Physical Size From Angular Size and Distance
Inverseplanartransversediskangulardiameteratanprojection,0≤θ<180,no sphericalarcsinlimb/distanceinference. Actual independent model/unit/frame/epoch/calibration and applicable measurement established;not precise ephemeris,forecast,geodesy operation,identity or safety approval.
Description
An angular diameter can be converted to the transverse diameter of a planar disk at a known center distance.
An angular diameter can be converted to the transverse diameter of a planar disk at a known center distance.1
This tool uses tangent geometry and matching distance units; a spherical body’s visible limb follows a different relation.
When to use Physical Size From Angular Size and Distance
Use this tool to apply the stated physical size from angular size and distance operation with an explicit input and unit basis.
How to use Physical Size From Angular Size and Distance and how it works
- Establish the measurement basis and units described above.
- Enter actualCenterDistance, actualAngularDiameterDegrees and run the tool.
- Read result.value using the output meanings below.
- If input is rejected, correct the stated type, range, ordering or alignment issue and rerun; review successful results under the declared convention.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualCenterDistance | Center Distance. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; strictly positive; further conditions in the algorithm |
| actualAngularDiameterDegrees | Angular Diameter Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; nonnegative; further conditions in the algorithm |
Require positive center distance and angular diameter from zero inclusive to 180 degrees exclusive. Compute twice the distance times the tangent of half the angular diameter.
diameter = 2 × distance × tan(angularDiameter/2) Apply the declared units, ordering and branch conditions.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the declared output fields. | object |
| result.value | Planar transverse diameter in the center-distance unit. | number |
{
"input": {
"actualCenterDistance": 1,
"actualAngularDiameterDegrees": 90
},
"output": {
"result": {
"value": 1.9999999999999998
}
}
}Limitations and assumptions
The output applies the declared operation to the values you supply. Establish the measurement basis, units, coefficients and any caller-selected rules before interpreting it. The tool does not independently collect or verify observations or decide whether a model or reference applies.
Supply explicit required fields with the documented types and dense aligned arrays. Unknown fields, wrong types and nonfinite numbers are rejected. Branch-specific constraints are explained above. A returned boolean, signed difference or tied result follows the stated convention; an input error instead means the required input contract was not satisfied. Very large inputs or outputs may be rejected by shared resource limits.
Alternative or Complementary methods
For a related operation, use Angular Size From Diameter and Distance. A planar disk’s angular diameter follows exact tangent geometry at its center distance.
For a related operation, use Small Angle Formula Arcseconds Calculator. The small-angle formula relates a transverse physical size to an angular size when the size-to-distance ratio is small.
References
Similar or alternative tools
- Angular Size From Diameter and Distance
A planar disk’s angular diameter follows exact tangent geometry at its center distance.
- Small Angle Formula Arcseconds Calculator
The small-angle formula relates a transverse physical size to an angular size when the size-to-distance ratio is small.