In this article
What a conjunction really is
A conjunction happens when two bodies share the same ecliptic longitude, which is a fancy way of saying they line up from our point of view. The ecliptic is the path the Sun follows across the sky over the year, and the planets stay close to it. When one planet catches up with another along that path, they look like neighbours.
It is purely a line-of-sight effect. The two planets are still hundreds of millions of kilometres apart, and often one is much farther away than the other. Nothing physical happens when they pass, and the pair is no closer to touching than on any other night. What changes is the view from Earth, which can be lovely.
The Moon passing the planets
Below the planet table is a second one: the nights when the Moon slides past Venus, Mars, Jupiter or Saturn within 2°. These meetings come every month for each planet, but most are wide; the table keeps only the close ones that happen away from the Sun’s glare.
They are the easiest sky events to find: look for the Moon, and the bright “star” beside it is the planet. Because the Moon is close to us, its position shifts with your location, so the gap you see can be up to about a degree larger or smaller than listed. On the closest passes, some regions see the Moon cover the planet for a while, an event called an occultation.
How to read the table
Each row gives the date of the conjunction, the two planets, the separation and a viewing note. The separation is measured on the day they share the same ecliptic longitude, so it is the gap in the north-south direction at that moment. Sometimes the planets come a touch closer a day earlier or later, but the difference is small.
The viewing note says where to look. Evening sky means the pair stands in the west after sunset. Morning sky means it rises in the east before dawn. Too close to the Sun means the planets sit so near the Sun that twilight hides them, and you will not see them. Never point binoculars or a telescope near the Sun to look for them.
How big is a degree?
One degree is about two full Moon widths side by side, or roughly the width of your little finger held at arm's length. A pair that is 1° apart fits comfortably in one field of binoculars, and a pair at a fraction of a degree looks like a single double star to the unaided eye.
Binoculars are a fine way to enjoy a conjunction that involves Jupiter. Even a modest pair shows its four large moons as tiny points in a line beside the planet, the same four Galileo saw.
The four pairs on this site
Each pair has its own page with its rhythm and viewing tips.
- Venus and Jupiter. The two brightest planets. They meet about once a year, and sometimes twice.
- Mars and Jupiter. A red-orange point beside a creamy white one, roughly every two years.
- Venus and Saturn. A brilliant planet next to a steady golden one.
- Jupiter and Saturn. The Great Conjunction, which comes about every 20 years.
Which planets shine brightest
Venus is the brightest planet by a wide margin, and Jupiter comes second. Both outshine every star. Mars varies a lot, from fainter than Jupiter to nearly its equal, depending on how close it is to Earth. Saturn is the faintest of the four, steady and a little yellow. A conjunction with Venus or Jupiter is therefore easy to spot, even from a city.
Planets also twinkle less than stars. If a bright point in the sky shines with a calm, steady light, there is a good chance it is a planet. That is a handy trick when you are trying to tell which light in the pair is which.
Tradition and astrology
Conjunctions have been watched for thousands of years. In astrological tradition the meeting of Venus and Jupiter is called a benefic pairing, because both planets were considered kindly, and the Great Conjunction of Jupiter and Saturn was read as a shift of era. Those are matters of tradition and symbolism, and astrology has no demonstrated scientific basis.
If you enjoy a quiet night of sky watching, see the retrograde planets hub for how planets seem to slow and reverse, the Moon phases hub for choosing a dark sky, and the meteor showers for other reasons to go outside.
Questions people ask
Do conjunctions affect Earth?
No. The planets are hundreds of millions of kilometres apart and the alignment is only a trick of perspective, with no gravitational or other effect on us.
How close do two planets get?
The gap varies. Some conjunctions are a few degrees wide, others are a fraction of a degree. The table shows the figure for each one.
Do I need a telescope?
No. Venus, Jupiter and Mars are easy to see by eye. Binoculars add Jupiter's moons and make Saturn easier to pick out.
What does too close to the Sun mean?
The planets are so near the Sun in the sky that twilight hides them. Never use binoculars or a telescope to search for them.