"[T]his cosmic history is the
backbone of Steiner’s work.”
— Gary Lachman
Let's step back to consider some of the beliefs that lie behind the Waldorf curriculum. These beliefs are usually not spelled out, explicitly, in Waldorf classes. (Although, sometimes, they are.)
Steiner taught that thus far we humans have passed through three major stages of evolution, which he called “Old Saturn,” “Old Sun”, and “Old Moon.”  The connection between these ancient "planetary conditions" and the present-day members of our solar system called Saturn, Sun, and Moon is not always crystal clear, but with a little work we can generally figure it out.
In some instances, Steiner said, the present members of the solar system (planets: places in the sky) are evolutionary descendants or antecedents of their namesakes (planetary conditions: periods of time). Thus, the planet Saturn as we see it now is a remnant of the planetary condition called Old Saturn — Saturn is a reincarnation of Old Saturn within today's more highly evolved solar system. The planet Venus, on the other hand, is a preview of the planetary condition that will exist after our present Earth stage of evolution comes to an end: The planet Venus prefigures the Future Venus planetary condition (Future Venus: the stage of cosmic evolution that will come after the present stage ends).
In brief, Steiner's basic account of at least some of the planets in our current system is this: Today's planets are manifestations, with variations, of evolutionary states that have happened or will happen.
But Steiner sometimes also gave differing accounts, which either supplement or contradict his basic account. By one of his other accounts, for instance, he said that Venus is a husk tossed off by Lucifer. “Lucifer himself takes part in Earth evolution with the perpetual longing within himself for his true home, for the star Venus ... [W]hat Lucifer casts off as a husk...shines down from heaven as Venus.” 
Venus-as-husk and Venus-as-preview may or may not be compatible concepts. Sometimes we can reconcile Steiner's various statements, sometimes we can't. Steiner described a living, mutating universe in which nothing stays quite the same for long. Everything is in flux. Thus planets evolve, much as humans do: “Now just as man passes through the various stages of his life, as child, young man or woman, old man or woman, so does a planet.”  The mutating nature of reality limits our ability to pin things down in clear, logical categories. At least, this is what Steiner sometimes said. You can decide whether this idea provides sufficient cover for Steiner's tendency to contradict himself.
Let's get back to Steiner's basic account. The entire solar system has evolved, incarnating in a series of progressively more advanced forms. “Old Saturn,” “Old Sun”, and “Old Moon” were stages of this evolution. During Old Saturn, the solar system assumed its first incarnated state, which was very different from its present state. The divine purpose for the evolution of the solar system was to enable humanity to evolve. In this sense, we were always the center of the solar system, in all of its progressive forms. Likewise, the planet that is humanity's home world during physical incarnations, the Earth, was always the center of the solar system. Thus, we can speak of cosmic evolution as the evolution of the Earth itself; in other words, the evolution of the Earth is essentially the same as the evolution of the entire solar system. “Before the Earth became the planet we know, it was a very different one. At the beginning of time it was a planet called, in occult science, [Old] Saturn. Altogether there have been four successive incarnations of the Earth: [Old] Saturn, [Old] Sun, [Old] Moon and [Present] Earth.” 
So the planet Earth as we know it today is, in a sense, the culmination of the previous stages of cosmic evolution. The evolutionary stage in which this planet exists today is called Present Earth: The planet we live on is called Earth; the period we live in is called Present Earth.
If we want to trace the evolution of the planet Earth, we must trace the evolution of the entire solar system. If we want to trace the evolution of other members of today's solar system, we must trace the same general evolution, and this can lead to some complications. Thus, for instance, even though Steiner said that the Earth was once Old Sun, he also said that the Sun was once Old Sun. “Our Sun is a fixed star; the old Sun was a planet [i.e, a planetary condition], and in the course of its incarnations it has worked itself up from the substance and being of a planet [sic] to the rank of a fixed star." 
The key to all this, the master concept that brings general order out of the welter of these statements, is the following: The entire solar system is evolving. And it is doing so for our benefit. Thus, the gods caused the solar system — and ourselves — to come into existence long, long ago. The first incarnation of the solar system is called, in occult science, "Old Saturn." It has been given this name because the forces associated with Saturn were predominant throughout the solar system at that time. So, out of effectively nothing, the solar system came into existence, we along with it. The solar system and humanity evolved a certain amount, then they ceased to exist. They receded again into nothingness, as it were, catching their breaths, as it were. Then the entire solar system reincarnated in a new form, called "Old Sun." Everything in the solar system — including human beings — existed in new configurations then, different from what had existed before and different from what would exist in the future. All of the parts of Old Sun evolved for a while, then all of Old Sun (the solar system) blinked out of existence again. Following another rest period, the entire solar system then reincarnated in a third form, called Old Moon... OK? You get the idea. The solar system is evolving, it reincarnates in differing forms, and all of this is happening for our benefit, so that we can evolve to higher and higher forms. The solar system currently exists in the form we see around us now, with the planets that we see in the sky now, and we are as we are now. This is called the Present Earth stage of evolution. After it blinks out of existence, there will be a rest phase, and then everything in the solar system — including us — will reincarnate in a new condition called Future Jupiter. That condition will later be followed by a rest phase and then an evolutionary stage called Future Venus, which in turn will be followed by a rest phase and then an evolutionary stage called Future Vulcan. Humans who survive into the Future Vulcan stage of existence will be very, very highly evolved — they will be high spiritual beings. [For more on all this, see "Everything" and the essays that follow it.]
Before pressing on, let's blink out of existence for a moment and take a breather.
"[T]his cosmic history is the backbone of Steiner’s work.”
— Gary Lachman, RUDOLF STEINER
(Jeremy P. Tarcher/Penguin, 2007), p. 147.
Ready to press on?
Well, then. Let's return to what interests us most: ourselves.
