Welcome to Visual Astronomy
Astronomical Observing
Based mainly on observation with binoculars

By Alain Dussault

The Planets (Jupiter, Mars, Venus, Saturn and Mercury

The following two sites will give you intensive descriptions on all planets of our solar system.

The Solar System and the Nine Planets:   http://www.atklab.yorku.ca/tnp/nineplanets/nineplanets.html
Views of the Solar System         http://www.hawastsoc.org/solar/homepage.htm

We are going to see together, the planets that are visible and observable.  We will detailed those that are observable with binoculars and what a telescope add to the observation.

A Windows program on the planets and their phenomena, is "MERIDIAN.ZIP", at the following site.  this program has menus either in French, English or Spanish.


Another program on the planets is "PLTVER41.zip", which you will get at:   http://www.shareware.com

Once there use the search engine.


Jupiter is the biggest planet of our solar system.  With its many satellites, Jupiter reign on a miniature solar system of its own. 

Because of its great dimension and if high albedo, Jupiter can attain a magnitude of -2.6.  It can become as much brilliant than Venus.  Being a far away planet from Earth, Jupiter can be observe in opposition to the Sun, an ideal situation for the observation.

Jupiter is the most interesting planet to observe with binoculars, due in particular to its great dimension and also to its main four brilliant satellites.  In binoculars, we see distinctly a disk, if we mount the binoculars on a tripod or old them on a rigid post.  In bonus we can also observe its four principal satellites with binoculars.  These satellites are; Io, Europa, Ganymede and Callisto.

As Jupiter make a complete rotation in 9 hr 56 min, it is very interesting to observe it, on many consecutive nights, because its four satellites move rapidely around it. They are not called the dancing satellites of Jupiter for nothing.

As these satellites turn in the axis of rotation of Jupiter, they are almost always in a straight line.  One night, all of them will be seen on one or the other side of the planet.  Another night distributed evenly on each side, and so on.  At other times some won't be visible because they will be passing in front or in the back of Jupiter or being eclipse by another one. 

In a telescope, you will be able to see shaded bands on the surface of the planet.  With at least an 8", you will be able to observe the Great Red Spot.  Moreover, if a satellite pass in from of Jupiter, it will be visible.  Or you will be able to see the shadow of a satellite projected on the surface of the planet.

The satellites events on Jupiter are so numerous and accessible, that Sky & Telescope publish them regularly.  The satellites position with Jupiter are shown graphically and also there are table of satellites events.

A DOS program "JUPSAT.ZIP", calculated the position of the satellites for a given date and time". You can get it at:


Also many recent update of software do it too, like; Atlas du Ciel, Meridian, Guide 6 et others.


Mars is very interesting to watch because of its distinctive reddish color, visible to the naked eyes.  the eccentricity of its orbit is such, that it approach up to 56 millions of kilometers from the Earth at every 17 years.  Mars is in opposition every 780 days, that is the reason why it is visible about every two years.  Its magnitude vary form -1 to  -2.8.

In binoculars, we distinguish better its reddish color and see also a disk.  With a telescope, when it is nearer the Earth, we can see some features on its surface and also the polar region.


At certain times, Venus is the most brilliant object in the sky.  It is surname the morning or night star. Its magnitude can be up to -4.

As mercury, its orbit is between the Sun and the Earth.  In consequence, its pass by different phases, like the Moon.  It is interesting to follow this phenomena.  Curiously, when it is most brilliant, it is in it first stage of phase, we then see a crescent.  But when it is less brilliant, we see a complete disk.


Saturn (120,000 km in dia.) is more far away from us than jupiter, and though its diameter est almost as great as Jupiter  (143,000 km), it is less brilliant.  But the external diameter of its rings is 274,000 km.

In binoculars Saturn present an ellipse like form, due to its rings, which cannot be resolute with this instrument.  At certain time, its rings are not visible, they open and close in time.

But with a telescope, we can easily distinguish its rings, and with a 8" telescope, some of its satellites like, Titan, Rhea, Iapetus, Dione and Tethys.  I must say that it s more difficult to observe them, because they are not much brilliant and are easily confuse with nearby stars and the orbits are much greater from the planet then is the case for Jupiter.

In a telescope, you can see the Cassini division, this black band that seem to separate the ring in two. Certain DOS programs, will graphically show Saturn satellite positions, they are "SATVIEW2.ZIP" and "SATSAT1.ZIP", which you can get at:



Mercury is the smallest planet of our solar system and also the nearer to the Sun.  To the naked eyes, Mercury can be seen as a luminous point for about half an hour, just after the Sun as set or just before it  has rise, and only at certain time of the year.  This planet is then always near the horizon and is not easy to observe.  You need an horizon free form obstacle.  

Next chapter, Deep Sky or Celestial Objects. Definition of different objects

Preceding chapter, The Moon, the Sun and the Spring and Summer Constellations

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Last update August 1st, 1999.