One Mystery of the Solar System Has Been Solved: How Long Does a Day Lasts on Saturn?
American scientists believe they have solved a mystery about the solar system – the duration of a day on the planet Saturn. Using data from NASA’s Cassini probe, scientists have determined that a day on the sixth planet from the Sun has 10 hours, 33 minutes and 38 seconds.
For decades, scientists have tried to solve this mystery. The giant planet does not have a solid surface with defining points to be watched during rotation, and has an unusual magnetic field that hides its rotation rate. The answer, it turned out, stood in its rings, according to NASA. A year on the planet Saturn means 29 earthly years.
While Cassini orbited Saturn, the ice and rock rings were examined in detail. Christopher Mankovich, a graduate in Astronomy and Astrophysics at Santa Cruz University, used the data to study the characteristics of the waves in the rings. His research has shown that the rings respond to the vibrations emitted by the planet itself, functioning similarly to a seismometer (a tool used to measure earthquake motion).
Saturn’s interior vibrates at frequencies that cause variations in its gravitational field. The rings, in turn, detect those movements in the field. Mankovich’s research, published on January 17 in the Astrophysical Journal, shows how he developed models of Saturn’s internal structure that fit the ring movements. This allowed him to follow the movements of the planet’s interior, and thus its rotation. The rotation rate resulting from the analysis is 10:33:38, a few minutes faster than the estimate made in 1981 based on radio signals captured by NASA’s Voyager space probe.
At that time, it was estimated that one day on Saturn lasts 10:39:23, an analysis based on information given by the magnetic field. And Cassini used this type of data, but estimates ranged from 10 hours to 36 minutes and 10 hours and 48 minutes. Researchers often rely on the magnetic field to measure the rotation rate of the planets. For example, the magnetic axis of Jupiter, like the Earth, is not aligned with that of rotation. Saturn is different. Its unique magnetic field is almost perfectly aligned with the axis of rotation.
That’s why the discovery made by tracking the rings was the key to finding out the length of the day. Those studying the planet are delighted to have the best answer so far on an important question about Saturn. The idea of using Saturn rings to study Earth’s seismology was first suggested in 1982, before the observations were possible. The article published two days ago is also signed by Mark Marley, from NASA’s Ames Research Center, and by Jonathan Fortney, professor of astronomy and astrophysics at UC Santa Cruz. “Two decades later, in the last years of the Cassini mission, scientists analyzed the data and found the characteristics of the rings in the places Mark predicted (in his 1990 doctoral thesis). The work now is aimed at doing everything we can with these observations, “Fortney said. The mission of the Cassini probe ended in September 2017, when it was directed by the NASA team in the atmosphere of Saturn.
By definition, one day means the time needed for a planet to rotate around its axis (360 degrees). One year is the time it takes a planet to perform a complete rotation around the Sun.
Since the planets rotate at different speeds, the day on each of them has a different duration.
- a day on Mercury lasts for 58 days and 15 hours, in earthly terms (one day Mercury is just a little shorter than a year on the same planet).
- Venus is the slowest planet in our solar system (so slow that it remains the only one that is not the poop on the poles). One day on Venus it is equal to 243 earthly days. The day on Venus is longer than the year, which only measures 224.7 days.
- one day on Mars is equal to 24 hours, 39 minutes and 35 seconds of earth, being the most similar (as rotational speed) of Terra.
- Jupiter, the giant planet, rotates completely around the axis in just 9.9 hours of land.
- for Saturn it is estimated that the day was somewhere around 10 hours and 33 minutes
- Uranus rotates completely in 17 hours 14 minutes and 24 seconds
- Neptune has 16 hours, 6 minutes and 36 seconds of earth – Pluto needs 6.39 earth days to rotate completely around his own axis.