount and pointing: the small refractor sits on a photo tripod, the Dobsonian has setting circles that tell you where to push it, and the observatory telescope has a German equatorial mount. You polar-align it with a polar scope, run the motor at star, Moon or Sun speed (with a real worm gear's periodic error), and align its GoTo on stars
• Eyepieces and filters: a case of eleven real eyepieces (Plössl, orthoscopic, 68°, 82°, 100°), 2× and 3× Barlow lenses, and UHC, [O III], H-beta, Moon, colour and solar filters. The image is turned the way a real telescope turns it: upside down in a Newtonian, mirror-reversed through a refractor's diagonal
• Astrophotography: a cooled mono or colour camera on the telescope. Real noise and dark current; stars trail if the mount doesn't track. Use an autoguider, dark and flat frames, and stacking that removes satellite trails. Save the result as a PNG

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🧰 Tools and blocks

Item	What it does
Star Chart	Opens the planetarium
Astronomical Notebook	Your observation journal, with a calendar of meteor showers, satellite passes and aurora
Brass Astrolabe	Measures latitude, longitude and sidereal time
Astronomical Sidereal Clock	Shows sidereal time and twilight stages, outputs redstone at night
Atmospheric & Seeing Monitor	Measures seeing, transparency and the Bortle class, outputs redstone
Astronomical Observer Station	Sets a fixed latitude for the area around it
Observation Site Charter	Records the latitude of a remote site to use at the station
Observatory Slit Shutter	An opening slit for your observatory dome
Star Chart Table	A table for looking up tonight's sky
Optical Solar Filter	Safe viewing of the Sun

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🏛️ Observatories in the world

✦ Six structures generate on their own: a great observatory with a copper dome, a radio telescope site, an amateur observatory with a cottage, a radome, a field station and a stargazers' camp. Each is furnished and meant to be lived in

✦ They pick flat ground instead of sinking into hills or rivers, and work with Terralith and Tectonic

✦ You can also build them from blueprints found in their chests

✦ They're built from decorative blocks, so you can't strip them for iron, gold or diamonds

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🌍 Time and location

✦ Your latitude depends on where you stand. Walking north or south changes it by 1 degree every 50 blocks. Walk far enough and the southern constellations come up

✦ By default the night is longer and the sky turns at its real speed, so you have time to observe. There are other time modes too, including plain vanilla time (see /skygaze)

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⌨️ Controls

Key	Action
O	Astronomical overlay (names, lines, info)
P	Planetarium
N	Notebook
R	Observing session / save an observation
V	Close-up mode (Moon, planets, Sun, stars) / research telescope control room
J	Telescope setup: preparation, mount, eyepieces, camera (Professional mode)
Z	Finder
B (hold)	Averted vision
M	Meteor watch (G shower meteor, H other meteor)
K	Star trails
Right click (hold)	Look through an instrument
Scroll	Change magnification / next eyepiece

You can change all of these in Controls.

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📦 Requirements

Minecraft	1.21.1
Mod loader	Fabric Loader 0.16 or newer
Required mods	Fabric API, owo-lib
Java	21
Optional	Mod Menu (for the settings screen)

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🐞 Known issues

✦ A crescent moon never shows up at night, because the mod ties the moon phases to the vanilla moon

✦ In the default time mode you see roughly the midnight sky all night, so you won't see the evening cone of zodiacal light, only its band and the gegenschein

✦ Shader packs that draw their own sky can hide Skygaze's sky. Set the shader's stars and sky to vanilla or off

✦ Some rates are sped up for play: meteors (an hour of observing in ten minutes), camera exposures (60× faster) and satellite passes (moved into twilight). The mod tells you where it does this

✦ Faint gradients can show slight colour banding

✦ Some info cards are a bit too narrow for long text

✦ Dedicated servers have had less testing than singleplayer

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📜 License

The mod's code is released under the MIT License. Feel free to use it in modpacks.

Some of the data bundled with the mod has its own license:

✦ The star catalogue and star names come from d3-celestial (BSD 3-Clause)

✦ The deep-sky catalogue comes from OpenNGC (CC BY-SA 4.0). The file the mod builds from it is shared under the same license

✦ The planet and Moon maps are NASA images in the public domain

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💫 Credits

Code and design: Project Skygaze

Star data

✦ ESA Hipparcos and Tycho-2 catalogues

✦ Yale Bright Star Catalogue (Hoffleit & Warren)

✦ IAU Working Group on Star Names

✦ d3-celestial by Olaf Frohn (BSD 3-Clause), for the star catalogue and the star names. Copyright (c) 2015, Olaf Frohn

✦ Washington Double Star Catalog (US Naval Observatory)

✦ General Catalogue of Variable Stars (Sternberg Astronomical Institute)

Deep sky

✦ OpenNGC by Mattia Verga and contributors (CC BY-SA 4.0)

Solar System and sky physics

✦ E. M. Standish, Keplerian Elements for Approximate Positions of the Major Planets (NASA JPL)

✦ Jean Meeus, Astronomical Algorithms (planet brightness, Jupiter's moons, the Sun's orientation)

✦ IAU rotation elements for the planets; P. G. J. Irwin et al. 2024 for the true colours of Uranus and Neptune

✦ Ch. Leinert et al. 1998, The 1997 reference of diffuse night sky brightness (zodiacal light)

✦ John E. Bortle, the Bortle Dark-Sky Scale

✦ International Meteor Organization, 2026 Meteor Shower Calendar (J. Rendtel, ed.)

✦ NOAA Space Weather Prediction Center, space weather scales (aurora activity)

✦ Published pulsar periods and dispersion measures (ATNF Pulsar Catalogue)

✦ B. Winn et al. 1994 (pupil size and age)

Images

✦ Milky Way: NASA Scientific Visualization Studio and ESA Gaia

✦ Moon: NASA LRO (LROC WAC colour map and LOLA heights), public domain

✦ Planets: NASA/JPL/USGS and partners: Viking (Mars), Cassini (Jupiter), MESSENGER (Mercury), Magellan (Venus), public domain

✦ Deep-sky sprites, close-up visuals and item textures were made for the mod

Platform

✦ Fabric Loader and Fabric API

✦ owo-lib by Wisp Forest

✦ Minecraft by Mojang Studios

This mod isn't affiliated with Mojang or Microsoft.