How to watch Jupiter and Venus as they join in the sky this week

You may have noticed two bright "stars" in the west after sunset. Those aren't stars, but two planets: Jupiter and Venus. And they're on their way to a beautiful meet-up in the days ahead.

While they will look close together in the sky, they are still very far apart: they lie roughly 670 million kilometres from each other.

Venus has been rising steadily in the sky since the beginning of May. Meanwhile, Jupiter has been sinking toward the west.

You can find the pair in the west after sunset. Venus will be the brighter of the two and lower on the horizon.

Conjunctions are a great reminder that space isn't as static as we think.

"The two brightest planets low in the evening sky generate lots of interest and are easy and convenient to see with the naked eye," said Paul Delaney, professor emeritus at York University's Department of Physics and Astronomy.

"They easily show from day to day the movement of objects in the solar system."

As they near each other, Venus will overtake Jupiter and appear higher in the sky.

You can see them just over a degree apart on June 8. On June 9, they will be even closer.

These meet-ups of objects in the sky are technically called appulses, but they are more commonly known as conjunctions.

You don't have to wait until the two are closest to each another. Instead, you can track them over the coming days as they move across the sky.

To see them, you just need a good view of the western sky.

And not to be forgotten is Mercury. On the nights of June 8 and 9, it will join the pair as it rises higher out of the sun's glare.

Delaney noted that planetary conjunctions happen each year, but some are closer than others, and perhaps some may be too dim to be seen.

As for Jupiter and Venus, they meet almost every three years or so, but as Delaney noted, they don't always happen in the evening sky.

Another fun thing you can do ahead of the conjunction is to watch the Jupiter's moons change position from one night to another.

Jupiter's four brightest moons are Io, Callisto, Europa and Ganymede. They orbit Jupiter very quickly — so quickly, in fact, that even during a single night, you can see them change positions.

On June 1 at 9:30 p.m. local time, Io, Callisto and Europa would be on the left side of the planet, with Ganymede on the right.

But if you observe it the following night at the same time, you will see only Callisto to the left, as Io and Ganymede will be behind Jupiter and Europa will be passing in front.

If you're not sure what you're looking at, you can check with Sky & Telescope's Jupiter Moons tool, or download night sky apps that will help you identify objects in the sky.