At the California Science Center’s latest Lunch and Learn, Project Manager and Mars Specialist, Devin Waller, walked a group of around 25 financial contributors of the CSC from the Sun to Saturn. The distance from Saturn (the sixth planet from the sun) and the actual sun spans approximately 891 million miles. Our stroll through a mock model of the solar system built by Science Center employees wasn’t quite as far as that. The walk itself could have been completed in no more than 5 minutes had Devin not gifted us with the engineering and scientific perspectives involved in replicating our universe. Models like the one pictured below help students and visitors of the California Science Center understand the intricacies of space.
We began at the Sun– a 4.5-billion-year old star that accounts for 99.86 percent of the mass in our solar system. Given its size, it is estimated that over one million Earths could fit inside of the sun! This giant ball of gas is composed of 70 percent hydrogen and 28 percent helium. As the two gases react, intense amounts of energy and heat are created. Without this energy, there would be no life on Earth.
Next we arrived at the smallest and innermost planet, Mercury. Mercury orbits the sun in just 88 days, making the shortest orbit of any planet. Each complete orbit around the sun represents one “year,” while a rotation on a planet’s axis represents one “day.” Its temperature ranges from -297 on the side opposite the sun to + 800 degrees on the side facing the sun. Because Mercury is so close to the sun, it is hard to directly observe from Earth except during the hours of dawn or twilight.
The second planet we visited was Venus, a celestial body located 67 million miles from the Sun. Known as the rocky planet, Venus has the longest rotation of the solar system family and has a scorching temperature of 896 degrees. It takes 224 Earth days for Venus to experience one “day.” Unlike most other planets in the Solar System, which rotate on their axes in a counter-clockwise direction, Venus rotates clockwise (this is called “retrograde” rotation). Our home, Earth, is the third planet in line from the sun. One rotation on Earth takes 24 hours with a complete orbit around the sun lasting 365 days. Our planet’s average temperature is a balmy 61 degrees. In contrast, Mars is a rocky planet 141,700,000 miles from the sun that has a temperature of -81 degrees. With its thin atmosphere and lack of liquid water, winds drive the global conditions. NASA space projects have been studying Mars since the 1960s. According to NASA, the goal of the Mars Exploration Program has been to provide a continuous flow of scientific information and discovery through a carefully-selected series of robotic orbiters, landers and mobile laboratories interconnected by a high-bandwidth Mars/Earth communications network. Mercury, Venus, Earth, and Mars represent the terrestrial planets: inner planets closest to the Sun that are composed primarily of silicate rocks or metals.
As our tour moved on to the outer planets, we stopped at a replica of the gas giant known as Jupiter—the largest planet in our Solar System. Like the Sun, Jupiter is composed of hydrogen and helium yet it is a cold planet (minus 234 degrees Fahrenheit). Its massive size and distance from the sun (483,500,000 miles) makes it so that it takes 11.86 years for Jupiter to complete an orbit. It has 67 known moons and like Saturn, Jupiter has rings. Unlike the vivid, icy rings of Saturn, Jupiter’s rings are subtle, sandy structures.
Our final stops on the walking tour took us to Saturn, one of the most visually stunning celestial bodies in our Solar System, and a replica of the spacecraft Cassini, which spent over a decade studying Saturn. We had the great privilege of listening as Dr. Jo Pitesky, an engineer at the Jet Propulsion Laboratory who worked with Cassini from 2001 until 2017, provide details about Cassini and its twenty-year mission. Cassini was the latest NASA spacecraft to explore Saturn, completing its journey on September 15th, 2017. Cassini launched in 1997 and arrived at Saturn seven years later. In that time, the spacecraft captured stunning photos of the planet’s weather systems (including the changing seasons in the Northern Hemisphere), magnificent rings, and it’s 62 moons while providing invaluable data on Saturn and its atmosphere. Cassini viewed, listened, smelled, and even tasted Saturn’s moons– and what it learned about them is nothing short of remarkable. Probing Saturn’s icy moons, Cassini discovered that water is continually spewing out of jets around the southern pole of Saturn’s moon Enceladus. It also found liquid water on Saturn’s largest moon, Titan. These extraordinary discoveries indicate that Enceladus and Titan have all of the ingredients necessary for life and make future space exploration all the more exciting. The “Grand Finale Orbits” that carried Cassini to its end helped solve longtime mysteries such as the planet’s rate of rotation, the length of a day on Saturn, and the mass of its stunning rings. Dr. Pitesky made her commitment to the project transparent, explaining that she could spend weeks describing Cassini accomplishments.
The start of Cassini’s final voyage began on September 12th, 2017. Cassini continued transmitting messages as long as possible until the force of Saturn’s atmosphere overpowered the spacecraft thrusters and Cassini could no longer make contact with Earth. At 3:31 am (PDT) on September 15th, 2017, Cassini’s final signal was received. As Dr. Jo Pitesky narrated the extraordinary life of Cassini and its final descent to Saturn, it was hard to find a dry eye in the room. Showing us photos of the thousands of men and women involved in the Cassini mission– to provide information and educate the world– she likened its journey to the following quote.
“Though here at journey’s end I lie
in darkness buried deep,
beyond all towers strong and high,
beyond all mountains steep,
above all shadows rides the Sun
and Stars for ever dwell:
I will not say the Day is done,
nor bid the Stars farewell.”
J. R. R. Tolkein