Are Star Maps Accurate? What a Star Map Actually Shows

A star map is meant to show the sky as it was over a particular place at a particular moment: the night you met, the night a baby was born, the night you got married. It's a lovely idea, but it only means something if the sky is actually right. So, are they accurate?

Some aren't. Some shops use the same handful of skies, or ignore the time of night. Here's what ours does, so you know what you're getting.

What our star map shows

• The real position of every star visible to the naked eye from a dark place: just over 5,000 stars, down to magnitude 6.
• All 89 constellations above the horizon, with their lines and names if you want them.
• The Milky Way, where it crossed the sky that night.
• The whole sky from horizon to horizon, as a circle, with the point straight overhead in the middle.

The positions are worked out with standard astronomy software from your place's latitude and longitude and the exact date and time, including the slow wobble of the Earth's axis over the years. We tested it against the real sky: Polaris sits at the right height for the latitude, and the stars appear where their published positions put them.

Why east and west look swapped

On a star map, east is on the left and west on the right, the opposite of a road map. That's because a road map looks down at the ground, and a star map looks up. Lie on your back with your head to the north and the sky is laid out exactly as it is on the print.

Time zones and summer time

You enter the time on UK clocks, as you remember it, and we handle British Summer Time for you. A baby born at 4.12am in March and a wedding first dance at 10pm in June both come out right.

What if it was daytime?

The stars were still there, just hidden by daylight. A star map of a daytime wedding shows exactly the stars that were over you, even though you couldn't see them. Some people like to put that on the print: "The stars were there, even if we couldn't see them."

What you choose

The place (anywhere in the UK), any date from 1900 to 2100, the time, one of four designs, which parts to show (constellation lines and names, a grid, the Milky Way) and your own words. You see the whole poster before you pay, and prints start at £14.95 for A4.

Ideas for the moment

• The night a baby was born, with the weight and time in the small line.
• Your wedding night, or the moment of the first dance.
• The night she became a mum, for Mother's Day.
• The night it all started, for Valentine's Day.

If you'd like the moon instead of the stars, our moon print shows the real phase of the moon on your date.

Make your star map →