Starting this weekend, Saturn’s famous rings will appear to “disappear” for a few days when viewed from Earth. This rare phenomenon, called “ring plane crossing,” happens once every 13 to 15 years. Although the rings won’t actually vanish, they will look nearly invisible due to Saturn’s position in space. The last time this occurred was in 2009.

The event will begin on Sunday, March 23, at 16:04 GMT, and it is expected to last for a short period.

Why do Saturn’s rings seem to vanish?

The ring will disappear due to Saturn’s tilted axis and its position relative to Earth. Saturn’s axis is tilted at 26.73 degrees, while Earth’s axis tilts at 23.5 degrees. Because both planets orbit the Sun, there comes a time when Saturn’s rings align perfectly with Earth’s line of sight. This alignment causes the rings to look like a thin line of light, making them almost impossible to see.

“They literally almost disappear,” explained Sean Walker, associate editor at Sky & Telescope, a magazine about science and astronomy.

Normally, Saturn’s rings are clearly visible, even through a telescope. However, during this event, the rings will appear so thin that they’ll look like a faint line cutting across the planet. According to Walker, “It looked like a different planet” when he saw a ring plane crossing in 1995 through his backyard telescope.

“It was fantastic! I spent a good part of the night just drinking in that view,” he added.

Unfortunately, skywatchers won’t be able to catch this rare sight because Saturn will be positioned too close to the Sun during the event. Even though the view may not be visible this time, the rings have been gradually appearing thinner in recent months when seen through ground-based telescopes.

How often does this happen?

Saturn takes 29.4 years to complete one orbit around the Sun. During this long journey, the ring plane crossing happens twice. The next time you can expect to see this fascinating event will be in 2038.

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