We human beings lived during each stage of the solar system's evolution, although during the early stages we weren’t recognizably human yet. “Even on the planet Saturn [i.e., during the planetary condition called Old Saturn] man was present [in a different, earlier form].”  During Old Saturn, we did not have the sorts of bodies we have now, nor did we have the minds and consciousness we have now. In fact, we were virtually comatose. We woke up a bit more during Old Sun — we were no longer in a coma-alike stage, just very deeply asleep. During Old Moon, we woke a bit more — our sleep became enlivened by dreams, metaphorically speaking. We are now as awake as we are here on/during Earth — we experience what Steiner sometimes called ordinary waking consciousness. We will wake up far more during our future stages of evolution, rising to progressively higher and higher stages of mystical, clairvoyant awareness.
Steiner knew that his cosmology could be confusing, so he offered clarifications. Thus, as we have seen, Steiner confusingly said that we once lived "on the planet Saturn." But Steiner clarified: This does not mean we lived on the ringed planet we see in the sky today. We have never lived on any planet but Earth: “[W]e must not picture these four planets [i.e., planetary conditions] Saturn, Sun, Moon and Earth [i.e., Old Saturn, Old Sun, Old Moon, and Present Earth] as four separate planets; they are four different conditions of the same planet [Earth] ... Man has never been on any other planet, but the Earth has existed in these four different conditions.”  Each planetary condition was an incarnation of the Earth (or, the entire solar system). Old Saturn was the Earth in one form, Old Sun was the Earth in its second form, and so on. Therefore, we humans have never lived on any planet except the Earth (in its various forms).
This is clear enough, I think. But, unfortunately, Steiner sometimes said something very different. He said, for instance, that at one time during the Present Earth stage of evolution, humans fled to other planets in the solar system. (To follow the following, you should know that, according to Steiner, humans once lived on the lost continent of Lemuria, which they destroyed. They then moved to the lost continent of Atlantis, which they destroyed. Along the way, most humans fled from the Earth to other planets.) Here's how Steiner put it: “You know from the book OCCULT SCIENCE [written by a certain R. Steiner] that during the Lemurian epoch [i.e., when humans lived on Lemuria]...only a few [humans] remained on the earth ... [T]he majority of souls withdrew from the earth to other planets, continuing their life on Mars, Saturn, Venus, Jupiter, and so forth ... [D]uring the Atlantean epoch [i.e., when we lived on Atlantis], these souls gradually came [back] down to earth in order to incarnate in earthly bodies under the changed earthly conditions, and to appear in ever new incarnations.”  [For more on Lemuria and Atlantis, see "Lemuria" and "Atlantis".]
So, as it turns out, humans have indeed lived on other planets. During the Lemurian epoch, most humans left Earth for other planets, and during the Atlantean epoch they returned to Earth. How can we reconcile this highly reliable historical account with Steiner's assurance that "man has never been on any other planet"? Maybe we can, maybe we can't. But setting that issue aside, let's focus on this: The little history we have just learned (most people went to other planets and then returned to Earth) helps explain, Steiner said, why humanity separated into various nations and races. [See "Everything".] The humans who went to Saturn came back having been changed by the spiritual forces of Saturn. Likewise, the humans who went to Mars, Jupiter, etc., came back changed by their experiences there. After they returned to Earth, the humans-who-left-Earth interbred with the humans-who-stayed-on-Earth, and the result was a range of different human types. In other words, thereafter humanity consisted of Earth humans, Saturn humans, Mars humans, etc. Thus, for instance, some of the resulting generations “had their origins in the interbreeding of Earth offspring with humans who...moved to Jupiter. In the sense of spiritual science [i.e., Anthroposophy], we call these the 'Jupiter humans' ... There were also...'Mars humans' ... We can also distinguish 'Saturn humans.'"  [For more on "Jupiter humans," "Mars humans," etc., as well as humanity's overall relationship to various "planets," see "Planetary Humans".]
(Steiner sometimes gave a rather different account of our racial origins, which we might take as the underlying explanation: why things went awry. Steiner sometimes said that humanity divided into races because of the interference of two arch-demons, Lucifer and Ahriman. [See "Universal".] All of humanity should be evolving together at the same rate, and thus all humans should be alike. But the arch-demons preserved earlier human types while other humans evolved onward. Thus, we wound up with lower races — who represent earlier stages of human development — and higher races — the ones that kept evolving. This became evident during humanity's time on Atlantis. Some humans evolved from period to period on Atlantis, as the gods intended. But the arch-demons kept some people behind in the older, less-evolved forms. "Lucifer and Ahriman...fought against [the] harmonious tendency of development in the evolution of humanity, and they managed to change the whole process so that various developments were shifted and displaced. While there should have been basically only one form of human being...Lucifer and Ahriman preserved the form of the fifth Atlantean period into the sixth, and again that of the sixth Atlantean period into the seventh, and even into the time after the Atlantean flood [i.e., the disaster that destroyed Atlantis]." )
"[T]his cosmic history is the backbone of Steiner’s work.”
— Gary Lachman, RUDOLF STEINER
(Jeremy P. Tarcher/Penguin, 2007), p. 147.
But let's return to our subject here, the planets.
Steiner defined our “universe” in various ways. The gods who are closest to mankind (Angels, Archangels) have evolved largely through the same planetary conditions as ourselves. But higher gods began their evolutions elsewhere, before our solar system first appeared. [See "Steiner Static".] Thus, Steiner's conception of the universe extends beyond our local corner and its little history. Steiner also made many references to the zodiac and its powers — astrology is important in the Steiner cosmology. [See "Astrology" and "Star Power".] The constellations of the zodiac are generally understood to exist well beyond the limits of our solar system, and Steiner usually seemed to share this understanding. His views were hardly modern or scientifically sophisticated, however. Thus, for instance, he referred to the “celestial dome,” which the ancients thought was a solid vault to which the stars are attached. Steiner seemed to believe in this mystical celestial roof. “Saturn's movement...is 1200 times [faster than] that of the whole celestial dome," Steiner said, for instance. 
Despite his references to celestial objects and conditions far, far away, Steiner sometimes indicated that our universe is limited to the solar system, that is, our immediate cosmic neighborhood. “To the modern materialistic view of the cosmos, Saturn is observed merely as a body moving about in cosmic space; and the same with the other planets. This is not the case; for if we take [i.e., consider] Saturn, the outermost planet of our Universe [sic], we must represent him as the leader of our planetary system in cosmic space. He directs our system in space.”  So the "universe" is the solar system, which is ruled or led by Saturn, the "outermost planet." (This statement is packed with errors. In reality, the outermost planet — if we disregard Pluto and the other minor planets beyond it — is Neptune. And the controlling power in the solar system is the Sun — that's why the system is called the "solar" system. Etc. But moving on...)
