Observatorio ARVAL


Classic Satellites of the Solar System:

 Planet   Satellite   Magnitude 
 Visual (Vo) 
 Orbital Period 
(days)
 Average Distance 
(MM Km)
 Discovered 
Earth Moon -12.74 27.32 0.384 -
Mars Phobos 11.3 0.32 0.009 1877, A. Hall
Mars Deimos 12.4 1.26 0.023 1877, A. Hall
Jupiter Amalthea 14.1 0.5 0.181 1892, E. Barnard
Jupiter Io 5.02 1.77 0.42 1610, Galileo
- S. Marius
Jupiter Europa 5.29 3.55 0.67 1610, Galileo
- S. Marius
Jupiter Ganymede 4.61 7.15 1.07 1610, Galileo
- S. Marius
Jupiter Callisto 5.65 16.69 1.88 1610, Galileo
- S. Marius
 Planet   Satellite   Magnitude 
 Visual (Vo) 
 Orbital Period 
(days)
 Average Distance 
(MM Km)
 Discovered 
Saturn Mimas 12.9 9.42 0.186 1789, W. Herschel
Saturn Enceladus 11.7 1.37 0.238 1789, W. Herschel
Saturn Tethys 10.2 1.89 0.295 1684, G.D. Cassini
Saturn Dione 10.4 2.74 0.377 1684, G.D. Cassini
Saturn Rhea 10 4.52 0.527 1672, G.D. Cassini
Saturn Titan 8.28 15.94 1.22 1655, C. Huygens
Saturn Hyperion 14.19 21.28 1.481 1848, W.C. Bond
Saturn Iapetus 10.2-11.9 79.33 3.561 1671, G.D. Cassini
Saturn Phoebe 16.45 -550.48 12.952 1898, W.H. Pickering
Uranus Miranda 16.3 1.41 0.130 1948, G. Kuiper
Uranus Ariel 14.16 2.52 0.191 1851, W. Lassell
Uranus Umbriel 14.81 4.14 0.266 1851, W. Lassell
Uranus Titania 13.73 8.71 0.436 1787, W. Herschel
Uranus Oberon 13.94 13.46 0.583 1787, W. Herschel
Neptune Triton 13.47 -5.88 0.355 1846, W. Lassell
Neptune Nereid 18.7 360.14 5.513 1949, G. Kuiper
Pluto Charon 16.8 6.387 0.02 1978, J.W. Christy
 Planet   Satellite   Magnitude 
 Visual (Vo) 
 Orbital Period 
(days)
 Average Distance 
(MM Km)
 Discovered 


The "Classic" satellites were discovered by visual observations from the Earth, all before the 20th century. In 1892 Edward Barnard found Amalthea, the last satellite discovered visually.

The Visual Magnitude (Vo) shown in this table is reached when the planet is in a favorable opposition.

This table, for reasons of relevance, includes 3 satellites with magnitude beyond 15 (Miranda, Nereida and Charon) discovered photographically in the 20th century (in italics).
Many more satellites were discovered in the 20th century by means of super-telescopes and space probes.

The Satellites are ordered according to their Average Distances to their respective planets.


Earth:
The Moon was first observed to have dark plains, brighter mountains, and be marked by craters, by Galileo in the 17th century.
See The Moon, Royal Greenwich Observatory, in ARVAL. See Moon Map, in ARVAL.

Mars:
Neither of its two satellites is visible with small telescopes because they orbit too close to the planet.

Jupiter:
Io, Europa, Ganymede and Callisto were independently discovered in January 1610 by Galileo Galilei and Simon Marius. Their names are those given by Simon Marius by suggestion of Johannes Kepler.
Based on this discovery, Galileo supported the Copernican system as the correct model for the Solar System.
The 4 bright Galilean satellites are easily visible with small telescopes.
Amalthea is not visible with small telescopes due to its low brightness.
See Chasing the Moons of Jupiter, Sky & Telescope. This article includes a Javascript utility to identify Jupiter's 4 brightest moons.
"Mutual" eclipses and occultations (between the Galilean Satellites of Jupiter) are visible only when the Earth is near the orbital plane of the satellites, every 6 years. The last season started on October 2002 and ended on September 2003. The next will be in November 2014, March 2021, and October 2026.
In 1676 the Danish astronomer Ole Romer was able to make the first accurate measurement of the speed of light by using eclipse timings of the Galilean satellites in Jupiter's shadow.
It is generally possible to observe the orbital movements of the satellites in the course of a few hours.

Saturn:
At least Titan, its brightest satellite, is visible with small telescopes.
And possibly Rhea, which follows in brightness. Then possibly Tethys, and Dione.
And in favorable conditions, Iapetus, possibly Enceladus.
Iapetus is locked to Saturn, like the Moon is to the Earth. It is visible when it is to the West of Saturn, with its brightest hemisphere towards the Earth.
Hyperion and Phoebe are not visible with small telescopes due to their low brightness.
Phoebe's orbital period is retrograde, contrary to the rotation of the planet.
See Seeking Saturn's Moons, Sky & Telescope. This article includes a Javascript utility to identify Saturn's 4 brightest moons.

Uranus:
None of its satellites are visible with small telescopes due to their low brightness.
Miranda was discovered on photographic plates.
See ARVAL - Occultation of SAO 164538 by Titania, Sep 7 '01, in ARVAL.

Neptune:
None of its satellites are visible with small telescopes due to their low brightness.
Nereid was discovered on photographic plates.
Triton's orbital period is retrograde, contrary to the rotation of the planet.

Pluto:
Pluto is not visible with small telescopes due to its low brightness.
Charon is not visible with small telescopes due to its low brightness, it was discovered on photographic plates.
Charon is not really a satellite of Pluto; It is so big that they orbit a barycenter outside of Pluto. The pair are considered to be a double dwarf planet.

Note:
Pluto is now a "dwarf planet" by The IAU definition of "planet" and "dwarf planets" (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.




The Solar System satellites data in this section are from
Views of The Solar System - Sun, Planet and Satellite Data (Calvin J. Hamilton).



This page was updated in: April 15 '07, December 9 '12

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