BENGALURU: Saturn, known for its iconic rings, will appear “ringless” in the upcoming days - around March 23 - due to a rare event called a ring-plane crossing. This rare phenomenon, which happens once in 15 years, happens when Earth aligns perfectly with Saturn’s equator, causing the rings to tilt edge-on from our viewpoint.
Researchers explained that Saturn’s rings are easily visible from Earth, however, they are thousands of kilometres wide, but extremely thin - only 10 to 30 metres thick in many places. While we can see the rings clearly as they are made of ice, which reflects sunlight very well, the brightness of the rings changes based on the angle at which sunlight hits them and the angle from which we see them from Earth.
Saturn, the second largest planet, tilts on its axis, just like Earth. As Saturn orbits the Sun in its 29.5-year-long journey, this tilt causes the view of the rings to change. Sometimes, the viewer sees the rings at a wide angle, making them appear broad and bright. At other times, we see them from the other side, where they appear much thinner, BR Guruprasad, Director of the Jawaharlal Nehru Planetarium (JNP) said.
The ‘ring-plane crossing’ happens when Saturn’s rings align edge-on with Earth. Because the rings are incredibly thin, they become invisible from our perspective, Guruprasad said.
“It is like looking at a sheet of paper from its edge - one can barely see it,” he explained, adding that only Saturn experiences such an effect among the ringed planets, as its rings are far thinner compared to those of Jupiter, Uranus, or Neptune, whose rings are made of darker, less reflective material and are much fainter overall.
The last ring-plane crossing occurred in 2009, and it will happen again in 2040. Researchers explained that for a few months before and after the exact crossing, the rings will be difficult to detect, even with telescopes.