lodestarAries is the name of both a zodiac sign and a constellation. It is easy to assume they are the same patch of sky. They are two different ways of dividing what we see, so the names can match while the boundaries do not.
Signs divide a circle into twelve equal parts
In the tropical zodiac used by much Western astrology, the Sun's apparent yearly path is divided into twelve signs of 30 degrees each. The first point of Aries is tied to the March equinox. A sign is a measured section of this system, even when it shares a name and picture with a group of stars.
Constellations map the visible sky
Astronomers use constellations as named regions of the sky. The International Astronomical Union recognizes 88 such regions, and they are not twelve equal slices. The outline of the Aries constellation therefore does not set the boundaries of the Aries sign in a tropical chart.
Earth's axis slowly changes direction over long periods. This gradual shift helps explain why the seasonal sign grid and the background stars no longer line up as they once did. That is a change in how two maps align, not a sudden change to a person's birthday.
Ask which map a claim uses
A skywatching app may tell you which constellation lies behind the Sun. A tropical astrology chart answers which sign contains the Sun's calculated position. Check the map before comparing the two answers. Neither map, by itself, tells you what your personality or future must be.
A few common questions
Did my zodiac sign change because the constellations moved?
Not in a tropical chart. Its signs are measured from the equinox, while constellations are separately defined sky regions.
Sources & further reading
Astrology sources describe their own traditions and methods; they do not establish predictive accuracy. The writing exercises are original Lodestar editorial material.