The "ansae" of saturn's rings

[matt]

I just received an e-mail which refered to the "ansae" of Saturn's rings.

What is that?

[DobDobDob (Ron)]

The portion of Saturn's rings on either side of the planet. Ansae is the Latin word for "handles."

[matt]

Thanks, Ron.

But why not just call them "the rings" and leave it at that?

[DobDobDob (Ron)]

Er...why not just call it a lot of space ice blocks held together gravitationally around a gaseous planet

[matt]

yeah. sounds good to me.

[astroron (Ron)]

It goes back to when the planet was first discovered.
With the first telescopes which were not as good as todays they looked like handles protruding from each side of the disc.
It was left to Christian Huygens to identify them as rings.

[AJames]

The Sources of "Ansae" is a follows;

The rings were first seen by Galileo in 1610, who did not know what they really were. He said all that he could see were two spherical balls near the main disk - an illusion created by the telescope's very poor quality. Later he described them as ansae, which translates to mean literally handles.

"I have observed the highest planet to be tripled-bodied. This is to say that to my very great amazement Saturn was seen to me to be not a single star, but three together, which almost touch each other."

Even more puzzling for Galileo was that they had all but vanished in 1612 only to return again in 1615. It was only until decades later in 1655 that Hugyens first realised they were true rings encircling the planet. This result appeared in his "Systema Saturnium", which was first published in 1659, saying;

"Saturn is surrounded by a thin flat ring not touching it anywhere, which is oblique to the ecliptic."

Looking at the earlier observations he soon knew that the disappearance of the rings was due to the changing aspects of Saturn with the rings being tilted to the plane of the ecliptic.

The Rings of Saturn are invisible to the naked-eye but are prominent in telescopes as small as 3cm. They are about 272 000 km across being 2.2 times the size of the main disk and appear less yellowish than the planet's main disk.

These rings are not solid disk, as the first telescopic astronomers thought.

[matt]

Thanks, folks.

Very thorough explanation

[AJames]

Saturn is not the only object to display ansae, as these features are common place in planetary nebula.

It is one of the most obvious structural properties or features among the planetary nebula and the bipolar planetaries are the ansae (singular; ansa), which in some ways look like ‘handles’.

It is often suggested to be caused by the phenomenon of multiple ejection of material from the central white dwarf star. Primarily, the shape and brightness variations are manifest by this star - often being a close binary or possibly even large planetary bodies.

Theoretically, the existence of such binaries would actually influence the flow of the nebulosity away from the nebulae, producing variations in torque/ angular momentum. In turn, this precesses the material into spirals, such as seen is commonplace southern planetaries like:-

NGC 3918 (The Blue Planetary) in Centaurus, NGC 5189 (The Spiral Planetary)/ NGC 4071 / MyCn18 [All in Musca]

These examples all have produced multiple groups ansae as seen within the imaged nebulosity.

Current understand of these mechanisms has lead to the production of multitudes of computer-generated planetaries - ans some explaination of planetary formation and gas outflows.

[Ric]

A very interesting read, I never knew about the rings official name.
It is said that you should learn something new everyday and that was today's.

Cheers

[CosMos (Rich)]

Not forgetting the "Saturn Nebula" in Aquarius (NGC 7009) with its ansae.