A list of things to ignore
An eighteenth-century comet hunter kept noting fuzzy objects that were NOT comets so he would stop being fooled by them. That list of nuisances is now the most-used observing programme there is.
The whole visible field
Everything out there is faint.
Not far, not rare. Faint. A hundred thousand stars packed into a ball, a dying star lit from inside, the wreck of an explosion still opening outward — all of it sits above a dark horizon waiting for an eye that has stopped expecting brightness.
Each entry says what the object is, how far off it lies, and what it looks like through glass rather than in a photograph.
Start here
Three that change how the rest of the site reads
Why almost everything is grey
The eye's low-light system carries no colour. Photographs are not lying, but they are not what you will see.
The photographs on this site are true and they are not what you will see. Understanding why is the difference between disappointment and a long observing life.
A hundred thousand stars in a ball
Globulars are older than the galaxy's disc and orbit it as a halo. Through glass they resolve at the edges before the middle.
Supported by
Observatories and societies that keep watch on the same catalogues.
The catalogues
A list of things to ignore became the list everybody uses.
Charles Messier hunted comets, and the sky kept producing faint smudges that were not comets. He wrote them down so he would stop being fooled by the same objects twice — a register of nuisances, not a collection of wonders.
He is remembered now for none of the comets he found and all of the objects he dismissed. Read the whole story, or start with why the numbers are in no useful order.
- 1771First version, 45 objects, published by the Académie Royale des Sciences in Paris
- By 1784Messier’s own edition has grown to 103 entries
- 1888The New General Catalogue arrives with nearly 8,000 entries and never displaces him
- Standard today110 objects, incorporating Méchain’s independent discoveries
Six sections
Twenty-five guides, filed by what the object is
01
Clusters
Stars that formed together and stayed.
4 guides 02Nebulae
Gas lit from inside or from nearby.
4 guides 03Remnants
What is left after a star fails.
3 guides 04Galaxies
Other systems, seen edge-on and face-on.
5 guides 05Catalogues
Lists made for other reasons entirely.
4 guides 06Observing
Why it is grey, and how to see more of it.
5 guidesObserving
The eye is the instrument that limits all of this.
Nothing here is about equipment. It is about what the eye can be persuaded to register, how long that takes, and how quickly one white light undoes it.
- 01Why almost everything is greyThe eye's low-light system carries no colour. Photographs are not lying, but they are not what you will see.
- 02Dark adaptationIt takes far longer than people allow, and one white light undoes it.
- 03Averted visionLooking slightly away to see something faint, and why that works.
- 04Seeing and transparencyA steady sky and a clear sky are different things and rarely arrive together.
- 05How dark is darkNaming sky brightness, and what each step actually costs you.
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Observatories and societies we navigate by.