I have an app on my iPod Touch that lets you view where the planets are. So in the afternoon, I pointed it west, and it showed me that all the planets were on the west-east line, either below or above the horizon. I know that all planets rise in the east and set in the west, but do they all have to be on the exact/close to the east-west line. If this is rare, I would be interested in knowing. Thank you.
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Just about everything appears to rise in the east and sets in the west.
This has nothing to do with the objects themselves. This is due to Earth rotating (CCW as viewed from North), hence by definition, the eastern horizon is sinking and the western horizon is rising, making it appear as if the celestial bodies rise in the east and set in the west.
The UNUSUAL examples are those that rise in the west and set in the east. Those are the retrograde orbits...of which none of the planets have.
The only retrograde orbit we think we see is just apparent retrograde, whereby Earth passes an outer planet up on the inside track. The most interesting apparent retrograde is Mars in opposition, which goes backwards through the constellations for several months.
Nothing really *needs to* be rising or setting at exactly the east or west line. That is a characteristic of it being spring time, about a month post equinox. On either equinox, the sun rises and sets with exact east-west lines.
The planets aren't substantially inclined, so they sort of follow the same path as the sun. We call this path...the ecliptic.
Of the bodies officially called planets, Mercury is the most inclined at about 7 degrees off ecliptic. Contrast this with the Moon being inclined about 5 degrees.
This has nothing to do with the objects themselves. This is due to Earth rotating (CCW as viewed from North), hence by definition, the eastern horizon is sinking and the western horizon is rising, making it appear as if the celestial bodies rise in the east and set in the west.
The UNUSUAL examples are those that rise in the west and set in the east. Those are the retrograde orbits...of which none of the planets have.
The only retrograde orbit we think we see is just apparent retrograde, whereby Earth passes an outer planet up on the inside track. The most interesting apparent retrograde is Mars in opposition, which goes backwards through the constellations for several months.
Nothing really *needs to* be rising or setting at exactly the east or west line. That is a characteristic of it being spring time, about a month post equinox. On either equinox, the sun rises and sets with exact east-west lines.
The planets aren't substantially inclined, so they sort of follow the same path as the sun. We call this path...the ecliptic.
Of the bodies officially called planets, Mercury is the most inclined at about 7 degrees off ecliptic. Contrast this with the Moon being inclined about 5 degrees.
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They will rise is the east and set west, but not exactly due east and due west since all the planets are at a different inclinations with respect to the sun. Meaning that if the sun was at the center of a sheet of paper and the earth was in the plane of the paper, some of the planets would be above the paper and some would be below.
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