On Thursday, NASA's Cassini met a new milestone with start of the solstice on Saturn. The spacecraft is now busy observing the seasonal changes in the Saturn system and reporting the data to scientists on Earth.

Cassini mission

Cassini—the 22-foot-high and 13-foot-wide spacecraft—was launched in 1997 with the primary goal to study the atmosphere of Saturn and its icy moons. The probe arrived at the ringed planet in 2004, and since then, it has been sending data to scientists on Earth. After Cassini completed its primary, four-year-long mission in 2008, it was granted its first extended mission—called the Equinox Mission—to observe Saturn’s ring structures.

This mission ended in 2010, and then a second extended mission of seven years, called Solstice Mission, was granted to Cassini by NASA. The goal of this mission was to reach Saturn’s solstice and observe seasonal changes on the planet.

What is Saturn’s solstice?

Saturn's solstice means the longest summer day in Saturn’s northern hemisphere and the shortest winter day in the southern hemisphere. The solstice on Saturn occurs every 15 Earth years thanks to the slow orbit of the planet around the sun.

According to Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Cassini's Solstice Mission has allowed scientists to witness a complete season at the ringed planet. A major event that Cassini saw during Solstice Mission was a giant storm encircling the planet.

The probe also witnessed how blue hues, which had stayed in the far north of the planet, disappeared after formation of springtime hazes there. Cassini has also observed several major changes occurring on Saturn's largest moon, Titan. In 2004, Cassini observed the dramatic activity of methane storm clouds around the south pole of Titan.

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In 2010, the Cassini’s cameras captured giant storms transition into Titan's equator.

Cassini’s final journey

The Saturn probe is currently in the final phase of its mission—the Grand Finale—which started on April 26 and is scheduled to end on September 15. According to the American space agency, Cassini has almost completed its life, and the time is now quickly approaching to say goodbye to the spacecraft.

The probe is currently moving at a speed of over 70,000 miles per hour and is exploring the wide gap between Saturn’s atmosphere and its rings. This last phase of Cassini’s journey is expected to shed light on Saturn’s mysterious rings, their formation, their mass, and their age. On September 15, the spacecraft will take a final plunge into Saturn’s atmosphere to eventually vaporize, thus bringing an end to the grand journey of this spacecraft.