For teachers

An astronomy site in English and Czech.

ObserveTheSky is free and has no ads. If you would like to support it:

What it is

ObserveTheSky is written for anybody who wants to know how a thing was worked out, and it shows the arithmetic, not just the conclusion. It has six parts, one for each button in its header: Space, a zoomable model of everything from a moon out to the galaxies; the Planetarium, which computes the real sky for your school’s location and any date; Sky, a page for every object; Explanations, showing how each distance was actually measured; Games, short ones that ask before they tell; and Guides, like this one.

Younger readers have their own site: AstroKids (astrokids.net) is the same sky for a child of about six upwards, alone or beside a grown-up — the model and the printables, short stories about going out to look, and no arithmetic in the way. Two sites, two readers, one database underneath.

For a classroom, the parts that matter: it loads with no account and no sign-in, it shows no advertising of any kind, it keeps no personal data and sets no cookies (it counts, anonymously, which parts are used, and sends nothing at all when it is offline), and it works with the network unplugged — download the folder once and it runs from the disk. The only links out to the open web are a short, checked list of space agency sites, the sister site astrokids.net, and one donation link (Ko-fi).

Fitting it to a lesson

The solar system — the eight planets, the two belts, and how much empty space lies between them
The Milky Way — why our own galaxy looks like a band and not a spiral
Galaxies — the shapes, and what each shape tells you
The universe — scale, the Big Bang, and what is unknown
Everything we can actually observe — sorted by what equipment it needs — useful for setting expectations
Every kind of object there is — a taxonomy table, generated from the database

The strongest part, for teaching

The explanation pages. School astronomy is usually a list of facts to accept; seven of these pages are measurements a child can partly repeat, each one standing on the one before. Eratosthenes with a stick. The Moon’s size from the curve of a shadow. Kepler’s ellipse with two pins and a loop of string. Every one of them ends in something to go and try.

How big is the Earth? — a stick, a shadow, and two towns — repeatable with a partner school
The size and distance of the Moon — the curve of a shadow, and a hole punched in card
How the solar system is arranged — two pins, a string, and a check against real orbital periods
The distance to the Sun — it deliberately fails first, which is the lesson
All the explanation pages — all 32 of them, the seven measurements among them

Printables

Observation logs, colouring sheets and cut-out models are on AstroKids. The observation sheets are designed to be filled in outdoors and kept.

If you take a class outside

The Planetarium will plan a session for your school’s coordinates and a chosen date: what is above the horizon, in what order it sets, and when it is actually dark enough. Two objects is a good night for a group.

🌙 Plan an evening outside

Every object, one by one