Steiner said that the various planets in our universe (or truncated solar system) do not all exist in the same three-dimensional space: “If we employ the three-dimensional space to sketch in the orbits of Jupiter, Saturn and Mars, we come at most to a boundary, where we get something like a path of the Sun. But if we wish to draw the others [i.e., the paths of the other "planets"], we can no longer do so in the three-dimensional space, we can only get shadow-pictures of these other movements in it; we cannot draw the path of Venus and that of Saturn in the same space ... That is to say, we cannot delineate the ordinary solar system in the three-dimensional space.”  (This statement, too, is wrong. All planets can be delineated in the same sort of space, since they all occupy regions in the same sort of space — specifically, the space or space-time continuum that is quaintly known as reality. But moving on..).
According to Steiner, different planets move due to the effect of different forces, and they move in strange ways, describing “lemniscates” (figure eights): “[W]e must realise that each cosmic body which follows such a path (lemniscate) is obviously moved in this path by forces, but each one by forces of a different kind.”  (Once again, Steiner is simply wrong. All of the members of the solar system move in response to the same force: gravity. And they all move in elliptical orbits; none moves in a lemniscate.)
Steiner often (but, contradicting himself, not always) denied that the planets orbit the Sun. “[W]e can certainly speak of a daily motion of the Earth around her axis, but by no means of a yearly motion of the Earth around the Sun. For the Earth follows the Sun, describing the same path. [paragraph break] Were the Earth revolving round the Sun, we should expect her axis, which owing to its inertia remains parallel, to point in the direction of different fixed stars during this revolution. But it does not! If the Earth revolved round the Sun, the axis could not indicate the direction of the Pole-star, for the point indicated would itself have to revolve round the Pole-star....”  [To observe Steiner waffling on the question of whether the planets orbit the Sun, see "Deception".]
The catalogue of Steiner's astronomical errors is exceedingly large. But let's press ahead to hear Steiner out on the nature of the various "planets" in our "universe."
The physical Moon conceals the true, inner, spiritual Moon — where some very publicity-shy spirits live. “When we speak of the Moon as a physical body in the heavens, its physical nature is only the external, the most external, revelation of the Spiritual behind it. To those who have knowledge of both its outer and its inner nature, the Moon in our universe presents itself to begin with as a gathering of spiritual Beings living in great seclusion.” 
The Moon reflects everything that impinges upon it while guarding its own secrets. The occupants of the Moon were once the spiritual guides of humanity, but they left the Earth when the Moon itself separated from the Earth. Now they hold their tongues. “The spiritual Beings peopling this innermost sphere of the Moon are Beings who shut themselves off in strict seclusion from the rest of the universe. They live in their Moon 'fortress' ... If we succeed in fathoming this mystery — I will call it the Moon-mystery of the universe — we realise that these Beings who have now entrenched themselves in the Moon fortress were once the great Teachers of earthly humanity; but all consciousness of the realities, of spirit and soul hidden in this fortress has been lost. What is still transmitted to the Earth from the heavens represents only what the outer surface, the walls, as it were, of the Moon fortress radiate back from the rest of the universe ... [T]he highest wisdom once possessed by the Earth lies concealed within the Moon fortress.” 
Our loss, obviously. Steiner’s stated goal was to reacquire the lost wisdom as well as all other “mystery” wisdom. Such wisdom is what “Anthroposophy” (“human wisdom”) is supposed to convey.
By the way, note the phrase "earthly humanity." Some "humans" are not of this Earth. Indeed, Steiner taught that "human" is a stage of development. Various gods were once human in their own way before evolving to higher status. [See "human stage of evolution" in the Brief Waldorf / Steiner Encyclopedia.]
Saturn is very hung up on “himself” (Steiner referred to Saturn and other planets by their genders — the difference between a planet and its presiding god tends to blur). As we have seen, Saturn is the "leader of the solar system." He is also the historian of our universe. “We turn now to Saturn ... [Saturn is] a kind of antithesis to the Moon. [paragraph break] The nature of Saturn is such that he receives many diverse impulses from the universe but allows none of them to stream back — at all events not to the Earth ... Saturn is an entirely self-engrossed heavenly body in our planetary system, raying [i.e., sending] his own being into the universe ... He speaks only of himself, tells us only what he himself is. And what he is reveals itself gradually as a kind of memory of the planetary system.” 
Like the other planets, Saturn has occupants. They and their host can seduce us if we are not careful. “[T]he hosts of Beings indwelling Saturn lend their attention to the outer universe, but...they speak only of past cosmic events. That is why Saturn is like a kaleidoscopic memory of our planetary system. As a faithful informant concerning what has come to pass in the planetary system, he [i.e., Saturn] holds its secrets of this kind within himself ... Saturn is the constant tempter of those who listen to his secrets; he tempts them to give little heed to earthly affairs of today and to immerse themselves in what the Earth once was ... Those who have a particular inclination towards Saturn in earthly existence are people who like to be gazing always into the past, who are opposed to progress, who ever and again want to bring back the past." 
Jupiter and his occupants are oriented to the present. As a “thinker,” Jupiter can help guide our own thinking, although the “thinking” that Jupiter enables is not what many of us would call thinking — it is more like intuition, or fantasy, or dreaming. Steiner often said that we can receive wisdom while asleep; as it turns out, some of this wisdom comes from Jupiter. “Jupiter is the Thinker in our planetary system, and thinking is the activity cultivated by all the Beings in his cosmic domain. Creative thoughts received from the universe radiate to us from Jupiter. Jupiter contains, in the form of thoughts, all the formative forces for the different orders of cosmic Beings. Whereas Saturn tells of the past, Jupiter gives a living portrayal of what is connected with him in the cosmic present ... A man who has tried hard to apply clear thinking to some problem but cannot get to the root of it, will find, if he is patient and works inwardly at it, that the Jupiter powers will actually help him during the night. And many a one who has found a better solution for some problem during the night, as though out of dream...would have to admit, if he knew the truth, that it is the Jupiter powers who imbue human thinking with mobility and vigour ... Modern man has to depend more upon receiving the memory of Saturn and the wisdom of Jupiter separately in the course of his spiritual development.”  (We've probably all had the experience of waking up with a new idea in mind, a solution to a problem that bugged us yesterday. The brain does keep working at night, but attributing this to Jupiter is (to put this mildly) a stretch.)
