Look up to see Saturn at its brightest in 15 years this weekend
On the night of "Saturn's Day" the planet will shine brightly in the sky!
The ringed planet, Saturn, reaches "Opposition" this weekend, when it will be positioned on the exact opposite side of Earth from the Sun, and we will see the planet at its brightest in the sky since 2010!
As the planets travel around the Sun and through our skies, astronomers track specific dates of the year when we can see these members of our celestial family at their biggest and brightest.
For Mercury and Venus, their closest approaches to Earth are known as 'inferior conjunctions', which put them directly in between us and the Sun. This, unfortunately, makes them nearly invisible to us at those times. Not only does the bright light of day interfere with observations, but they both present their dark side to us, similar to the New Moon. The only time we can see this is during a transit, when the planet in question crosses the face of the Sun.
The rest of planets reach their closest to Earth either at or near what is known as opposition, when they are on the exact opposite side of Earth from the Sun.
Saturn Opposition, on September 20-21, 2025. (Celestia/Scott Sutherland)
For Saturn, its next opposition occurs on the night of September 20-21.
During that night, the planet will rise in the east at sunset on Saturday, and cross the sky to set in the west at sunrise on Sunday.
At around 1:45 a.m. EDT, Saturn reaches its exact opposition point for 2025.
Saturn in the southern sky during Opposition, on the night of September 20-21, 2025. The inset image, right, shows a telescopic view of the planet and its most prominent moons at 1:45 a.m. EDT. (Stellarium/Scott Sutherland)
Saturn Oppositions come around roughly once every 378 days. This is longer than an Earth year because as we travel around the Sun to catch up to Saturn again, Saturn has also spent one Earth-year moving much slower along its own orbit. So, the distance travelled by Saturn adds about 2 extra weeks (give or take a day or so) to our journey so we can align once again.
Saturn is not only in alignment with the Sun and Earth this weekend, it is also at its closest point to us, at a distance of 8.547 astronomical units or 1.278 billion kilometres. (An astronomical unit, or au, is the average distance between Earth and the Sun.)
That will put Saturn at its closest to Earth, and also its brightest in our night sky in over 15 years.
Saturn and its brightest moons through a powerful telescope during Opposition 2025. (Stellarium/Scott Sutherland)
Since Earth's and Saturn's orbits are not perfectly circular, the distance between the two planets changes each time they reach opposition. In fact, following a consistent 3-decade-long cycle, the two start at a minimum distance in late December, get farther apart with each subsequent opposition up to a maximum distance in late June, and then get closer together for each opposition after, until they reach the next minimum distance again in late December.
This latest cycle began on Dec 31, 2003, when Earth and Saturn reached opposition at around 1.2 billion km apart. On June 27, 2018, they were at their farthest opposition of this cycle, at a distance of just over 1.35 billion km.
In 2025, we're at the halfway point between that 2018 maximum and the next minimum opposition, which will take place on December 24, 2032. Thus, year after year, we are seeing closer and brighter oppositions.
This weekend, Saturn will be brighter in our sky than at any point going back to April of 2010, just after it reached opposition in March of that year. Then, for each opposition after this, the planet will be closer and brighter, right up until December 24, 2032.
On that night, we'll apparently get a special look at Saturn. The ringed planet will be closer to Earth, and brighter in our night sky, than at any point going back to December 1914!
(Thumbnail image depicts a close-up view of Saturn at the moment of Opposition 2025, as simulated by the astronomical program Celestia)