Conjunction of Jupiter and Venus as seen from the Giants Causeway in Northern Ireland
Stephen Emerson / Alamy Stock Photo
Tonight and tomorrow night (1st and 2nd March), skywatchers will be treated to an unusual sight as two planets will align in such a way that it will appear as if they are touching each other in space.
Jupiter, the solar system’s largest planet, and Venus, the brightest, will come together in what is called a conjunction. But what is going on?
What is it?
“Conjunctions are when two celestial bodies – usually planets – look very close in the sky from our viewpoint on Earth,” says Martin Archer at Imperial College London. “The reason it happens is all the planets around the sun orbit in roughly the same plane, called the ecliptic. That means from any given viewpoint, there might be a time where the planets would be kind of at the same angle.”
How do you see it?
It is possible to see the conjunction – visible in the western sky – with the naked eye. This is because of the size of the planets involved. But you can also use binoculars or a telescope.
How often does this happen?
That is down to Kepler’s laws of planetary motion, and how the planets orbit around the sun as a function of gravity. “It turns out these conjunctions can happen a lot,” says Archer. “Inner planets orbit faster than the Earth does, so it means from our vantage point we can get a lot of conjunctions.” Venus and Jupiter converge just over once every year.
Why are conjunctions so popular with people?
In light-polluted areas, like cities, we often don’t see many stars, but we can see planets. “With the naked eye, you can usually see planets like Venus, Jupiter and Saturn,” says Archer. “To have two of them close in the sky is pretty cool.”
Are Jupiter and Venus close in reality?
While it may seem like the two planetary bodies are touching, they actually aren’t. They are around 600 million kilometres apart, and so a conjunction is nothing to worry about – although in the past, some people did find the events concerning.
“There used to be a history of these conjunctions being a warning signal,” says Archer. “It’s literally because we’re standing in the right place in the solar system to see them close together. They’re not doing anything to one another. It’s just a pretty light show.”
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