APOD: Cassini Spacecraft Crosses Saturn's... (2019 Dec 29)

[APOD Robot]

Cassini Spacecraft Crosses Saturn's Ring Plane

Explanation: If this is Saturn, where are the rings? When Saturn's "appendages" disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear. This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade. In modern times, the robot Cassini spacecraft orbiting Saturn frequently crossed Saturn's ring plane during its mission to Saturn, from 2004 to 2017. A series of plane crossing images from 2005 February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro. Pictured here, digitally cropped and set in representative colors, is the striking result. Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold. Details of Saturn's rings can be seen in the high dark shadows across the top of this image, taken back in 2005. The moons Dione and Enceladus appear as bumps in the rings.

<< Previous APOD

This Day in APOD

Next APOD >>

[orin stepanek]

Unusal to see the rings in this kind of view!
Gives the picture a bit of starkness!

saturnplane_cassini_1004.jpg (12.31 KiB) Viewed 3416 times

[neufer]

<<Galileo Galilei was the first to observe the rings of Saturn in 1610 using his telescope, but was unable to identify them as such. He wrote to the Duke of Tuscany that "The planet Saturn is not alone, but is composed of three, which almost touch one another and never move nor change with respect to one another. They are arranged in a line parallel to the zodiac, and the middle one (Saturn itself) is about three times the size of the lateral ones." He also described the rings as Saturn's "ears". In 1612 the Earth passed through the plane of the rings and they became invisible. Mystified, Galileo remarked "I do not know what to say in a case so surprising, so unlooked for and so novel." He mused, "Has Saturn swallowed his children?" — referring to the myth of the Titan Saturn devouring his offspring to forestall the prophecy of them overthrowing him. He was further confused when the rings again became visible in 1613.

Early astronomers used anagrams as a form of commitment scheme to lay claim to new discoveries before their results were ready for publication. Galileo used smaismrmilmepoetaleumibunenugttauiras for Altissimum planetam tergeminum observavi ("I have observed the most distant planet to have a triple form") for discovering the rings of Saturn.>>

[Ann]

Let's hope that razor-sharp "wire trap" doesn't cut Saturn in half!

Click to play embedded YouTube video.

Ann

[HunterofPhotons]

Why does Saturn's upper pole appear at the one o'clock position and it's bottom pole is shown to be at the six o'clock position? I've never seen this before.

dan kowall

[Chris Peterson]

Why does Saturn's upper pole appear at the one o'clock position and it's bottom pole is shown to be at the six o'clock position? I've never seen this before.

Keep in mind that the rings have zero inclination with respect to Saturn (that is, they are perfectly perpendicular to Saturn's rotation axis). Saturn's poles in this image are exactly at 12 and 6 o'clock. You're being fooled into seeing the upper pole where you are by the shadow of the rings, which are not concentric around the poles.

[neufer]

Photomontage of Saturn with a false-colour image of ultraviolet aurora taken with the Imaging Spectrograph on January 24 superimposed on an image of visible light taken with the Advanced Camera for Surveys on March 22, 2004 from NASA's Hubble Space Telescope

---

Why does Saturn's upper pole appear at the one o'clock position and it's bottom pole is shown to be at the six o'clock position? I've never seen this before.

Keep in mind that the rings have zero inclination with respect to Saturn (that is, they are perfectly perpendicular to Saturn's rotation axis). Saturn's poles in this image are exactly at 12 and 6 o'clock. You're being fooled into seeing the upper pole where you are by the shadow of the rings, which are not concentric around the poles.

From Earth, Saturn is almost perfectly backlit (by the Sun).

Saturn's shadow on its rings is somewhat discernible but the
ring shadow on Saturn is well hidden by the rings themselves.

• But I was thinking of a plan
  To dye one's whiskers green,
  And always use so large a fan
  That they could not be seen.

[Ann]

From Earth, Saturn is almost perfectly backlit (by the Sun).

Saturn's shadow on its rings is somewhat discernible but the
ring shadow on Saturn is well hidden by the rings themselves.

I googled "Backlit Saturn" and got this:

Click to view full size image

And it is not what Saturn looks like from the Earth!

• But I was thinking of a plan
  To dye one's whiskers green,
  And always use so large a fan
  That they could not be seen.

Green eyed Cat.png (272.08 KiB) Viewed 3297 times

I like your poem, though. Who wrote it?

I wanted to post a picture of a green-whiskered cat, but I couldn't find one. This green-eyed cat-purse is nice, though.

Ann

[neufer]

From Earth, Saturn is almost perfectly backlit (by the Sun).