As we all know by now, after our evolution during "Present Earth" is finished, we will proceed to life on "Jupiter" — not the planet, as such, but the next stage of cosmic development, specifically Future Jupiter. [See "Future Stages".]
Mars is an interesting planet. It is not the manifestation of a planetary condition of the same name — there was no Old Mars and there will be no Future Mars. Mars is actually a reincarnation of Old Moon [see "Everything"], and it holds other surprises as well. “Mars may be called the great 'Talker' in the planetary system ... Mars is constantly blurting out to the souls in his sphere whatever in the cosmos is accessible to him — which is not everything. Mars...is particularly active when human beings talk in sleep or in dream ... Mars does little thinking. He has few thinkers, but many talkers, in his sphere. The Mars Spirits are always on the watch for what arises here or there in the universe and then they talk about it with great zest and fervour ... In a certain sense Mars may be called the Agitator in our universe. He is always out to persuade, whereas Jupiter wants only to convince.” 
Note the references to the "sphere" of Mars. In occult science, the solar system is sometimes conceived as a series of concentric spheres. Each sphere has the radius of a planet's orbit (if we concede that planets do move in orbits). Thus, the sphere of Mars is the part of the solar system bounded by the orbit of Mars. The sphere of Earth is inside the sphere of Mars, and the sphere of Venus is inside the sphere or Earth, and so on. The presiding gods of the planets have great influence over everything that happens inside their spheres. [See "Higher Worlds".]
Mars the planet is made of jelly, more or less. It is more alive than the Earth, having a more watery atmosphere. (All of this will come as a great surprise to NASA investigators whose Mars landers have found a generally dead, dry planet.) “Mars consists primarily of a more or less fluid mass, not as fluid as our water but, shall we say, more like the consistency of jelly, or something of that kind. There are also dense components, but they are not as densely solid as those of our earth. Their consistency would be more comparable to that of the antlers or horns of our animals, which form out of the general mass and dissolve back into it again ... [E]verything on Mars is much more full of life than on the earth. The earth is a dead planet in a far stronger sense than Mars, on which everything is still more or less living ... The air currents on Mars are much more full of life, much more watery.” 
Surprisingly, considering that Mars is the planet of war, many Mars beings are quite sweet. Also they circulate through us, as do other “astral” beings: Many Martians are “beneficent beings who, compared even with the mildest human nature, are yet much, much milder — in their speech too, [they are] very mild and gentle ... [T]hey inhabit Mars and are in fact the main population — as certain human races are the principal population on our earth ... [Wherever on Earth] love and kindliness prevail, where humanitarianism is unfolded, there you find the mild, gentle Mars beings present as astral creations, taking part in the forces which are there at work. That is nourishment for them, the atmosphere in which they can live and whence they exercise their influence on man ... [T]he preponderance of moon beings or Mars beings...circling through a man gives his lymph its special character. If more moon beings circulate through his body he is a man who inclines more easily to wrong-doing, irritation, and anger, if more Mars beings, then he is a man who is more inclined to gentleness, kindliness, mildness.”  NASA, and American Medical Association, and American Psychiatric Association: Take note.
Venus, being a virgin, keeps to herself (yes, Steiner uses the female pronoun). She loves Earth, however, and she listens to Mars. When Mars and Venus are in conjunction, the effects on Earth are unfortunate. “Venus wards off the universe. She is difficult to approach; she does not want to know anything about the universe. Her attitude is that if she were to expose herself to the external universe, she would lose her virginal nature. She is deeply shocked when any impression from the external universe attempts to approach her ... On the other hand, Venus is highly responsive to everything that comes from the Earth. The Earth is, so to speak, her lover ... The secrets of men in their earthly existence are transformed by Venus into dream-pictures of infinite diversity. She has a very great deal to do with poets, although they are not aware of it ... As I said before, she declines every would-be suitor, but for all that she listens attentively to the utterances of Mars. She transforms and illumines her dreamlike experiences of earthly things with what is communicated to her from the universe through Mars ... If we want to understand the impulses in the universe connected with the formation of human speech, we must turn our gaze to this strange life that weaves between Venus and Mars ... [A] language tends to become superficial, poor in qualities of soul, when Venus and Mars are in conjunction, and this in turn has an influence upon the people or nation concerned.” 
There are both good and bad beings on Venus, as on all celestial spheres. Each planet has a genius and a demon, and the various other beings on each planet follow one or the other of these leaders. “[W]e find certain beings who in their own way are also of a mild, peaceable nature and who in a certain respect are extraordinarily clever. These beings...have their actual home on the planet Venus, as the other beings [find homes] on moon and Mars. On Venus too we find yet a second species of beings who — in contrast to the gentle, amiable kind — present a wild and furious vitality, and whose principal occupation consists in mutual fighting and plunder ... Influences of the Venus beings live in all the plants and naturally also in the animal kingdom [on Earth]. The influences may come on the one hand from the good, gentle, mild Venus beings, or on the other hand, from the wild beings who have been described to you as greedy for plunder and engaged in conflict with each other. According as the one or the other kind work upon our animals and plants, so are virtues or vices built into man's body when the flesh of these animals or the food obtained from these plants are transformed into the chyle [a milky fluid in the body involved in digestion].” 
After our Jupiter planetary condition, we will evolve to our Venus planetary condition — Future Venus. [See "Future Stages".]
