The Aphelion reference library
Find something in the sky.
47 results
The collection
The Best Gifts for Astronomers & Space Lovers
The best gift for an astronomer matches what they love about the sky. Here's a guide sorted by the kind of stargazer you're buying for.
The collection
The collection
Subject by subject: the Moon, the planets, galaxies, nebulae, blueprints and the retro travel posters.
More guides and references
The observatory journal
Start with a question about the sky, explore the objects beyond it, or find practical help choosing and printing your own artwork.
Your own sky
Turn a Photo Into Wall Art: 4 Styles Compared
There's more than one way to turn a photo into wall art. Here are four distinct styles, and the kind of photo each one flatters most.
Looking up
What causes the northern lights?
An aurora is the sky glowing where the solar wind meets Earth's magnetic field. Here's what causes it, where to see one, and why the colours differ.
On the wall
What DPI Do You Need to Print a Photo?
As a rule: aim for 300 DPI for a crisp print, accept down to 150 DPI for larger pieces, and avoid anything below that. Here's what those numbers mean for your photo.
Looking up
What Is a Constellation? The 88 Patterns, Explained
A constellation is a recognised pattern of stars: and, in the modern sense, a defined patch of sky around it. There are 88 official ones, set by the International Astronomical Union, and together they map the e…
Looking up
What Is a Nebula? The Main Types, Explained
A nebula is a vast cloud of gas and dust in space: some are stellar nurseries, others the remains of dying stars. Here are the main types and the famous examples.
Your own sky
What is a star map print?
A star map print shows the sky as it actually appeared above one location at one moment: a specific date, time and set of coordinates, plotted rather than illustrated.
On the wall
What is the 2/3 rule for wall art?
The 2/3 rule says a picture hung above a piece of furniture should be about two-thirds as wide as the furniture beneath it. It is a decorating rule of thumb, not a standard anyone enforces.
Looking up
What Is the Pale Blue Dot?
The Pale Blue Dot is a 1990 photograph of Earth taken by Voyager 1 from six billion kilometres away, our entire world reduced to a single point of light.
On the wall
What is the perfect size for wall art?
There is no single perfect size. The right one is set by the wall, not the picture. The common guidance is to fill roughly two-thirds to three-quarters of the available width.
The collection
What to gift someone who loves the moon?
Choose by what they actually love about it: the object itself, the cycle of phases, or one particular night. Those are three different gifts and only one of them will land.
Looking up
When were galaxy prints popular?
The galaxy print you are thinking of (leggings, hoodies, bedding) was a clothing and bedding trend, and an early-2010s one in our reading. Deep-space imagery as wall art is a separate thing and did not rise or …
Looking up
Wolf Moon: January’s full moon
January’s full moon, full on Saturday 3 January 2026 at 10:03am GMT. The name is folk history rather than astronomy, and the date is the part worth getting right.
Looking up
Worm Moon: March’s full moon
March’s full moon, full on Tuesday 3 March 2026 at 11:38am GMT. The name is folk history rather than astronomy, and the date is the part worth getting right.
Your own sky
Your own sky
One particular night, or one particular photograph. What a star map shows, and what happens to a photo you upload.