The Journal · July 30, 2026

Terms of service

These terms govern your use of SkyChart. By creating an account or subscribing, you accept them.

Last updated: [[TO COMPLETE: date]]. Publisher: [[TO COMPLETE: legal entity, address, registration number]]. Contact: [[TO COMPLETE: email]].

What SkyChart is

SkyChart is a real-time sky map. It computes the position of the Sun, the Moon, the planets, some 41,600 stars, 1,735 deep-sky objects and a selection of artificial satellites for your date, time and location, and helps you find them in the actual sky. Some features require an account; some require a subscription.

Two warnings that matter

Never look at the Sun through binoculars, a telescope or any optical instrument without a filter designed for solar observation. It causes immediate and permanent blindness. SkyChart shows you where the Sun is; it cannot stop you pointing an instrument at it, and no feature of the app should be read as an invitation to do so.

Do not use SkyChart for navigation, aviation, marine or any safety-critical purpose. It is an observation aid for amateurs. Its compass depends on your phone's magnetometer, which drifts near metal and electrical interference, and its positions — while computed rather than approximated — carry stated tolerances. Watch where you are walking when you are looking up.

Your account

You are responsible for keeping your password to yourself and for what happens under your account. One account per person. Give us an email address that works: it is how we confirm your identity and how you recover access if you lose your password.

You may delete your account at any time from your account page. Deletion is immediate and cannot be undone. We may suspend an account that is used to attack the service, to abuse other users, or in breach of these terms — in which case we will tell you why.

Premium subscription

The subscription unlocks the alternative sky cultures and the other features marked as premium in the app. Prices and billing periods are shown on the subscription page before you pay; payment is handled by Stripe.

• Renewal is automatic at the end of each period, at the price in force when the period began.
• You can cancel whenever you like. Cancellation takes effect at the end of the period you have already paid for — you keep premium access until then, and are not charged again.
• We do not refund part of a period already started, except where the law requires it or where the service was unavailable through our fault.
• If a price changes, we will tell you before the renewal it applies to, with enough notice for you to cancel first.

Right of withdrawal

If you are a consumer in the European Union, you normally have fourteen days to withdraw from a distance contract. Because a subscription gives you immediate access to digital content, you are asked to confirm at checkout that you want performance to begin at once and that you understand this shortens or ends that right once the service has been fully performed. [[TO COMPLETE: have this clause reviewed by a lawyer against your final checkout flow — the wording must match what the customer actually confirms at payment.]]

Accuracy, and its limits

We compute rather than approximate, and we publish our tolerances on the credits page. Everything visible to the naked eye or through binoculars is positioned to the arcminute or better. Two exceptions we state openly: the light-pollution class is an estimate derived from satellite measurements rather than a reading taken where you stand, and the positions of Ceres and Vesta come from orbital elements that ignore planetary perturbations and drift slowly over the years. Satellite predictions depend on orbital data published by third parties and on manoeuvres we cannot know about in advance.

The service is provided as it is. We do not promise it will never be interrupted, nor that a predicted satellite pass will happen exactly as forecast.

What belongs to whom

The application, its interface, its editorial content and its illustrations are protected by copyright. You may not copy, resell or redistribute them without our written permission.

The astronomical data is a different matter, and an important one: much of it comes from open catalogues under licences that require attribution and, in several cases, that derivative works stay under the same licence. Those sources and their licences are listed in full on our data and credits page. If you plan to reuse any of that data, read the licence — ours does not replace it.

Liability

We are liable for damage caused by our own fault, on the terms the law provides. We are not liable for a missed observation, a cloudy night, a satellite that manoeuvred, or a decision you took on the basis of a prediction. Nothing in these terms limits your statutory rights as a consumer or our liability where the law does not allow it to be limited.

Changes to these terms

We may change these terms. If a change materially affects your rights, we will notify account holders by email before it takes effect, and if you subscribe you will have the opportunity to cancel before the change applies to you.

Law and jurisdiction

These terms are governed by [[TO COMPLETE: governing law]]. Disputes fall to the courts of [[TO COMPLETE: jurisdiction]], without prejudice to the rules that let a consumer bring a claim before the courts of their own country of residence. Before going to court, write to us — most things are settled by email.