Starship Asterisk*

[quote="Rusty Brown in Cda"]I'm mystified: if Venus and Jupiter define the ecliptic in this picture, then the sun must be setting almost horizontally, or not even setting at all, as at the north pole in summer.
Can anyone offer enlightenment?[/quote]
Neither Venus nor Jupiter define the ecliptic. The ecliptic is defined by the plane of Earth's orbit around the Sun. Jupiter does not lie on that plane- its orbit is tipped by 1.3°. Venus does not lie on that plane, either- its orbit is tipped by 3.4°. So depending on where each planet is on its orbit, we see it deviate from the ecliptic. Of course, if all the planets actually orbited on a common plane we wouldn't just have regular conjunctions, but regular transits- events that are very rare indeed.

[attachment=0]ecliptic.png[/attachment]

I'm mystified: if Venus and Jupiter define the ecliptic in this picture, then the sun must be setting almost horizontally, or not even setting at all, as at the north pole in summer.
Can anyone offer enlightenment?

[quote="quigley"]Is Mars not visible in this shot due to the morning light?

And please, what DOES back to front mean?[/quote]
Don't forget, this image is a Sunday repeat from 2005 and doesn't represent the current configuration

[quote="quigley"]Is Mars not visible in this shot due to the morning light?[/quote]
This image was made in the evening, just past sunset. Mars rose on the opposite side of the sky about three hours later.

Is Mars not visible in this shot due to the morning light?

And please, what DOES back to front mean?

[quote="keithastro"]The picture is back to front.[/quote]
What does that mean? Some kind of mirror image? The picture is geometrically correct, showing the actual appearance of the western evening sky on 6 September 2005.

The picture is back to front.

[quote="bystander"]Earth is visible. Earth is a planet.[/quote]
Si.

Howsomeever, when one saw the sky this past week, it was Jupiter, Venus and Mars which were visually close to one another - so it is not clear why Luna, Spica, Jupiter and Venus can count as "the same" quadrangle.

The (re)selection of this photo for APOD does mind one of the practice of sharing photos of one's most remarkable baby ... and one does accept it with the same patience, as APOD remains my favourite website.

Earth is visible. Earth is a planet.

You mention 3 planets are visable in the picture but only identify two (Venus and Jupiter). Did you mean to only mention 2 or was Spica misidentified?

Thanks,
Doc Savage

[url=http://apod.nasa.gov/apod/ap151108.html][img]http://apod.nasa.gov/apod/calendar/S_151108.jpg[/img] [size=150]A Quadruple Sky Over Great Salt Lake[/size][/url]

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