Cassini Observes Summer Solstice in Saturn, Prepares for Sixth Ring-Grazing Orbit

NASA's Cassini spacecraft is preparing for its sixth ring-grazing orbit. While at it, the spacecraft observed summer solstice in Saturn.

Few months before its mission ends in September, Cassini witnessed amazing activities in Saturn. Cassini filmed Saturn's solstice or the longest day of summer in the northern hemisphere of the ringed planet and the short winter in the southern hemisphere.

Saturnian solstice, according to experts, occurs only every 15 Earth years. Documenting and observing the solstice is one of the main missions of Cassini. In fact, the name of the probe's extended mission is Cassini Solstice Mission.

"During Cassini's Solstice Mission, we have witnessed - up close for the first time -- an entire season at Saturn," Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California said in a statement. "The Saturn system undergoes dramatic transitions from winter to summer, and thanks to Cassini, we had a ringside seat."

During the Cassini Solstice Mission, Cassini observes a giant storm as it encircles the planet. The storm also caused the disappearance of blue hues that used to be visible in the northern hemisphere. The haze is one key feature that differentiates Saturn's atmosphere from Jupiter.

But the haze isn't just aesthetic feature of Saturn. Experts say that haze actually influences the changing temperatures and chemical composition of the planet's atmosphere. Researchers discovered that traces of hydrocarbon compounds like ethane, propane and acetylene react quickly than others to the sunlight.

"Eventually, a whole hemisphere undergoes change, but it gets there by these jumps at specific latitude bands at different times in the season," Robert West, a Cassini imaging team member at JPL said in the same report.

In the images, the surface of Saturn in its original state appears to have blue hue highlights, while the blue tends to disappear during the solstice as photographed by Cassini. The color changes are results of image comparison from 2013 to 2017.

After the astonishing observation, Cassini will pass 3,810 kilometers within Saturn's D ring for its sixth ring-grazing. This will be the closest pass of the mission.