Last lesson you got the sentence. Planet is the what, sign is the how, house is the where, aspect is the conversation. Everything from here fills in those slots one at a time. You start with the what, the planet, the actor, the part of you that is doing something. And you start with the two that carry the most weight in the whole chart.
Before anything else, a small honesty that matters more than it looks. The Sun is a star. The Moon is a satellite going around the Earth. Neither one is a planet. Astrology has always known that and still groups them with the planets for reading purposes, under an older name: the two lights, or the luminaries. They are the brightest objects in the sky and they have been part of the system longer than any written record of it. I mention this because this kind of precision is how you tell careful astrology from careless astrology and you are learning the careful kind.
You already know your Sun sign and your Moon sign from the calculator in the second lesson. What you do not know yet is what the Sun and the Moon actually do in a chart, underneath the sign. The sign tells you how. This lesson is only about the what.
The Sun
The Sun is identity. Not the identity you perform for a room full of people but the one underneath that, the self that feels most like you when nothing is being performed. It shows up as vitality, as what fills you up and what quietly drains you when you spend too long away from it. It is also a direction. In many charts I have read over twenty years the Sun describes something a person spends the first half of life growing into rather than the thing they start with. Where it sits by sign and by house will color all of that and you will learn to read both layers later. For now hold the plain version. The Sun is who you are becoming.
The Moon
The Moon works differently from the Sun in almost every way and the chart reads differently when you understand that.
Where the Sun is the self you grow toward, the Moon is the self you already were before you had words for it. The one that reacts before you decide to react. It describes your emotional ground, what you need in order to feel safe, what you reach for when the day has been too much. It is the private self, the one your family saw and strangers almost never do.
I cannot count how many people I have sat with who knew their Sun sign for years and felt almost nothing when they heard it described, then heard their Moon and went quiet. Because the Moon sits closer to the truth of ordinary life. It is faster than anything else in the chart, completing the full circle in about a month while the Sun takes a year and that speed is part of why it maps the part of you that shifts. Your moods. The weather inside.
Why both
The Sun is where you are headed. The Moon is where you already live. A chart that leans hard into the Sun and ignores the Moon can look impressive from outside and feel empty from inside. The other way around, all Moon and no Sun, can feel safe but go nowhere for years. Most people lean one way. The chart tends to show which. That is something for a reading, not a lesson, but here you need to know that these two come as a pair and the pair comes first.
Find them
Open your wheel from the second lesson and look for them. You are not reading them yet. You are learning to see the planet as its own layer, the actor, before the sign tells you how that actor shows up. Say the plain sentence to yourself. This is my Sun, the self I am growing toward. This is my Moon, what I need and how I feel it. The signs will come later and change the color of both. By then you will already know what they are changing.
If you want to see them as real bodies out in space, the AstroVisor shows the sky in three dimensions for any date. Run time forward and watch the Moon move faster than everything else. It does the same thing above you right now.
You may notice a third great on that wheel. The calculator gave you a rising sign alongside these two and it matters just as much. But the rising sign is not a planet. It is the point where the where of the whole chart begins and you will understand it when you reach the block on houses. Let it sit there for now.