Why Signs Don't Apply to Right Ascension
Select the Equatorial plane in Aquila or Compass and the zodiac signs disappear. Not relabelled, not converted — gone. Positions come back as plain degrees of right ascension, and no sign name appears anywhere in the output.
This is deliberate, and this page is why.
Signs live on one particular circle
Go back to the definition. A sign is a 30° division of celestial longitude, measured along the ecliptic, starting from the vernal equinox. Aries is 0°–30° of that circle; Taurus is 30°–60° of it.
The signs are not an abstract twelvefold division that can be laid over any scale that happens to run from 0 to 360. They are marks on one specific great circle, and their whole meaning is where they fall on that circle.
Right ascension runs around a different great circle, tilted 23.4° away. It starts at the same point — both scales count from the vernal equinox — and then, as the vernal equinox page showed, immediately parts company.
What a sign name on a right ascension would claim
Suppose the applications did divide right ascension into twelve 30° blocks and call the second one Taurus. What would that assert?
It would assert that a body at 45° of right ascension is "in Taurus". But the body at 45° of right ascension is not at 45° of celestial longitude — as the previous page established, the two readings differ, sometimes by degrees. A body genuinely in Taurus can read a right ascension in the neighbouring block, and a body in the neighbouring sign can read one inside it.
The label would be wrong in the only sense a label can be wrong: it would name a region the body is not in.
Some people do it anyway
It should be said plainly that this is not a settled universal.
There is a practice of applying the twelve sign names to right ascension in a symbolic sense — treating the twelvefold division as a pattern that can be imposed on any full circle, and reading meaning into the block a body falls in regardless of which circle is being divided.
The Rhythm Seven applications do not do this. The reason is practical rather than
doctrinal: it causes confusion. A reader who sees 00°Lib00' in an output
reasonably takes it to mean the body is at 0° Libra, and under the equatorial plane
that is not what it would mean. The label invites a zodiacal reading of a
measurement that is not zodiacal, and there is no way to display it that reliably
prevents the mistake.
Withholding it is the honest option. If you want a sign position, ask for one — by selecting the Ecliptic plane, which is the frame signs are defined in.
What the applications actually do
The behaviour is consistent across both products, and the rule behind it is worth stating on its own: a withheld position is replaced, not simply removed.
Under the Equatorial plane no sign name appears anywhere — not in a table, not on a wheel. What appears instead is the same body's position as a plain angle around the full circle, which is a position in the frame you actually asked for. You never end up with output that reports no position at all.
The general principle
This is worth extracting, because it applies well beyond signs.
A coordinate carries its reference plane with it. Vocabulary defined in one frame does not transfer to another merely because both are measured in degrees and both run from 0 to 360.
The same caution applies to celestial latitude and declination, which are routinely confused for exactly this reason: both are "how far off the plane", both are in degrees, both run to ±90°, and they are different numbers for the same body. And it applies to the sign labels here.
Two scales looking alike is not the same as two scales meaning alike.
What comes next
The equatorial frame withholds something. It also offers something the ecliptic frame cannot express at all.