On 12 August the Sun and the Moon meet at the same degree of Leo, the twentieth. A new Moon is usually invisible: the Moon rises and sets with the Sun and keeps its lit face turned away. This one you can actually watch, because the conjunction falls close enough to the lunar nodes to become a total solar eclipse.

The second thing worth your attention is the sign. New Moons usually ask you to begin in private, to put a seed in the ground and leave it there. Leo asks for the opposite: it wants the thing to be seen, to carry your name, to be looked at by someone. In the days around 12 August you are working inside that contradiction.

What happens in the sky

Every month the Moon lines up with the Sun, but for that alignment to turn into an eclipse it has to land near the two points where the Moon's orbit crosses the Earth's. On 12 August it does: the Moon covers the whole disc of the Sun and blots it out for a little over two minutes at the best spot.

The band where the eclipse is total runs across the Arctic, Greenland, Iceland, the Atlantic, northern Spain and the far north-east of Portugal. It is the first total eclipse visible from mainland Europe since 1999. From the rest of Europe, from parts of North America and parts of Africa it shows up as a partial eclipse, with a bite taken out of one side of the Sun. If you plan to look at it, you need a certified solar filter: sunglasses will not do.

What makes it different from an ordinary new Moon

Eclipses attract a lot of fear, so let us clear that first: an eclipse does not announce a disaster and does not decide anything on your behalf. It works more like an accelerator and a spotlight. It switches on one area of your life and lights it up all at once, shows you what you had shelved, and speeds up a change that was already under way.

The practical difference from an ordinary new Moon is scale. A normal lunation plays out within the month; what an eclipse sets in motion can keep unfolding for weeks and even a few months, and the degree of sky it touched stays sensitive for longer. Often the meaning of what is happening only becomes clear well after the fact, not on the day itself.

The other difference is where things come from. Around a solar eclipse, situations tend to come at you from outside, without your having gone looking for them, and they carry an uncomfortable but useful question: what are you willing to let go of. It can be a clearing-out, where you end habits or commitments that mattered and now hold you in place. On the exact day your clarity is not at its sharpest, so it is better not to force a final decision right there.

A beginning that wants an audience

Leo is fixed Fire, and the Sun is at home here. This is not the flare of Aries that goes off and burns out. It is a steady flame that stays at the centre and warms whatever is near it. Leo matches the height of summer, the noon of the year, the moment the fruit is ripe. It is not the sign that starts things, it is the one that brings them to their peak.

When a solar eclipse falls here, in the sign where the Sun is at home, whatever gets moving expresses itself with force and a certain theatricality, and on a collective level it brings out Leo's themes of leadership and power. The degree it falls on sits in the last third of the sign, traditionally read as the most martial: the action starts fast.

Your beginning takes on that colour too. Whatever you set going in these days does not do well hidden away until it is perfect. You are better off picking one thing that genuinely concerns you, something you would enjoy building even with no immediate result, and telling somebody about it. Leo does not sow in the abstract: it sows what it cares about, and here the heart works as a way of choosing rather than as a mood. The useful question in these hours is not what suits you best, it is what you would want to carry your name.

Where to be careful

An eclipse amplifies something Leo already does: you act on instinct before you have worked out what you want, and in that moment the wish and the plan are hard to tell apart. Around the conjunction you may well mistake one for the other and announce something before you have built it.

Then there is the point where this sign turns out to be fragile. Saturn and Uranus are in detriment in Leo: rational coldness, caution and diplomatic calculation weigh on you here, which makes you generous but not great at measuring obstacles or timing. If you find yourself reacting badly to a comment on your work in these days, keep that in mind. It is not the comment, it is that you are starting the thing out in the open, and out in the open every look counts for more.

Leo's guiding myth is Heracles, who starts out in blind strength and needs twelve labours to come to terms with himself. The same arc runs here in miniature: the opening push is good, what makes it useful is keeping it in proportion. The guide to the signs has the full portrait of Leo, dignities and archetype at length.

Where you feel it most

It does not land the same way for everyone, and with an eclipse the gap is wider than usual. An eclipse really counts when it falls close to a point in your birth chart: the planet or angle it touches lights up and asks for attention for a while. The contacts you feel most are those to the Sun, the Moon, the Ascendant, the Midheaven and the planet that rules your chart. If you have important points in the late degrees of Leo, or of the other fixed signs (Taurus, Scorpio, Aquarius), you feel it directly.

For everyone else, look at which house of your chart this eclipse falls in: that is where something restarts and asks to be seen. It is not a forecast of a specific event, it is the terrain. That detail only shows up on your own chart, never on your Sun sign. If you have not calculated it yet you need your date, time and place of birth, and it takes a minute.

Two weeks later, on 28 August, a lunar eclipse follows in Pisces: the two are read together, as two beats of the same movement. In the meantime the Moon comes back as a thin crescent in the west, just after sunset. That is your sign that what you started has stopped being an intention.