The Gemini constellation

How we calculate this sky

We use the HYG star catalogue and compute every position with the IAU 1982 sidereal time formula followed by a stereographic projection — the same method professional planetarium software uses. The output is verified against NASA JPL Horizons.

This map shows the real night sky on February 4, seen from Central Europe. That is how Gemini stands that night — exactly as it will appear on your poster if you choose that date.

Frequently asked questions about constellation posters

Can I combine Gemini with a date of my own?

Yes, and that usually gives the most beautiful result. This page shows Gemini on the evening the constellation sits highest, but in the editor you pick any date between 1900 and 2100 yourself. Choose a date on which Gemini was above the horizon and the constellation will appear on your poster — together with the rest of the sky from that moment.

Is Gemini always on the poster?

No, and that is deliberate. We draw the sky exactly as it really looked on the date, the time and the place you enter. If Gemini was below the horizon at that moment, it will not be there — that would show a sky that never existed. The preview shows you straight away what is visible, so you can adjust the date until the image is right.

Which size suits a constellation best?

The larger the size, the more faint stars stay visible in print. For a constellation with many fine stars, 30×40 cm or larger works most comfortably; 21×30 cm is lovely when the poster hangs alongside other frames. Every size is printed at 300 DPI on 200 g/m² coated silk, unframed or framed.