Saturn’s iconic ring appears to “disappear” for several days starting this weekend, at least from a vantage point on Earth.
The ring does not actually disappear, but for a while the angle between Earth and Saturn creates something like an illusion of the universe, making it seem impossible to see the planetary ring from our perspective.
The reason this happens is related to the specific tilt of both planets. Saturn’s axis tilts 26.73 degrees from vertical to orbit the Sun. This is similar to the 23.5 degree tilt of the Earth. According to NASA. Therefore, as each planet rotates on its axis and orbits the Sun, the appearance of Saturn, including the ring, differs from what you see through a telescope or a powerful observatory on Earth.
Occasionally, Saturn’s tilt angle to Earth makes the ring accurately edge-on and appear to have no thin bands.
“They literally almost disappear,” said Sean Walker, associate editor of Sky & Telescope, a monthly magazine on science and amateur astronomy. “You can usually see the ring around Saturn, but with an edge-on view, your hair looks like a thin line of light lying around.”
Over the last few months, Saturn’s vast rings have gradually appeared thinner when viewed through a ground-based telescope. By Sunday, the ring will reach its exact edge-on angle.
The illusion is temporary and lasts only a day or two before the ring slowly appears in vision again.
Events are relatively rare. Ring plane crossing – as the phenomenon is known – usually occurs twice during 29.4 years. This means that it can be seen from the Earth once every 13-15 years.
But unfortunately, Saturn is too close to the sun to see what Skywatcher looks like without the ring this weekend. However, another opportunity this year will be the ring will almost be edge-on on November 23rd later this year (not exactly).
Walker said he used a backyard telescope to witness the intersection of the ring plane in 1995.
“It was great,” he said. “It looked like another planet. I spent most of the night just drinking in that view.”
He said at the time he had only just begun to become interested in astronomy.
In addition to being a quirky product of geometry, the ring plane crossing occurs due to the structure of Saturn’s ring rings. The iconic accessory consists of billions of swirling rocks and ice blocks, but is relatively flat, making it appear that the ring disappears into thin lines when tilted to the earth.
Edge-on views also make Saturn’s moon more visible, Walker said.
“When there is an intersection of these ring planes, the light that normally reflects the ring of Saturn is no longer glancing towards Earth,” he said. “That means we can detect more small moons.”
Walker said that with a regular backyard telescope, people often can find four to six months around Saturn. People may be able to detect almost 12 people during the ring plane traversing the dark sky.
“The really faint things are on the near perfect line, so it becomes clear,” he said.
After this weekend’s Ring Plain intersection, the next complete will take place in 2038. The event, according to Walker, should be visible to Earth.
“I want to see it again,” he said. “I’ll wait a little bit.”
Source: www.nbcnews.com