Mars sign calculator

Mars is the planet of drive. In a birth chart it describes how you start things, how you compete, what makes you angry and what you do with the anger, and the kind of effort that comes naturally to you. Your Mars sign is the sign Mars was passing through when you were born. Where Venus describes what draws you, Mars describes how you move towards it.

It is worth knowing even if you never read another placement, because astrologers trace a good deal of everyday friction to it: why one person argues at once and another goes quiet for a week, why some people work in bursts and others at a steady grind, why one needs a rival and another only a deadline.

Unlike Mercury and Venus, Mars is not tied to the Sun, so your Mars sign can be any of the twelve whatever your Sun sign. It usually spends between five and nine weeks in a sign. Every twenty-five or twenty-six months it turns retrograde for two to nearly three months, and in those years it can stay in one sign for as long as seven and a half months, which is why people born many weeks apart can share a Mars sign.

Mars changes sign on about two days in a hundred. On those days, without a birth time, the calculator shows both signs and the local time of the change; with a time, it notes a change that fell within an hour of it.

About one birth in ten has Mars retrograde, and the result says whether yours does. Astrologers read it as drive that turns inward first: someone who plans, reconsiders and then acts, and whose anger is more often held than shown. Seen from Earth, Mars appears to move backwards when the Earth overtakes it on the inside track, around the time Mars is opposite the Sun and at its brightest in the night sky.

StarMap takes your birth date and time, turns them into Universal Time using the clock changes your birthplace has had over the years, and asks astronomy-engine where Mars appeared from Earth at that moment. The position is placed in the tropical zodiac and matches the Swiss Ephemeris to about an arcminute. The sign is the start: your whole chart shows the house Mars occupies, which needs a birth time, and the angles it makes to your Sun, Moon and other planets, which astrologers often weigh as heavily as the sign.