Mercury is a bit prosaic, but seen in the context of other celestial orbs, it is highly significant. Certain "Masters" — occult insiders, beings clued into deep mysteries — live on/in the various planets, including Mercury. “We come next to Mercury. In contrast to the other planets, Mercury is not interested in things of a physical, material nature as such, but in whatever is capable of co-ordination. Mercury is the domain of the Masters of co-ordinative thinking; Jupiter, the habitation of the Masters of wisdom-filled thinking ... Mercury provides the forces for capacities of intellect and reason, especially of intellect. The Masters of the forces of co-ordinative knowledge and mental activity have their habitation in Mercury. [paragraph break] There is a remarkable connection between these planets and the life and being of man. The Moon...builds and fashions the outer form, the body of man. It is therefore by the Moon that the forces of heredity are incorporated in his bodily constitution ... [S]cience speaks under the influence of the demonic Mars-forces and has not even begun to approach the real mysteries of heredity ... Venus and Mercury bring into the human being the karmic element that is connected more with the life of soul and spirit and comes to expression in his qualities of heart and in his temperament. On the other hand, Mars, and especially Jupiter and Saturn when a man has a right relationship with them, act as liberating factors. They wrest man away from what is determined by destiny and make him into a free being ... Mars, Jupiter and Saturn may also be called the liberating planets; they give man freedom. On the other hand [sic], Venus, Mercury and the Moon may be called the destiny-determining planets.” 
Circling back to the Moon for a moment: "The Moon...builds and fashions the outer form, the body of man." Actually, Jehovah did this. Jehovah is not God — he is a Moon Being (Jews mistakenly worship him; theirs is a Moon religion, Steiner explained). Jehovah, using his Moon forces, created the physical form of mankind. [Take a peek at "Clairvoyant Vision", "Steiner's Bile", and "The White Lodge".] All of the "planets" and "stars" — and their presiding gods — have exerted their influences downward to us. Here we have seen a bit of Mercury's work.
Vulcan does not exist. But occult science generally says that it does. To believers, Vulcan is the most mysterious member of our solar system. It may be Mercury, or it may be another planet, hidden by Mercury, or something else. It is so near the Sun that we can’t see it (it may hide behind the Sun). Yet it is real, and our seventh planetary condition will bear its name. In the past, when humans dispersed to the various planets, some went to Vulcan (proving that the planet really exists, perhaps). And today, Vulcan beings (the nonhuman occupants of Vulcan) are already here, among us. According to Steiner:
“You will remember the passage in the book OCCULT SCIENCE dealing with the time when the human souls ascended to the planets and afterwards descended once more to earth-existence. I spoke of how the Mars-men, the Jupiter-men and the others descended again to earth. Now an event of great significance came to pass at the end of the seventies of last century [i.e., the 1870s]. It is an event that can be described only in the light of facts which are revealed to us in the spiritual world. Whereas in the days of old Atlantis human beings came down to the earth from Saturn, Jupiter, Mars, and so on — that is to say, beings of soul were drawn into the realm of earth-existence — since the end of the seventies of last century, other Beings — not of the human order — have been descending to the earth for the purposes of their further development. From cosmic realms beyond the earth they come down to the earth and enter into a definite relationship with human beings. Since the eighties of the nineteenth century [i.e., the 1880s], super-earthly Beings have been seeking to enter the sphere of earth-existence. Just as the Vulcan-men [sic] were the last to come down to the earth so now Vulcan Beings are actually coming into the realm of earthly existence ... [This is a serious matter:] Super-earthly Beings are already here, and the fact that we are able to have a connected body of Spiritual Science at all today is due to the circumstance that Beings from beyond the earth are bringing the messages from the spiritual world down into earth-existence ... Today people may consider it comparatively harmless to elaborate only those automatic, lifeless thoughts which arise in connection with the mineral world and the mineral nature of plant, animal and man. Materialists revel in such thoughts which are — well — thoughts and nothing more. But try to imagine what will happen if men go on unfolding no other kinds of thoughts until the time is reached in the eighth millennium for the moon-existence to unite again with the earth. These Beings of whom I have spoken will gradually come down to the earth. Vulcan Beings, ‘Supermen’ of Vulcan, ‘Supermen’ of Venus, of Mercury, of the Sun, will unite with this earth-existence. But if human beings persist in nothing but opposition to them, earth-existence will pass over into chaos in the course of the next few thousand years."  I'll bet you didn't know these facts, did you?
[For more on Vulcan, see "Vulcan".]
"[Steiner’s] vision of the world, the universe,
and cosmic history...
is more like science fiction than anything else.”
— Anthony Storr, FEET OF CLAY
(Free Press, 1996), p. 81.
Steiner also spoke of Uranus and Neptune, sometimes, but he basically excluded them from the solar system. ("Uranus and Neptune...circle much farther out and their orbits exhibit such irregularities that in reality they cannot be counted among the planets even today.” ) So this concludes our planetary tour.
Bear in mind that our little survey is incomplete. Not only have we omitted Uranus and Neptune, but we have failed to perceive what we are unable to perceive, the invisible planets: "There are many planets that are not to be seen with physical eyes, such as those in the first, second, and third elementary kingdoms. Only when such a planet within creation enters the mineral kingdom can it be seen." 
So that's the end of the tour.
Be sure to take your things with you as you file out of the planetarium.
— Roger Rawlings
How much of all this will Waldorf teachers pass along to their students? It depends. Some Waldorf teachers and schools will keep Steiner's occultism well concealed in the background, whereas others will bring it forward to varying degrees. Waldorf students may be told some remarkable things about the zodiac, the stars, and the planets — they may be taught some Anthroposophical doctrines about these subjects. It is less likely that the students will be told about "planetary conditions" of cosmic evolution. But, then again, in some rare instances even this deeply esoteric lore may find its way into Waldorf classrooms. In the Waldorf teachers' guide ANCIENT SATURN TO ATLANTIS (Golden Beetle Books, 1991), Waldorf teacher-trainer Alan Whitehead advocates laying out the occult history of the cosmos in detail for Waldorf students. [See "Out in the Open".]
