SaturnMoons vs Sideris
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SaturnMoons
Explore Saturn's rings and moons with this interactive guide. Pinpoint the location of its largest moons and step through time to see their future positions. Discover fascinating facts and images of Saturn's unique lunar family.
- Locate Saturn's nine largest moons
- Pinch-zoomable interface
- Local time synchronization
- Time controls (seconds, hours, days, years)
- Customizable telescope view
- Encyclopedia of Saturn's moons
- Stunning images of moons
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Let SaturnMoons guide you to observing Saturn’s complex system of rings and moons. Sky & Telescope’s latest app helps you locate Saturn’s nine largest moons with a pinch-zoomable interface set to your local time, guiding you to Saturn’s largest moon, Titan, or helping you try your luck with the fainter moons. The time controls allow you to step through the seconds or hours, or speed through days or even years to see where the moons will be down the line. And you can flip the view to customize what you see through your telescope. Plus, our full encyclopedia section contains fascinating entries and stunning images of Saturn’s bizarre lunar family. Learn more about Saturn’s “death star” moon, Mimas, two-faced Iapetus, and the salty ocean frothing beneath Enceladus’s surface. Please note: this application is designed to work in landscape orientation only so that you may view Saturn, Saturn’s rings, and the lunar family at their best.
Sideris
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Sideris is a plate solver for astrophotography with simple gear: a camera, a lens or a telescope, and a star tracker without go-to functionality. You aim at a galaxy and take a test shot, but the camera's screen only shows stars. Is your target in the frame, or just outside it? Take a photo of the screen with your phone (or tablet), and Sideris tells you exactly where your camera is pointing. Your shot appears on the interactive sky map, next to the target you are aiming for, so you know which way to move. No go-to mount, no laptop and no internet needed at your dark site. HOW IT WORKS 1. Take a test shot with your camera. 2. Photograph the camera's screen with your phone, or import the photo itself. 3. Crop it, and Sideris solves it in seconds, right on your device. 4. See your photo on the sky map, and how far you are from your target. PLATE SOLVING, FULLY OFFLINE • Solving runs on your phone, so it works where there is no signal. • Most photos solve with nothing but the picture. If one struggles, add your sensor size, focal length or target to help it. • From camera lenses to telescopes of about 1,200 mm on a full-frame camera. • A solve that fails does not use up a free solve. FRAME YOUR SHOT Add your cameras and your lenses or telescopes, and the framing tool shows your exact field of view on the sky map. Turn the frame to match your camera and plan the composition before you shoot. MORE THAN 21,000 DEEP-SKY OBJECTS • Messier, Caldwell, Herschel 400, NGC and IC, plus Sharpless, Barnard and Lynds nebulae, planetary nebulae, supernova remnants, star clusters and galaxy groups. • Show the 500 best known, the 2,500 within reach of a camera lens, or all of them. • Search any object by name or number, filter by type, catalog, magnitude, size or altitude, and sort the list by what matters tonight. • Every object has an altitude curve for the night, and the 110 Messier objects have NASA and ESA photographs. AN INTERACTIVE SKY MAP • 364,000 stars, the planets, and the Moon in its real phase. • Point your phone at the sky and the map follows. Select an object, and arrows guide you to it. • Constellation lines, an equatorial or azimuthal grid, and the sky at any date and time. TOOLS FOR THE FIELD • Polar scope: a Polaris reticle for the polar alignment of your star tracker. • Night mode: turns on at sunset to protect your night vision, with an all-red option for the darkest sites. • Moon phase calendar: phase, illumination, moonrise and moonset for every night. • White screen: a dimmable panel for flat frames. • Location from the GPS, or chosen on an offline world map. LEARN IT ON REAL PHOTOS A guided tutorial walks you through two real solves on example photos, with an animation of the whole process. ONE PURCHASE, NO SUBSCRIPTION Your first 10 solves are free. After that, a single one-time purchase unlocks unlimited plate solving on all your devices. No subscription, no ads, no account. I built Sideris for my own nights under the stars, after spending too many hours trying to find my targets. I hope it can help you take beautiful photos as well. Clear skies!
Screenshots
Verdict
The clearest difference is price: Sideris at Free against SaturnMoons's $2.99. Sideris also leads on update cadence (every 2 weeks vs every 26 months). SaturnMoons's advantage is in-app purchases (none vs 1) and iOS requirement (8.0 vs 15.0). On ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Sideris is free to download; SaturnMoons costs $2.99 up front. Sideris sells 1 one-off in-app purchase. SaturnMoons asks for nothing beyond the download.
SaturnMoons ships an update every 26 months, Sideris every 2 weeks. The most recent releases landed on November 6, 2026 and October 31, 2026 respectively.
| Parameter | SaturnMoons | Sideris |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 40.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 26 months | Every 2 weeks — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 8.0 — better | 15.0 |
| Further details — not scored | ||
| Size | 36 MB | 137 MB |
| Age rating | 4+ | 4+ |
| Developer | Guidebook Inc | Loris BERT |
In-app purchases
SaturnMoons
No in-app purchases
Sideris
- Unlimited Plate Solving$9.99









