Observatorio ARVAL

Caracas, Venezuela. Latitude 10° 30' N, Longitude 66° 50' W (UT - 4 hrs.)


Loops in the Sky: The Movement of the Planets



The Zodiac is the zone of the celestial sphere 8° to each side of the Ecliptic. The paths in the sky of the Sun, the Moon and the planets remain within this zone, all moving normally to the East (Direct Motion).
Occasionally, a planet will present movement to the West (apparent Retrograde Motion).
In the case of an Exterior Planet (Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto), the Retrograde Motion is due to the parallax effect when the Earth catches up with, and passes the planet.
In the case of an Interior Planet (Mercury and Venus), the Retrograde Motion is due to the parallax effect when being on the same side of the Sun as the Earth, the planet catches up with, and passes the Earth.
The change from Direct to Retrograde Motion, combined with the inclination of their orbits, causes the planets to make loops in the sky. These loops occur on each Sidereal Period for the Interior Planets, on each Synodic Period for the Exterior Planets.

The Sidereal Period is the time a planet takes to complete its orbit around the Sun, measured relative to the stars. The Synodic Period is the time a planet takes to complete its orbit around the Sun, measured relative to the Earth.



Mercury

Mercury:

Its Synodic Period is 115.88 days (0.3173 years)
Its Sidereal Period is 87.97 days (0.2408 years)
Its orbital Inclination is 7.004°

Daily positions in the zone of Leo
From July 15 '04 to September 30 '04
From top (West) to bottom (East)
In Retrograde Motion from August 10 '04 to September 2 '04
From bottom (East) to top (West)

In Inferior Conjunction on August 23 '04
In Conjunction with Regulus (Alpha Leonis) on September 10 '04
In Conjunction with Zavijava (Beta Virginis) on September 27 '04

The bluish vertical line is the Ecliptic
(North to the left)



Venus

Venus:

Its Synodic Period is 583.92 days (1.5987 years)
Its Sidereal Period is 224.70 days (0.6152 years)
Its orbital Inclination is 3.394°

Daily positions in the zone of Taurus
From March 29 '04 to November 8 '04
From top (West) to bottom (East)
In Retrograde Motion from May 18 '04 to July 1 '04
From bottom (East) to top (West)

In Conjunction with The Pleiades (M45) on April 3 '04
In Inferior Conjunction (and Solar Transit) on June 8 '04
In Conjunction with Aldebaran (Alpha Tauri) on July 4 '04

The bluish vertical line is the Ecliptic
The gray line is the plane of the Milky Way
(North to the left)



Mars

Mars:

Its Synodic Period is 779.94 days (2.1354 years)
Its Sidereal Period is 686.98 days (1.8809 years)
Its orbital Inclination is 1.85°

Positions every 5 days in the zones of Aries and Taurus
From August 1 '05 to March 15 '06
From top (West) to bottom (East)
In Retrograde Motion from May 12 '04 to July 3 '04
From bottom (East) to top (West)

In Opposition on November 7 '05.
In Conjunction with The Pleiades (M45) on February 17 '06

The bluish vertical line is the Ecliptic
(North to the left)



Jupiter

Jupiter:

Its Synodic Period is 398.99 days (1.0924 years)
Its Sidereal Period is 4,332.6 days (11.8623 years)
Its orbital Inclination is 1.308°

Positions every 5 days in the zone of Virgo
From September 1 '04 to October 21 '05
From top (West) to bottom (East)
In Retrograde Motion from January 29 '05 to May 29 '05
From bottom (East) to top (West)

In Opposition on April 3 '05
In Conjunction with Zavijava (Beta Virginis) on September 12 '04
In Conjunction with Zaniah (Eta Virginis) on October 17 '04
In Conjunction with Porrima (Gamma Virginis) on November 12 '04, on Mayo 11 '05, and on July 5 '05

The bluish vertical line is the Ecliptic
(North to the left)



Saturn

Saturn:

Its Synodic Period is 378.09 days (1.0352 years)
Its Sidereal Period is 10,759.3 days (29.4580 years)
Its orbital Inclination is 2.488°

Positions every 10 days in the zones of Gemini and Cancer
From June 29 '04 to September 12 '05
From top (West) to bottom (East)
In Retrograde Motion from November 6 '04 to March 26 '05
From bottom (East) to top (West)

In Opposition on January 13 '05
In Conjunction with Wasat (Delta Geminorum) on July 30 '05
In Conjunction with Praesepe (M44) on September 12 '05

The bluish vertical line is the Ecliptic
(North to the left)



Uranus

Uranus:

Its Synodic Period is 369.66 days (1.0121 years)
Its Sidereal Period is 30,684.0 days (84.0100 years)
Its orbital Inclination is 0.774°

Positions every 10 days in the zone of Aquarius
From February 1 '04 to March 27 '05
From top (West) to bottom (East)
In Retrograde Motion from June 9 '04 to November 17 '04
From bottom (East) to top (West)

In Opposition on August 27 '04

The bluish vertical line is the Ecliptic
(North to the left)



Neptune

Neptune:

Its Synodic Period is 367.49 days (1.0062 years)
Its Sidereal Period is 60,188.3 days (164.7901 years)
Its orbital Inclination is 1.774°

Positions every 10 days in the zone de Capricornus
From January 1 '04 to March 16 '05
From top (West) to bottom (East)
In Retrograde Motion from May 20 '04 to October 17 '04
From bottom (East) to top (West)

In Opposition on August 5 '04
In Conjunction with Theta Capricorni on March 1 '04, on August 8 '04, and on May 1 '05

The bluish vertical line is the Ecliptic
(North to the left)



Pluto

Pluto:

Its Synodic Period is 366.73 days (1.0041 years)
Its Sidereal Period is 90,777.3 days (248.5400 years)
Its orbital Inclination is 17.148°

Positions every 10 days in the zone of Serpens Caput (East of Ophiuchus)
From November 1 '04 to December 26 '05
From top (West) to bottom (East)
In Retrograde Motion from March 31 '05 to September 7 '05
From bottom (East) to top (West)

In Opposition on June 14 '05
In Conjunction with Xi Serpentis on March 21 '05

(North to the left)




The planet simulations shown in this page
   were made with TheSky from Software Bisque, version 5.
   The scale of the sky for the simulation changes for each planet.



Note:
Pluto is now a "dwarf planet" by The IAU definition of "planet" and "dwarf planets" (IAU 2006 General Assembly, August 24 '06).
See Observatorio ARVAL: Solar System Data.

On 13 September '06 the IAU Minor Planet Center assigned to Pluto the asteroid number 134340.
See IAU Minor Planet Center Circular 8747 (.pdf).



This page was updated in September 15 '06

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