To learn more about
some of the topics
we have broached,
you may also want to consider
“[T]he great majority of human souls had to relinquish their union with the earth. Here we come to something of great importance in the relationship between man and earth, something which happened during the time between the separation of the sun and that of the moon. During this interval human soul-spirits, except for a very small number, abandoned earthly conditions, and pressing upward into higher regions, continued their evolution upon the several planets belonging to our solar system, each according to the stage of his development. Some souls were fitted to pursue their evolution on Saturn, others on Mars, others again on Mercury, and so on. Only a very small number of the strongest soul-spirits remained in union with the earth. During this time the rest dwelt upon the earth's planetary neighbours. This came about at a time preceding (to use our own terminology) the Lemurian age.” — Rudolf Steiner, GENESIS: Secrets of the Bible Story of Creation (Anthroposophical Publishing Co., 1959), lecture 9, GA 122.
Mystic planetary emblems that
may be found in Waldorf schools:
Sun, Saturn, Venus.
[R.R. sketches, 2010, based on pp. 197-199,
John Fletcher's ART INSPIRED BY RUDOLF STEINER
(Mercury Arts Publications, 1987).]
There are similar Steiner-indicated emblems
for the other "sacred planets."
An Anthroposophical summary:
"Keeping Track of the Planets".
The geniuses of the planets.
AN ENCYCLOPEDIA OF OCCULTISM
(Dover, 2003), facing p. 241.]
The occultism found behind and in Waldorf schools differs from other forms of occultism is many ways — it derives directly from Rudolf Steiner’s specific doctrines. But there are also many links between Anthroposophy and occultism at large. In essence, Steiner studied many types of occult teachings and attempted to reconcile them in one body of über-teachings: his own body of work, Anthroposophy.
[AN ENCYCLOPEDIA OF OCCULTISM, p. 47.]
Steiner designed mystic columns for use in Anthroposophical buildings. There are seven column designs, representing the seven classical planets of astrology. Here you see the design for the Mars column:
"In the year 1907 Rudolf Steiner published the collection OCCULT SEALS AND COLUMNS ... The pictures, based on his sketches and instructions, have been drawn and re-drawn by a number of artists ... [T]he seven Seals and Columns decorated the Lecture Hall at the Congress of European Sections of the Theosophical Society, held in 1907 in Munich, where Rudolf Steiner and his pupils were responsible for the arrangements ... The designs of the seven Columns were afterwards reproduced in fully plastic form in the great wooden pillars supporting the large dome of the first Goetheanum [the Anthroposophical headquarters]." — George Adams, note in Rudolf Steiner's VERSES AND MEDITATIONS (Rudolf Steiner Press, 2004), pp. 227-228.
(When Steiner first turned to occultism, he joined the ranks of Theosophists. Later, having absorbed and reworked basic Theosophical doctrines, he broke away to establish his own spiritual movement, Anthroposophy. [For a quick survey Theosophy, see "Basics".])
The images above depict conditions for human beings when, according to Steiner, the Earth was inside the Sun (left), and now when the Sun and Earth are separate (right). “[T]he sun's influence keeps human beings small ... Now that the sun is separate, the earth receives far less radiation from it. When the sun was still united with the earth, all its forces reached the earth from within. No wonder that now, as the sun rotates, it can shine upon a human being at every point on the earth, but in ancient times, when it had to send out its rays from the centre of the earth, it was able to project its forces upon only one human being. Once the sun began to work out at the periphery, it made human beings smaller.” — Rudolf Steiner, FROM CRYSTALS TO CROCODILES (Rudolf Steiner Press, 2002), pp. 162-163. [R.R. sketch, 2009, based on the image on p. 162. My color choices indicate that the Sun was inside the Earth; but Steiner also said the opposite: “If this is the earth, which I am drawing very small, and if that is the sun, with the earth in it...” (p. 163). His point was that all of the solar system was at one time a single globe.]
Various parts of Steiner's statements on such matters make no sense — such as saying that the Sun shines on all people because it rotates, or that the Sun causes people to be small. Still, on some occasions, Steiner made sense about the movement of the Earth today. He said the Earth orbits the Sun. “Here is the sun and there is the earth, which rotates around the former..." (p. 163). Good. But Steiner didn't leave well enough alone. On other occasions, as we have seen, he said that the Earth does not orbit the Sun. Below is a copy of another sketch Steiner made, in this case illustrating for Waldorf teachers the "actual" movement of the planets and Sun. The planets travel in line with the Sun, along a twisting path. Saturn (blue) leads, the Sun (yellow) is in the middle, and the Earth (green) brings up the rear. Neptune and Uranus are not really members of the solar system and thus are not included. Seen from before or behind, the twisting line describes a lemniscate (mottled blue). In other words, we travel along a twisting, spirally path that rises and falls as it shifts left and right; the path has a stretched-out, lemniscatory shape.
"[I]t is not that the planets move around the Sun, but these three, Mercury, Venus, and the Earth, follow the Sun, and these three, Mars, Jupiter, and Saturn, precede it.” — Rudolf Steiner, FACULTY MEETINGS WITH RUDOLF STEINER (Anthroposophic Press, 1998), pp. 30-31. [R.R. sketch, 2008, based on the illustration in the book.]
Here are the planets lined up with the Sun, traveling together as Steiner described (but bunched up for clarity's sake). [R.R. sketch, 2010.]
"Whither does all this lead? ... [W]e can no longer, with the Earth here (diagram) attribute to any one point a circular motion. On the contrary, we must form the conception that the Earth in actual fact proceeds along her path in such a way as to produce a line like that of the lemniscate. The motion is not a simple revolution, but a more complicated movement; each point of the terrestrial surface describes a lemniscate...." — Rudolf Steiner, MAN: HIEROGLYPH OF THE UNIVERSE (Rudolf Steiner Press, 1972), lecture 6, GA 201.
"[T]he Earth moves behind the Sun in a screw-like line, the Earth moving along always with the Sun. And then if we view the line from above, we get a projection of the line and the projection shows a lemniscate." — Ibid. [R.R. sketch, 2010.]
