Saturn's rings will 'disappear' briefly in 2025 and forever in 100-300 million years
In three months, Saturn's iconic, icy rings will appear to disappear, giving you a preview of what the planet could look like 100 million to 300 million years from now.
On March 23, an optical illusion will make Saturn’s massive rings become nearly invisible for a few days. The temporary phenomenon is called a ring-plane crossing, during which the rings appear edge-on, or flat and thin, to observers on Earth.
But later – hundreds of millions of years in the future – a permanent, virtually ringless Saturn will become real, thanks to another process called ring rain in which gravity pulls the rings apart and vaporizes their icy chunks in the upper atmosphere, NASA researchers say.
What happens in ring-plane crossing?
Ring-plane crossings take place every 13 to 15 years, NASA says.
The ring-plane crossing in March won't be perfect, since the rings won’t appear precisely flat to us. They’ll be on a bit of an angle.
And Saturn will be in conjunction with the sun, or too close to it, making it difficult to view. The rings will gradually reappear in the months after March until they "disappear" again in November.
The ring-plane crossing is a combination of the orbital position and axial tilt of Saturn.
Saturn completes an orbit around the sun every 29.5 years. During that solar orbit, "the angle of the Saturn's rings relative to the sun varies by 26.7 degrees," NASA says. During that variation, the planet's rings are edge-on to the sun at least twice in every orbit.
Saturn is the second-largest planet in the solar system. With an equatorial diameter of nearly 75,000 miles, it's about nine times the size of Earth.
However, Saturn's seven rings are about 170,000 miles in diameter, much larger than the planet itself. Despite their massive span, the rings are relatively thin. The three main rings can range from 30 feet to 300 feet thick in most places, NASA says.
That's why the rings almost vanish when we view them during a ring-plane crossing. However, “Earthbound viewers won’t get a “ringless” view of Saturn until the triple-passing of 2038-2039,” NASA says.
What is Saturn's ring rain?
Saturn's rings are composed of mostly water ice varying in size from sand-like grains to large-sized chunks, according to space.com. Rocks and meteoroids are also part of the rings.
In Saturn's ring rain, gravity is slowly dragging the water ice from the inner rings into the planet’s upper atmosphere, where they vaporize. The inner rings will fall first and the outer rings will follow.
Ring rain “drains an amount of water products that could fill an Olympic-sized swimming pool from Saturn’s rings in half an hour," according to NASA estimates.
Saturn is estimated to be 4.6 billion years old. The planet's rings, discovered by the astronomer Galileo Galilei in 1610, are believed to be about 400 million years old.
Saturn's neighboring planets, Jupiter, Uranus and Neptune, all have rings, says the University of California, Riverside. Jupiter's large moons have prevented rings like Saturn's from forming, UCR says, while Uranus and Neptune's rings are "so flimsy they’re difficult to view with traditional stargazing instruments."
CONTRIBUTING Eric Lagatta
SOURCE Paste BN Network reporting and research; NASA-Jet Propulsion Laboratory; Reuters; space.com; earth.com; astronomy.com; sciencenews.org