SKY · FIELD GUIDE
Conjunctions, Oppositions & Planet Parades — What the Words Mean
The sky-events calendar is full of words like conjunction, opposition and parade. Which ones are real spectacles you should set a reminder for — and which are just two dots that happen to line up? Here's how to read them.
Open any astronomy calendar and you'll hit a wall of words: conjunction, opposition, elongation, parade, appulse. Most of them describe the same simple thing — where things are in the sky relative to each other and to the Sun — dressed up in technical language. Here's what they actually mean, and which ones are worth setting a reminder for.
Conjunction: two things line up
A conjunction is the most common entry on the calendar. It just means two objects appear close together in our sky. The key word is appear — they're nowhere near each other in space. When the Moon has a conjunction with Jupiter, the Moon is about 380,000 km away and Jupiter is the better part of a billion kilometres beyond it. They only share a direction.
The ones worth watching are the close conjunctions, where two genuinely bright objects come within a degree or two — about the width of your fingertip at arm's length. Venus and Jupiter, the two brightest planets, having a close pass is one of the finest naked-eye sights in astronomy, and easily photographed with a phone.
Opposition: the best night to see an outer planet
For Mars, Jupiter and Saturn, opposition is the date that matters most. It's when Earth slides directly between that planet and the Sun, so the planet sits opposite the Sun in our sky. The payoff is everything at once: the planet rises as the Sun sets, stays up the whole night, climbs highest around midnight, and is at its closest to Earth — so it's also at its biggest and brightest for the year. If you're going to point a telescope at Saturn's rings once this year, do it within a few weeks of opposition.
Planet parade: several planets at once
A planet parade is the crowd-pleaser, and it's a popular term rather than a strict scientific one. It's what we call it when several naked-eye planets are up at the same time, usually strung along the sky after dusk or before dawn. Three is common and pretty; four or five together is a genuine event. They appear in a line because the Solar System is essentially flat — every major planet orbits in nearly the same plane, and we view that plane edge-on, as a line across our sky called the ecliptic.
How to tell what's worth it
Not every calendar entry deserves a cold night outside. A rough guide: a close conjunction of bright planets or the Moon beside a bright planet is an easy, lovely naked-eye sight; an opposition is the year's best look at an outer planet through any optics; a parade of three or more is worth planning around. A conjunction of two faint planets a long way apart, on the other hand, is more of a "nice to know" than a "set an alarm." Our events pages flag the genuine highlights, and each city page tells you when and which way to look from where you are.
Frequently asked questions
What is a conjunction?
A conjunction is when two objects appear close together in the sky from our point of view on Earth. They aren't actually near each other in space — a conjunction of the Moon and Jupiter has the Moon a quarter-million miles away and Jupiter hundreds of millions of miles beyond it — they just happen to line up along nearly the same direction. The closest, prettiest conjunctions put two bright objects within a degree or two, close enough to fit in the same binocular view or a single photo.
What is an opposition, and why does it matter?
An outer planet (Mars, Jupiter, Saturn) is 'at opposition' when Earth passes directly between it and the Sun, so the planet sits opposite the Sun in our sky. That's the best time to see it all year: it rises at sunset, is up all night, sits at its highest around midnight, and is at its closest and brightest. If you only look at Saturn or Jupiter once a year, opposition is the night to do it.
What is a planet parade?
'Planet parade' isn't a formal astronomical term — it's the popular name for when several naked-eye planets are visible in the sky at the same time, usually strung along the same part of the sky after sunset or before dawn. Three planets at once is common; four or five together is genuinely worth getting up for. They look like a line because the planets all orbit in roughly the same flat plane, which we see edge-on as a line across the sky.
Why do planets line up in a line across the sky?
Because the entire Solar System is nearly flat — all the major planets orbit the Sun in roughly the same plane, like marbles rolling on a tabletop. We're inside that plane looking out, so that plane projects onto our sky as a line called the ecliptic. The Sun, Moon and planets all travel along it, which is why a 'parade' looks like beads on a string rather than dots scattered everywhere.
Are these events visible from anywhere on Earth?
Mostly yes, but the timing and direction change with your location, which is why our events pages let you pick your city. The event itself — say, Venus and Jupiter at their closest — happens at one instant worldwide, but whether the pair is above your horizon then, and which way you'd look, depends on where you are and your local time. Some events also favour one hemisphere over the other.
Do I need a telescope to see a conjunction or parade?
Usually not. The headline conjunctions and parades involve naked-eye planets (Venus, Mars, Jupiter, Saturn) and the Moon, all easily visible without any equipment from a reasonably clear spot. Binoculars make a close conjunction lovely — you can often fit both objects in one view — and a small telescope adds detail like Jupiter's moons or Saturn's rings, but the lining-up itself is a naked-eye event.
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