Naked-eye astronomy is underrated. Most people’s first instinct is that seeing anything interesting requires equipment, and then the equipment sits unused in a cupboard. The truth is that the sky offers a rotating programme of things worth looking at, and knowing what is up tonight is most of the skill.
Here is a framework for observing any season, rather than a list that goes stale in a fortnight.
Start with the planets
Five planets are visible without any optical aid, and they are the easiest wins available.
- Venus is unmistakable — the brightest thing in the sky after the Sun and Moon, appearing either in the west after sunset or the east before sunrise, never far from the Sun.
- Jupiter is the next brightest, holds steady, and rewards even modest binoculars by showing its four largest moons as a line of pinpricks that shifts night to night.
- Mars varies enormously. Near opposition it is a striking orange beacon; at other times it is unremarkable.
- Saturn is a steady yellowish point to the eye. Any small telescope shows the rings, which is the single most reliable way to convert a sceptic.
- Mercury is the difficult one, always low and lost in twilight, visible only during brief windows near its greatest elongations.
The reliable way to tell a planet from a star is that stars twinkle and planets generally do not. Stars are point sources, so atmospheric turbulence makes them flicker; planets present a tiny disk, which averages the turbulence out.
Let the Moon set your schedule
The Moon is both the best target for beginners and the biggest obstacle to everything else, so it is worth planning around rather than ignoring.
For lunar observing, avoid full Moon. It sounds backwards, but a full Moon is lit straight-on, which flattens all the shadows and washes out detail. The rewarding views are along the terminator — the line dividing day from night — where low-angle sunlight throws crater rims and mountain ranges into sharp relief. A first-quarter or last-quarter Moon shows dramatically more texture than a full one.
For everything else — galaxies, nebulae, meteor showers, the Milky Way — you want the Moon out of the sky entirely. The week around new Moon is the dark-sky window.
Two roughly week-long windows each month: one for the Moon, one for everything else.
The seasonal headliners
Earth’s orbit means we face a different part of the galaxy at different times of year, and the character of the sky changes with it.
Northern-hemisphere winter evenings look outward, away from the galactic centre, toward the nearby star-forming regions in Orion. This is the brightest, most easily recognised stretch of sky, with the Orion Nebula visible to the naked eye as a fuzzy patch in the sword.
Spring evenings look up out of the galactic plane, so there are fewer bright stars but a clear view into intergalactic space — the direction of the great galaxy clusters, though these need a telescope.
Summer evenings face the galactic centre. The Milky Way is at its densest and brightest, threading through Sagittarius and Scorpius, dense with star clusters and nebulae. From a dark site this is the best sky of the year.
Autumn brings the Andromeda Galaxy high overhead, the most distant object routinely visible to the unaided eye at roughly two and a half million light years.
Practical habits
A few things make the difference between a pleasant hour and a frustrating one.
Give your eyes twenty to thirty minutes to adapt, and protect that adaptation ruthlessly. One glance at a phone screen resets it.
Learn to use averted vision. Look slightly to the side of a faint object rather than directly at it; the periphery of the retina is far more sensitive in low light, and faint galaxies often pop into view when you stop staring at them.
Check the transparency, not just the cloud cover. A haze-free night with steady air shows far more than a technically clear but humid one.
And use a planetarium app to plan before you go out, then put the phone away once you are outside.