Saturn's shadow on its rings is somewhat discernible but the
ring shadow on Saturn is well hidden by the rings themselves.

I googled "Backlit Saturn" ...

I'm afraid I misused the term "Backlit" ... but you get the idea.
https://www.rhymezone.com/r/rhyme.cgi?W ... 2=l&org3=y
https://www.rhymezone.com/r/rhyme.cgi?W ... 2=l&org3=y

I like your poem, though. Who wrote it?

Click to play embedded YouTube video.

The White Knight explains to Ann a confusing nomenclature for the song.

‘You are sad,’ the Knight said in an anxious tone: ‘let me sing you a song to comfort you.’

‘Is it very long?’ Ann asked, for she had heard a good deal of poetry that day.

‘It’s long,’ said the Knight, ‘but very, VERY beautiful. Everybody that hears me sing it--either it brings the TEARS into their eyes, or else--’

‘Or else what?’ said Ann, for the Knight had made a sudden pause.

‘Or else it doesn’t, you know. The name of the song is called “HADDOCKS’ EYES.”’

‘Oh, that’s the name of the song, is it?’ Ann said, trying to feel interested.

‘No, you don’t understand,’ the Knight said, looking a little vexed. ‘That’s what the name is CALLED. The name really IS “THE AGED AGED MAN.”’

‘Then I ought to have said “That’s what the SONG is called”?’ Ann corrected herself.

‘No, you oughtn’t: that’s quite another thing! The SONG is called “WAYS AND MEANS”: but that’s only what it’s CALLED, you know!’

‘Well, what IS the song, then?’ said Ann, who was by this time completely bewildered.

‘I was coming to that,’ the Knight said. ‘The song really IS “A-SITTING ON A GATE”: and the tune’s my own invention.’

[orin stepanek]

[/quote]

Green eyed Cat.png

I like your poem, though. Who wrote it?

I wanted to post a picture of a green-whiskered cat, but I couldn't find one. This green-eyed cat-purse is nice, though.

Ann
[/quote]


I never seen a green whiskered cat; but when I was a kid Mom took me to a movie called the boy with green hair!

https://video.search.yahoo.com/yhs/sear ... tion=click

[Ann]

https://www.rhymezone.com/r/rhyme.cgi?W ... 2=l&org3=y
https://www.rhymezone.com/r/rhyme.cgi?W ... 2=l&org3=y

I like your poem, though. Who wrote it?

Click to play embedded YouTube video.

The White Knight explains to Ann a confusing nomenclature for the song.

‘You are sad,’ the Knight said in an anxious tone: ‘let me sing you a song to comfort you.’

‘Is it very long?’ Ann asked, for she had heard a good deal of poetry that day.

‘It’s long,’ said the Knight, ‘but very, VERY beautiful. Everybody that hears me sing it--either it brings the TEARS into their eyes, or else--’

‘Or else what?’ said Ann, for the Knight had made a sudden pause.

‘Or else it doesn’t, you know. The name of the song is called “HADDOCKS’ EYES.”’

‘Oh, that’s the name of the song, is it?’ Ann said, trying to feel interested.

‘No, you don’t understand,’ the Knight said, looking a little vexed. ‘That’s what the name is CALLED. The name really IS “THE AGED AGED MAN.”’

‘Then I ought to have said “That’s what the SONG is called”?’ Ann corrected herself.

‘No, you oughtn’t: that’s quite another thing! The SONG is called “WAYS AND MEANS”: but that’s only what it’s CALLED, you know!’

‘Well, what IS the song, then?’ said Ann, who was by this time completely bewildered.

‘I was coming to that,’ the Knight said. ‘The song really IS “A-SITTING ON A GATE”: and the tune’s my own invention.’

"Oh freddled gruntbuggly,

Thy micturations are to me

As plurdled gabbleblotchits on a lurgid bee.

Groop, I implore thee, my foonting turlingdromes,

And hooptiously drangle me with crinkly bindlewurdles,

Or I will rend thee in the gobberwarts

With my blurglecruncheon, see if I don't!"


(But you were nicer to me. At least you didn't torture me with your poem!)


Ann

[neufer]

Click to play embedded YouTube video.

"Oh freddled gruntbuggly,
Thy micturations are to me
As plurdled gabbleblotchits on a lurgid bee.
Groop, I implore thee, my foonting turlingdromes,
And hooptiously drangle me with crinkly bindlewurdles,
Or I will rend thee in the gobberwarts
With my blurglecruncheon, see if I don't!"

(But you were nicer to me.
At least you didn't torture me with your poem!)

I quite liked it really. The imagery was really particularly affective and the metaphysical prop…

Art Dent