Zodiac Constellations on Planetary Plane

[Vartigy]

Hi all,

Just using my updated version of Distant Suns Lite (iPod astro app) and I noticed that all 12 constellations of the zodiacs are positioned approximately along the plane on which out solar system planets move about on.

Has anyone else noticed this?
And does anyone know why these 12 significant constellations are so related to our planetary alignment?

[M54 (Molly)]

I think that it's most probable that because they happen to fall within the plane of the ecliptic that they were chosen as the zodiac signs.

[iceman (Mike)]

As Molly says..

The planetary plane = the ecliptic, which is a result of how our solar system was formed.

The zodiac constellations were chosen BECAUSE they lie on the ecliptic.

[Vartigy]

Ahh ok.
Are those regions of the sky more viewable than others all year round?
I'm just wondering what the physical significance is, besides the fact they lie on the ecliptic (thanks for that smidge of info btw guys)

Sorry if this all seems a dumb question.

And on another note.
Besides the astrology significance... is there a physical significance to them? Perhaps are/were they used for navigational purposes?

[Coen]

Current best understanding is that when the gas cloud collapsed it eventually formed a spinning mostly flat gas disk. This is turn coalesced into lumps which eventually became our Sun (in the middle) and planets (in orbits sweeping paths clean) all in the approximate plane of the original flat disk. Thus all the major planets have orbits whose inclinations relative to each other are small. By definition the inclination of the Earth's orbit is zero and as we go around the Sun, the Sun appears to trace a path across the sky that is called the ecliptic. Each of the planets is slightly inclined to this line oscillating either side of it. We in turn have an axial tilt with respect to the ecliptic which gives the seasons and the northern/southern extents of the ecliptic.

Those watching the heavens could not help but notice the path of the Sun against the background stars and carved up the sky into constellations with particular significance for the those that the Sun and planets appeared to wander through. Thus approximately each month (12 of them) timeframe that the Sun spent in a region got a constellation so 12 Zodiac constellations or houses for the Sun.

Since that was set-up (2000+ years ago), we now have standardised constellation boundaries coupled with the Earth's precession gives the result that the first point of Aries is no longer in Aries and there are technically 13 constellations that the Sun spends time in.

As far as I know there is no particular significance to the Zodiacal constellations as compared to others beyond the facts listed above; navigation is based on known bright stars and timings not on constellations.

[Dennis]

In our annual journey around the Sun, during each month the Sun “appears” to be “in” each of the 12 signs of the zodiac for approximately 1 month when viewed from the Earth.

These Zodiacal signs lie on the plane of the Ecliptic which is why the Sun can never “appear” to be in, say Ursa Major, Crux, etc as these constellations lie further N or S of the Ecliptic.

Same with the Moon; you will not see the Moon in the constellations of say, Sculptor or Lynx.

Cheers

Dennis

[Virgs]

The Sun appears in 13 constellations not 12, you have missed Ophuichus and in no way does it spend nearly one month in each.
Here are the days it spends in each
Aries 25.5
Taurus 38.2
Gemini 29.3
Cancer 21.1
Leo 36.9
Virgo 44.5
Libra 21.1
Scorpius 8.9
Ophiuchus 18.4
Saggitarius 33.6
Capricornus 27.4
Aquarius 23.9
Pisces 37.7
If you think about it, it makes sense as the constellations are different sizes.
People think wrongly there are 12 and the one month rule applies because of all that astrology crap printed in daily news papers. Dont be one of them and use the above information.

[Jarvamundo (Alex)]

Virgs thats the post of the year... well put.... haha

[Virgs]

Thanks, glad it is appreciated!

[Blue Skies (Jacquie)]

The zodiac constellations were seasonal markers. They weren't created all at once, but in groups of 4 over thousands of years. They marked the 4 turning points in the year, the solstices and the equinoxes. The oldest constellations are the largest, the youngest the smallest. You'll also notice there is a group of three that pertain to watery things - these marked the winter solstices, often the rainy season in Mediterranean climes. Taurus is strongly linked to the spring equinox in Babylonian/Mesopotamian times when the Bull was seen as a sign of strength and fertility. There is a good article on the creation of the zodiac in an old Sky & Telescope article "When the Zodiac Climbed into the Sky" by Alexander Gurshtein, October 1995, pg 28-33.

And please remember the modern day constellations had their boundaries fixed and agreed upon in 1930. Before then constellation boundaries were vague and up to the individual uranographer to draw in. The ancient constellations were symbols and markers. Trying to compare the ancient systems to today's modern system is like comparing apples to oranges. All this argument about how long the sun spends in each and whether there are 12 or 13 or more zodiac constellations is wasted space and time in my opinion.

[Vartigy]

Interesting read. Thanks to all whom responded. Beginning to get a clearer picture on this, even though from reading above, there still seems an air of vagueness about this phenomena.