So long as clouds don’t get in the way this evening, Jupiter and Saturn will appear at their closest in almost 800 years.
Astronomers call such an event a “great conjunction,” and you can see it with the naked eye. Even better, the planets’ apparent closeness means they’ll also be visible in the same field of view when viewed through binoculars or a small telescope.
The last time Jupiter and Saturn appeared this close was in 1623, but the event was hard to see from Earth because of its close proximity to the sun. It means that the last time they were this close and easy to see was way back in 1226 — when Genghis Khan was busy conquering Asia.
NASA suggests looking for Jupiter and Saturn in the southwest in the hour after sunset on Monday night, adding, “On the 21st, they will appear so close that a pinkie finger at arm’s length will easily cover both planets in the sky. ”
The space agency offers also offers precise instructions on how to view the two planets in the night sky:
- Find a spot with an unobstructed view of the sky, such as a field or park. Jupiter and Saturn are bright, so they can be seen even from most cities.
- An hour after sunset, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.
- The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons orbiting the giant planet.
NASA says a great conjunction takes place around every 20 years as the orbits of Earth, Jupiter, and Saturn periodically align, making the two planets appear close together in the night sky.
In reality, Jupiter and Saturn are more than 450 million miles (724 million km) apart — with Earth 550 million miles (885 million kilometers) from Jupiter, the nearest of the two planets.
And don’t worry if you miss the spectacle on Monday — Jupiter and Saturn will still appear close together for a while yet.
- How to watch the conjunction of Jupiter, Mercury, and Saturn tonight
- How to watch the Geminids meteor shower tonight
- Our galaxy is lonelier than we thought, New Horizons data shows
- NASA is kicking off two missions to help understand space weather
- International Space Station has a major upgrade task coming