An ingress is the moment the Sun, the Moon, or a planet enters a new zodiac sign. In the tropical zodiac each sign spans 30 degrees of ecliptic longitude, so an ingress happens when a body’s calculated longitude crosses a multiple of 30 degrees, for example from the last minutes of Gemini into 0° Cancer. The word comes from the Latin for “entering”. It names a boundary crossing on a reference circle, not something that happens to the body itself.
Ingresses come at very different speeds. The Moon changes sign every two to three days, Saturn spends about two and a half years in each sign, and Pluto stays for more than a decade. During a retrograde loop a planet can cross the same boundary three times: forward, back, and forward again.
The astrology calendars list ingresses as sign changes for all ten bodies, each with its UTC time. A retrograde crossing appears as a move back into the earlier sign. When the Sun enters Aries, Cancer, Libra, or Capricorn, the calendars name the event as an equinox or solstice. The sky explorer shows every body’s sign at a moment you choose, and the sign-boundary guide explains why a birthday near a change needs a birth time.
A related turning point is the station, when a planet seems to pause before it changes direction. For the ongoing relationship between a moving body and a birth chart, see transit.
In a chart
Suppose a daily table shows Mars at 29°40′ Leo on one day and 0°15′ Virgo on the next. Mars made its ingress into Virgo between those two rows, and only a search between them gives the exact minute. A birth chart works the same way in reverse: it records the sign each body occupied at the moment of birth. When a planet sits within a few arcminutes of a boundary, a small error in the recorded birth time can move it into the next or the previous sign.
Where you see it on Astrologican
These free tools and pages calculate or list it, so you can see it in a real result.