Starship Asterisk*

Saturn at Opposition

Explanation: Telescopic observers on Earth have been treated to spectacular views of Saturn lately as the ringed planet reached its 2015 opposition on May 23 at 0200 UT. Of course opposition means opposite the Sun in Earth's sky. So near opposition Saturn is up all night, at its closest and brightest for the year. These sharp images taken within hours of the Sun-Earth-Saturn alignment also show the strong brightening of Saturn's rings known as the opposition surge or the Seeliger Effect. Directly illuminated, the ring's icy particles cast no shadows and strongly backscatter sunlight toward planet Earth, creating the dramatic surge in brightness. Saturn currently stands in the sky not far from bright Antares, alpha star of the constellation Scorpius.

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Well, what a difference this is compared with the first ever closeups of Saturn sent back to Earth from Voyager 1. Saturn certainly wasn't at opposition at that time, and the rings looked so dark.

Ann

Dang Awesome!!! Great Job, Christopher.

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Fantastic images, Mister Go! Thank you. Question: what does the IR image indicate that the RGB image does not?

Ann wrote:Well, what a difference this is compared with the first ever closeups of Saturn sent back to Earth from Voyager 1. Saturn certainly wasn't at opposition at that time, and the rings looked so dark.

Ann

Hi Ann. The fact that Saturn wasn't in opposition to Earth in November 1980, when Voyager 1 flew past, had no bearing on the relative brightness of the rings in its images. That depended only on the position of Voyager 1, relative to Saturn and the Sun and on Saturn's axial inclination to the Sun (which was a lot less than at present).

Scorpius, not Sagittarius.

Tex wrote:Scorpius, not Sagittarius.

I went to double check this and it seems to be in Libra!

geckzilla wrote:

Tex wrote:Scorpius, not Sagittarius.

I went to double check this and it seems to be in Libra!

And now I double checked myself to realize that the sentence means Antares is in that constellation, not Saturn.

On the plus side, I just taught myself that the alpha star of Sgr (currently almost 40 degrees from Saturn) is named Rukbat or Alrami, for the knee of the archer.

Nitpicker wrote:Fantastic images, Mister Go! Thank you. Question: what does the IR image indicate that the RGB image does not?

Ann wrote:Well, what a difference this is compared with the first ever closeups of Saturn sent back to Earth from Voyager 1. Saturn certainly wasn't at opposition at that time, and the rings looked so dark.

Ann

Hi Ann. The fact that Saturn wasn't in opposition to Earth in November 1980, when Voyager 1 flew past, had no bearing on the relative brightness of the rings in its images. That depended only on the position of Voyager 1, relative to Saturn and the Sun and on Saturn's axial inclination to the Sun (which was a lot less than at present).

Thanks for that explanation, Nit!

Speaking of Alpha Sagittarii, it's a pale little dot - well, it's brighter than the Sun and it's blue, so that is not so bad. But it is only fourth magnitude.

Ann

Surely the ring particles cast shadows, but they are not visible from earth (right behind the particle from our point of view).

Fantastic job, Chris!

As an average viewer, I would have liked to see an inset showing a series of pictures taken with identical exposure times / filters. The two gorgeous views here force the viewer to read the information and understand that one image is 6 times fainter than the other.

Steve

Antares is the Alpha Scorpii! It's not the alpha star of the constellation Sagittarius, as it is mensioned in today's picture.

HellCat wrote:Fantastic job, Chris!
As an average viewer, I would have liked to see an inset showing a series of pictures taken with identical exposure times / filters. The two gorgeous views here force the viewer to read the information and understand that one image is 6 times fainter than the other.
Steve

Yes.

As presented, one felt as though one were viewing one of those "what is the difference in these two picture" puzzles.

Good on you for figuring out the parenthetical 'min' in the text on the images themselves must be exposure time.

The link on the page to the well remembered and lyrically beautiful Lyrid Shower { http://apod.nasa.gov/apod/ap150423.html } did make up for the otherwise underwhelming - at least, to us great unwashed - presentation of the Seelinger Effect which, as you mention, would have been more striking had identically exposed images also been included.

It's Antares part of Scorpius, rather than Sagittarius?

geckzilla wrote:

geckzilla wrote:

Tex wrote:Scorpius, not Sagittarius.

I went to double check this and it seems to be in Libra!

And now I double checked myself to realize that the sentence means Antares is in that constellation, not Saturn.

But Antares in Sagittarius? Antares is Alpha Scorpii...

jalbertt wrote:It's Antares part of Scorpius, rather than Sagittarius?

Yes, Antares is Alpha Scorpii

Clear night scheduled tonight. midnight. no cloud baiting please

ta152h0 wrote:Clear night scheduled tonight. midnight. no cloud baiting please

Wolf,
I would think that you would also be hoping for Clear Skies on Wednesday (full moon)

WCorvi wrote:Surely the ring particles cast shadows, but they are not visible from earth (right behind the particle from our point of view).

Yes, the ring particles do cast shadows. Depending on the orientation, it is possible to see the shadow of the rings on the planet.

BMAONE23 wrote:

ta152h0 wrote:Clear night scheduled tonight. midnight. no cloud baiting please

Wolf,
I would think that you would also be hoping for Clear Skies on Wednesday (full moon)

Clear night. Full moon. Wolf. . Oh my.

when you have lemons, make lemonade. I can always look a the moon and still marvel at how puny we are

clouds, clouds and more clouds

Great shot of the North Pole Hexagon!

As nobody has asked it seems reasonable to assume that their meaning is well-known but as I don't know I would be grateful if someone could please let me know what the 'I: 152 II: 302 III: 298 (42 min)' and the 'IR I: 167 II:316 III: 312 (7min)' mean? (the IR will be Infrared). I'm guessing the 'S: 7-8/10' may be the seeing conditions being 7 to 8 out of 10 (which sounds like that is OK) but what does the 'T: 3-4/5' mean? Thanks for any help . They are nice images of .

I think you better ask him, David. I looked around the site and could find no clues.