The Tree of Life is a diagram before it is a doctrine: 10 nodes, 22 lines, 3 columns. Astrolium uses it as a structural lens on a natal chart, and is careful about which tradition that borrows from.
The Tree of Life is a diagram of 10 sephiroth connected by 22 paths, arranged in 3 vertical columns known as the pillars of Mercy, Severity and the Middle. It originates in Jewish mystical literature, where the sephiroth are emanations rather than planets. The version used in astrology comes from Hermetic Qabalah, the Renaissance and Golden Dawn reworking that attaches a planet to each sephirah and a Hebrew letter, and often a tarot trump, to each path. That attribution layer is roughly 500 years old, not ancient, and several competing schemes exist. Astrolium weights the 10 sephiroth by the condition of the carrying planet in the natal chart and draws path strength from the aspect between the two ends.
The structure
Ten sephiroth run down the diagram from Kether at the crown to Malkuth at the base, with Tiphareth at the centre. Twenty-two paths connect them. Read as columns, the right-hand pillar of Mercy is expansive, the left-hand pillar of Severity is restrictive, and the Middle Pillar balances between them, which gives the figure its usefulness: it is a map of how force and form check each other.
In Jewish Kabbalah the sephiroth are divine emanations and the diagram belongs to a religious and textual tradition with its own rules of study. Nothing on this page is a claim about that tradition.
Where the planets come from
The planetary attribution is a Hermetic addition, most of it settled during the 400 years after the Renaissance. In the Golden Dawn scheme, Saturn carries Binah, Jupiter carries Chesed, Mars carries Geburah, the Sun carries Tiphareth, Venus carries Netzach, Mercury carries Hod and the Moon carries Yesod, with Malkuth as the sphere of the elements. The top of the diagram, Kether and Chokmah, is handled differently from lineage to lineage, and modern schemes push the outer planets into those positions where older ones did not.
The 22 paths carry the 22 Hebrew letters, and from the eighteenth century onward the 22 tarot trumps as well. Which letter belongs to which path is exactly where recensions disagree, so any serious presentation has to name the scheme it is using rather than present one as the truth.
Reading a chart on the Tree
The move an astrologer makes is straightforward: if Geburah is carried by Mars, then whatever Mars is doing in this chart tells you about the condition of Geburah here. A dignified, well-placed Mars gives a strong Severity node; a debilitated and besieged Mars gives a weak one. Do that for all 10 and the pillars come out unbalanced in a way that describes the nativity structurally rather than by house and sign.
Paths are read the same way through aspects. Where the two carrying planets are in harmonious aspect, the path between their sephiroth flows; where they are in hard aspect, it runs under tension; where there is no aspect, the connection is inert. This is a reading method, not a traditional doctrine, and it should be labelled as one.
Human Design borrows the same diagram from the other direction: its 9 centres are a rearrangement of the sephiroth crossed with the chakra system, which is why a bodygraph looks like a Tree that has been redrawn. The Human Design guide covers that lineage.
In Astrolium
The Kabbalah module draws the Tree for one nativity, weighting each sephirah by the condition of its carrier, essential dignity, accidental fortitude and sect, and weighting each of the 22 paths by the natal aspect between the two ends. 4 tree systems are selectable: Classical, Modern, Golden Dawn and an extended Golden Dawn. A provenance panel names the attribution behind the tree on screen and states outright that the reading layer is Astrolium's own and is neither ancient nor traditional Jewish Kabbalah.
Two flags keep the reading honest. A path ending on the Ascendant is marked time-sensitive, because that point moves with the clock, near 1 degree every four minutes at middle latitudes. A path with an outer planet at one end is marked generational, since everyone born within months shares it. The module needs a recorded birth time and refuses to substitute noon. For the chart layer underneath, see the natal chart entry and the essential dignities that decide how much weight a carrier gets.