"Coming now to describe rather more in detail how we take our way after falling asleep, we find we can distinguish different spheres through which we pass. First comes the sphere where the I and the astral body — that is to say, the soul of man as it finds itself in sleep — feel united with the movements of the World of the planets. When we wake up in the morning and slip into our physical body, we have in us, as we know, our lungs, our heart, our liver, our brain. In the first sphere with which we come in contact after falling asleep — and it will also be again the last sphere we enter before awaking — we have in us the forces of the movements of the planets. This does not mean of course that we receive into us every night the entire planetary movements; we carry within us a little picture, as it were, wherein the movements of the planets are reproduced. And this picture is different for each single human being. That, then, is the first experience every one of us encounters after falling asleep. We follow, as it were, with our astral body all that happens with the planets, as they move out there in the wide spaces of the Universe; we experience it all in our astral body in a sort of planetary globe." — Rudolf Steiner, PLANETARY SPHERES AND THEIR INFLUENCE ON MANS LIFE ON EARTH AND IN THE SPIRITUAL WORLDS (Rudolf Steiner Press, 1982), lecture 3, GA 214. [R.R. sketch, 2010. Departing from Steiner's standard of strict, literal truth, I have allowed myself a certain interpretive freedom here.]
“Before the Lemurian age the sun, moon, and earth, united in one body, moved forward in terms of the zodiac. Time was measured following this movement. For this reason, the twelve signs of the zodiac are characterized as the heavenly clock and drawn as such.
“A planet alternates between pralaya, a cosmic night, and manvantara, a cosmic day, just as we alternately pass through day and night. The planet passes through the signs of the zodiac during both pralaya and manvantara; for that reason the twelve signs of the zodiac are counted twice, just as we also count two times twelve to equal twenty-four hours. The hours symbolize the signs of the zodiac. The united sun, moon, and earth also moved through the cosmic days and nights according to the heavenly clock. Then their separation occurred.” — Rudolf Steiner, READING THE PICTURES OF THE APOCALYPSE (SteinerBooks, 1993), pp. 21-22. [R.R. sketch, 2010, based on the one in the book. I have filled in astrological signs, numbers, and clock hands — Steiner's sketch is awfully empty.]
The image in the book.
The number and identity of the "planets"
differ in various representations.
In this non-Anthroposophical image,
we find nine. Starting at the upper right
and proceeding clockwise, they are Sun, Moon,
Neptune, Uranus, Saturn, Jupiter,
Mars, Venus, and Mercury.
[Alighieri, Dante LA VITA NUOVA (1910).]
Painting by a Waldorf student,
Whatever is right or wrong about Waldorf schools, the source lies in Steiner's occultism. He acknowledged that we live in the physical universe, and he admitted (sometimes) that science describes this universe with some precision. But he also claimed that we simultaneously live in other universes, which are truer. Here is a version of the etheric universe. Steiner attributed this description to the ancients, but it is close to his own view. In the center you see the Earth (green). Surrounding it is Hell or the Abyss (red), the barrier that divides us from the rest of the etheric universe. [See "Hell" and "Sphere 8"]. Outside Hell is the sphere of the Moon (gray). This sphere encloses the Earth: We live in the Earth sphere but also inside the Moon sphere, making us subject to Moon forces. Outside the Moon sphere are other, increasingly larger spheres, each of which encloses all of the smaller spheres. We live within all of these larger spheres and are subject to their forces. In order, the spheres are Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and the crystal heaven or the realm of fixed stars. Essentially, this is the ancient astrological description of the heavens.
“[T]he idea was that the earth was inside the moon, and the bit we see of the moon is only a tiny, solid part of it ... [I]f the earth were not within the powers of the moon, human beings...would not be able to procreate ... If human beings did not have the powers of Mercury in them all the time they would not be able to digest ... Venus lives in our blood. Everything that has to do with blood in us comes from the powers of Venus ... [T]he powers of the sun are above all active in the human heart ... Mars...is connected with everything to do with speech and everything we have by way of breathing organs ... Jupiter...has to do with our brain, really our sense organs, our brain with the sense organs ... Saturn has to do with our organs of thinking ... Copernicus' image of the world [i.e., the physical, scientific image] has all been calculated. Those earlier people [the ancients, who were wiser] did not make calculations. But they knew something else, something modern people do not know. They knew that the powers were active everywhere in the world, wherever you look. But these powers, which are also in the human being, are not in the world we see with our eyes; they are in the invisible realm ... Dante [who presented the ancient view] was therefore speaking of a very different world, an etheric world ... [H]e wrote of the invisible realm, of the etheric world." — Rudolf Steiner, FROM LIMESTONE TO LUCIFER (Rudolf Steiner Press, 1999), pp. 41-45. [R.R. sketch, 2009, based on illustration on p. 42.]
Note the distinction between the brain and our "thinking organs." This is just one of the many peculiarities in the visions Steiner endorsed. Essentially, he accepted the ignorance of the ancient peoples, calling it wisdom; and he rejected the knowledge of modern science, calling it ignorance. People of faith today may agree that a spiritual realm exists, but in considering Waldorf schools, they should ask themselves whether the true spiritual realm is the place Steiner described, a realm of celestial spheres, astrology, clairvoyance, and all the other esoteric elements of Steiner's doctrines.
"[R]ed human blood is connected with the evolution of the Earth as such. It could not have been formed at all if the Earth, in its evolutionary course, had not come together with another planet, namely, with Mars. Before this contact of the Earth with Mars, the Earth had no iron; there was no iron in the blood; the blood upon which the human being is dependent today, did not exist. In the first half of Earth existence, the influence of the planet Mars is the ruling factor, and the influence of the planet Mercury in the second half.
"Mars has given iron to the Earth and the Mercury influence manifests on the Earth in such a way that it makes the human soul more and more free, more and more independent. In occultism therefore, we speak of the Mars half of Earth evolution and of the Mercury half. Whereas the other names describe a whole planet, Earth evolution is spoken of as 'Mars-Mercury.' Used in this connection the names do not designate the planets we know today but the influences at work during the first and second halves of Earth evolution.
"In the future the Earth will incarnate as a new planetary body, known as Jupiter. The human astral body then will have developed to a stage where it no longer confronts the physical body as an enemy, as is the case today, but it will still not have reached its highest stage. The etheric body on Jupiter will have reached the stage at which the physical body is now, for it will then have three planetary evolutions behind it as the physical body has today.
