Unseen Cosmos is an illustrated guide to places in space that no camera has ever reached: planets around other stars, black holes, the largest and strangest stars, the far edge of the Solar System, and ideas such as Dyson spheres and the multiverse that may exist only on paper.
Almost everything here is known from measurement rather than from pictures. A planet hundreds of light-years away is a slight dip in a star’s light; a black hole is the way stars move around a point that gives off nothing at all. The pages set out what has been measured, and the pictures show what those measurements might look like.
The pages
Every page is written by hand from named sources, listed at the foot of the page and linked from each fact. Most of the numbers come from NASA, ESA and ESO, the NASA Exoplanet Archive, JPL’s Small-Body Database, the published papers behind each discovery, and the Wikipedia articles that summarise them. Where measurements disagree, the page says so and gives the range. Where an object is hypothetical, disputed or never observed, a label at the top of the page says that too.
Temperatures are given in kelvin and in degrees Celsius. Large numbers use a space rather than a comma to separate thousands.
The pictures
Every image on this site is an artist’s impression. None of them is a photograph, and none should be read as one. Each page says what its picture is based on and what is imagined. How the pictures are made, and what you may do with them, is explained on the illustrations page.
Corrections
If a number, a date or a claim on any page is wrong, please write to hello@unseencosmos.com with the source, and it will be fixed.
Who runs this
Unseen Cosmos is run by Samu Leino in Finland. The site has no accounts, no sign-up and no comments. What little data it collects is described on the privacy page.