Ultra-sharp Hubble view shows 'ghostly' seasonal phenomenon on Saturn
Data from the Hubble Space Telescope has captured an image of Saturn when the planet was approximately 1,365 million kilometers from Earth.. Ultra-sharp vision reveals a 'ghostly' phenomenon in the rings known as spokes.
The snapshot, made public this Thursday by the American space agency NASA and the European Space Agency (ESA), is dated October 22.
Saturn's spokes are transient features that rotate together with the rings and their “ghostly appearance” only persists for two or three rotations around Saturn, reports from ESA and NASA.
In 1981, NASA's Voyager 2 first photographed the rings' radii, and the Cassini orbiter also observed them during its 13-year mission that ended in 2017.
Hubble continues to observe Saturn annually as radios come and go. This cycle has been captured by Hubble's OPAL program that began nearly a decade ago to annually monitor climate changes on the outer gas giant planets.
Their clear images show that the frequency of radio appearances is seasonal.
Long-term monitoring shows that both the number and contrast of rays vary with the seasons of Saturn. The planet is tilted on its axis like Earth and has seasons that last approximately seven years.
“We are heading toward the Saturn equinox, when maximum radio activity is expected, and darker, higher frequency radios will appear in the coming years,” explains OPAL program lead scientist Amy Simon of the Goddard Flight Center. NASA Space Station in Greenbelt (Maryland).
This year, these ephemeral structures appear on both sides of the planet simultaneously as they orbit the giant world. Although they appear small compared to Saturn, their length and width can extend further than the diameter of Earth.
There are several theories, but the main one is that the radii are linked to interactions between Saturn's powerful magnetic field and the sun.. After several decades, no one perfectly predicts this phenomenon.
Continued observations by Hubble, a NASA and ESA project, may help solve the mystery.