"On the planetary body following Jupiter, the astral body will have developed as far as the physical body of today; it will have behind it the Moon, Earth and Jupiter evolutions and will have reached the Venus evolution. The final planetary incarnation will be that of Vulcan, when the 'I', the Ego, will have attained the highest stage of its development. The future incarnations of the Earth will thus be: Jupiter, Venus and Vulcan."
— Rudolf Steiner, THEOSOPHY OF THE ROSICRUCIAN (Rudolf Steiner Press, 1966), pp. 79-80.
Steiner knew that his terminology could be confusing. Here is his effort, in a Supplementary Note at the end of OCCULT SCIENCE, to explain the differences — and connections — between planetary conditions, such as Old Saturn, and planets, such as Saturn:
"In the fourth and sixth chapters of this book it was described how the World to which Man belongs, and Man himself, evolve through the successive states called ‘Saturn, Sun, Moon, Earth, Jupiter, Venus and Vulcan.’ Some indication was also given of how human evolution is related to the existing heavenly bodies other than the Earth — Saturn, Jupiter and Mars, for example. They too are of course evolving, and in their present stage of evolution the physical part of them is perceptible to our senses in the forms known to physical Astronomy as ‘Saturn’, ‘Jupiter’, ‘Mars’ and the rest.
"Seen in the light of spiritual science, the present Saturn is a kind of reincarnation of Old Saturn. It came into existence because, before the Sun had separated from the Earth, Beings were there who would not have been able to leave with the Sun. They were so much imbued with Saturnian characteristics that they could not live where Solar properties above all were to be developed. So too the present Jupiter arose because Beings were there with characteristics which cosmic evolution as a whole will be unfolding in the future Jupiter and not till then. Mars on the other hand is a heavenly body inhabited by Beings whose evolution on Old Moon was such that they could not have benefited from any further progress upon Earth. Mars is a reincarnation of Old Moon on a higher level. The present Mercury is a dwelling-place for Beings who are ahead of earthly evolution in that they have developed certain earthly qualities in a higher form than is possible upon the Earth herself. Likewise the present Venus is a prophetic anticipation of the future Venus state.
"Such are the reasons for naming the past and future stages of World-evolution after the heavenly bodies — their present representatives, as it were, in the Cosmos."
— Rudolf Steiner, OCCULT SCIENCE - AN OUTLINE (Rudolf Steiner Press, 1969), pp. 328-329.
Some illustrations on each page here at Waldorf Watch
are closely connected to the essay on that page;
others are not — they provide general context.
 See my essay “Everything” and the essays that follow it.
Depending on context, Steiner used the name of a planet for the planet, or for a stage of evolution, or for the "sphere" or "globe" of the planet — a spiritual region corresponding to the space enclosed by the apparent orbit of the planet.
I will explain at least some of this, here, while allowing the mind-spinning complexity (and, perhaps, internal confusions) of Steiner's teachings to reveal themselves.
 Rudolf Steiner, WONDERS OF THE WORLD (Rudolf Steiner Press, 1983), p. 77.
 Rudolf Steiner, AT THE GATES OF SPIRITUAL SCIENCE (Rudolf Steiner Press, 1986), lecture 9, GA 95.
 Rudolf Steiner, OCCULT HISTORY (Rudolf Steiner Press, 1982), p. 36.
We can, perhaps, get Steiner off the hook if we stipulate that the souls who moved to other planets were not quite human, yet. "Human" is a plastic term, in Anthroposophy. It may apply to us and our forebears (who were us, in earlier incarnations), or only us as we are now (humans as humanity is today), or to all beings who have evolved through a stage equivalent to our current stage of development. The gods who are one level higher than humanity today, for instance, once stood at a developmental level equivalent to our level today. "Man has only become human, in the present sense of the word, on earth. The former planetary conditions, which the earth has passed through had a similar task. Other beings became human on those other planets [i.e., during those phases of evolution], and now stand at a higher stage than man ... The Archangels [for instance] were first able to become human on the Sun [i.e., during Old Sun]....” — R. Steiner, THE SPIRITUAL HIERARCHIES (Anthroposophical Publishing Co.), lecture 3, GA 110.
Concerning "ever new incarnations": As you may have gathered, reincarnation is a basic Anthroposophical belief. See "Reincarnation".
 Rudolf Steiner, AN OUTLINE OF ESOTERIC SCIENCE (Anthroposophic Press, 1997), pp. 238-239.
 Rudolf Steiner, THE UNIVERSAL HUMAN (Anthroposophic Press, 1990), p. 75.
 Rudolf Steiner, OCCULT SIGNS AND SYMBOLS (Anthroposophic Press, 1972), p. 11.
 Rudolf Steiner, MAN - HIEROGLYPH OF THE UNIVERSE (Rudolf Steiner Press, 1972), lecture 9, GA 201.
To be precise, the real universe consists of four dimensions: height, width, depth, and time. String theory postulates many additional dimensions, but these remain speculative. In any event, all planets occupy the same sort of space, the universal space, however many dimensions this ultimately comprises.
 Rudolf Steiner, “The Spiritual Individualities of the Planets” (THE GOLDEN BLADE, 1988), a lecture, GA 228.
 Rudolf Steiner, THE EVOLUTION OF THE EARTH AND MAN AND THE INFLUENCE OF THE STARS (Anthroposophic Press, 1987), lecture 10, GA 354.
 Rudolf Steiner, THE INFLUENCE OF SPIRITUAL BEINGS ON MAN (Anthroposophic Press, 1961), lecture 1, GA 102.
 “The Spiritual Individualities of the Planets”.
 “The Influence of Spiritual Beings on Man”.
 “The Spiritual Individualities of the Planets”.
 Rudolf Steiner, "Picture of Earth-Evolution in the Future" (THE GOLDEN BLADE, 1960), a lecture, GA 204.
 Rudolf Steiner, FROM COMETS TO COCAINE (Rudolf steiner Press, 2000) , p. 290.
 OCCULT SIGNS AND SYMBOLS, pp. 40-41.
Detail, Waldorf student art.