What it is
A planet is retrograde when, seen from Earth, it appears to move backward through the zodiac for a while before resuming its usual direction. Nothing actually reverses. It is a perspective effect: Earth and the other planet orbit the Sun at different speeds, and when one overtakes the other, the slower one seems to slide backward against the stars — the way a car you pass on the motorway appears to drift behind you.
Every planet except the Sun and Moon goes retrograde. Mercury does it three or four times a year for about three weeks each; Venus and Mars less often; the outer planets for months at a stretch, so that any given chart has a fair chance of a retrograde planet or two.
In astrological tradition a retrograde planet is read as turned inward: its themes are revisited rather than advanced. Mercury retrograde, the famous one, is associated with rereading, rescheduling and misunderstandings — as a tone, not a law.
Why it matters for daily reflection
Retrograde periods are useful mainly as a permission slip. They suggest a season for looking back — finishing things, rereading old notes, calling the friend you let drift — instead of pushing forward. Whether or not the planet has anything to do with it, "this is a reviewing week" is a good prompt.
The trap is the other direction: blaming a lost email on Mercury. Retrograde does not cause anything. If you notice more friction during one, write it down; if you don't, write that down too. A retrograde that never seems to matter is honest data.
In Lunara
Retrograde planets appear in your basic natal chart if any were retrograde at your birth. Current retrogrades belong to the wider set of transits that Lunara+ includes beyond the daily Moon. In either case, the practice is the same: one Signal, one small step, an evening Echo — and a Resonance Map that shows, over days, whether the retrograde season felt like anything at all.