Coplanarity Between Solar System and the Galaxy

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EXPLANATION OF THE MODEL:

It is not easy to illustrate the position of the Solar System regarding the equatorial plane of our galaxy -the Milky Way. There is a small number of books of Astronomy that illustrate the coplanarity of the Solar System and the galaxy; consequently, we often imagine that the North of Earth is also the north of the galaxy. However, the plane of the Solar System is not coplanar with the plane of the Milky Way because it is tilted almost 90° with respect to the equatorial plane of the galaxy.

The Solar System shows three main motions, each one at a specific speed and with limited alternations:

1. The orbital motion of the Solar System around the center of the galaxy is the wider and faster displacement. The speed of the Solar System orbital motion around the center of the galaxy is 217.215 Km/s. The Solar System completes an orbit around the galaxy center each ~226 million years.

2. The second movement, which is described in most of astronomy books, is an oscillation of the Solar System from north to south and from south to north with respect to the galactic plane. The oscillation “upwards” and “downwards” is mainly established by the gravitational pull exerted by other bodies of the Solar System on the Sun, i.e. planets, asteroids, etc. The speed of this movement is 7 km/s.

3. The third motion is a displacement of the solar system towards and outwards the center of the galaxy. It is also an oscillatory movement that is affected by the gravitational pull of cosmic objects in and out the galaxy that are relatively close to the Solar System. This motion has a speed of 20 Km/s, and it is now on course to the constellation of Hercules.

If we were observing the Solar System from outside, its apparent motion would be a helical motion around the nucleus of the galaxy. (See a diagram about the motions of the Solar System).

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EXPLANATION OF THE MODEL:

The plane of the Solar System is tilted about 90° with the plane of the Galaxy. The Solar System is in the Orion Arm (called also Orion Spur), inner with respect to Perseus Arm.

The orbital motion is represented by the slashed large line. This motion has a speed of 217.215 Km/s, hence the Solar System takes 226 million years to complete one lap around the Galactic Nucleus.

The movement onward-backward the nucleus of the Milky Way is determined by the gravitational pull of the nucleus and the stars situated inner the orbital track of the Solar System and by the gravitational pull of the stars outer from the track of the Solar System. This movement has a speed of 20 Km/s.

The motion upwards-downwards the plane of the galaxy are influenced by the motions of the bodies that constitute the Solar System, including the motions of the Sun. The speed of this movement is 5-7 Km/s and comprehends about 20 light years.

The helical blue slashed line represents the apparent motion if we sum the three motions of the Solar System.

(See a model about the motions of the Solar System and the encounter of the Solar System with interstellar clouds of high cosmic radiation).

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EXPLANATION OF THE ILLUSTRATION:

The orbital motion of the Solar System is represented by the yellow slashed line. The Solar System moves at 217.215 Km/s around the Galactic Nucleus.

The Cosmic Cloud is situated up and ahead the Solar System. The Cosmic Cloud is going onwards-backwards the nucleus of the Milky Way at 15-20 Km/s. It is approaching the Solar System at a relative speed of 37 Km/s. We think our Solar System will encounter the cloud at any moment in the next years. Right now, we are experiencing some large “puffs” of dust and cosmic radiation, but those are not part of the main cloud.

THE MOTION OF THE COSMIC CLOUDS AND THE INTERSTELLAR MATERIAL THAT FORM THE ARMS OF THE GALAXY ARE QUITE APART FROM THE MOVEMENTS OF THE STARS THAT ARE ORIGINATED IN THOSE CLOUDS.

There are other bulky "bubbles" of Cosmic Radiation (Interstellar Wind) which will encounter the Solar Wind and probably will cause changes of solar activity which could cause severe climate changes on some planets of the Solar System. The starships Voyager-1 and Voyager-2 have detected high densities of Cosmic Radiation that are affecting the climate of the Earth and of other planets of the Solar System. Such changes are mostly noticeable as greater-than-standard fluctuations of Earth’s tropospheric temperature. Warming and climate change have been detected not only on Earth, but also in Venus, Mars, Jupiter, Saturn, Uranus and Pluto. Some satellites of Jupiter and Saturn are experiencing global warming and climate change, for example Titan.

Nasif Nahle

Biologist

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BIBLIOGRAPHY

E. C. Stone et all. Voyager Explores the Termination Shock Region and the Heliosheat Beyond. Science; Vol. 309, pages 2017 - 2020. 23. September 2005.

Maoz, Dan. Astrophysics in a Nutshell. 2007. Princeton University Press, Princeton, NJ. Pp. 140-147

R. B. Decker et all. Voyager 1 in the Foreshock, Termination Shock, and Heliosheat. Science; Vol. 309, pp 2020-2024. 23 September, 2005.

Shu, Frank H. The Physical Universe: An Introduction to Astronomy. 1982. University Science Books. Sausalito, CA.

Vidal-Madjar, A.; Laurent, C.; Bruston, P.; Audouze, J. Is the Solar System Entering a Nearby Interstellar Cosmic Cloud? The Astrophysical Journal. Vol. 223; pp. 589-600. July 15, 1978. Website: http://adsabs.harvard.edu. Last reading on December 05, 2006.

Brecher, Kenneth. Galaxy. World Book Online Reference Center. 2005. World Book, Inc.

http://www.worldbookonline.com/wb/Article?id=ar215080.

http://www.astro.ufl.edu/~vicki/AST3019/MilkyWay.ppt

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