comments on asteroid albedo, radius

Stellarium · Oct 24, 2024 · f61d86a · f61d86a
1 parent 6a01c77
commit f61d86a
Show file tree

Hide file tree

Showing 4 changed files with 8 additions and 4 deletions.
diff --git a/plugins/SolarSystemEditor/src/SolarSystemEditor.cpp b/plugins/SolarSystemEditor/src/SolarSystemEditor.cpp
@@ -1195,7 +1195,7 @@ SsoElements SolarSystemEditor::readMpcOneLineMinorPlanetElements(const QString &
 	if (q > 30 && semiMajorAxis > 250)
 		objectType = "sednoid";
 
-	// don't save estimated albedo and radius
+	// Loader will estimate albedo and radius
 
 	DiscoveryCircumstances dc = numberedMinorPlanets.value(minorPlanetNumber, DiscoveryCircumstances("",""));
 	if (!dc.first.isEmpty())

diff --git a/src/core/modules/MinorPlanet.cpp b/src/core/modules/MinorPlanet.cpp
@@ -138,7 +138,11 @@ void MinorPlanet::updateEquatorialRadius(void)
 	if (equatorialRadius <= 0.)
 	{
 		if (albedo <= 0.0f)
-			albedo = 0.15f; // assumed
+		{
+			// ESA NEOCC and NASA CNEOS assume albedo between 0.05 and 0.25
+			// https://neo.ssa.esa.int/definitions-assumptions
+			albedo = 0.15f;
+		}
 		// Estimate as described at http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html
 		float diameterKm = 1329.f / std::sqrt(albedo) * std::pow(10.f, -0.2f * absoluteMagnitude);
 		equatorialRadius = 0.5 * diameterKm / AU;

diff --git a/src/core/modules/MinorPlanet.hpp b/src/core/modules/MinorPlanet.hpp
@@ -93,7 +93,7 @@ class MinorPlanet : public Planet
 	//! @param slope Slope parameter G. This is usually [0..1], sometimes slightly outside. Allowed here [-1..2].
 	void setAbsoluteMagnitudeAndSlope(const float magnitude, const float slope);
 
-	//! sets radius based on absolute magnitude.
+	//! sets radius based on absolute magnitude and albedo.
 	void updateEquatorialRadius(void);
 
 	//! renders the subscript in a minor planet IAU provisional designation with HTML.

diff --git a/src/core/modules/SolarSystem.cpp b/src/core/modules/SolarSystem.cpp
@@ -1269,7 +1269,7 @@ bool SolarSystem::loadPlanets(const QString& filePath)
 						    pd.value(secname+"/radius", 0.0).toDouble()/AU,
 						    pd.value(secname+"/oblateness", 0.0).toDouble(),
 						    color, // halo color
-						    pd.value(secname+"/albedo", 0.15f).toFloat(),
+						    pd.value(secname+"/albedo", 0.0f).toFloat(),
 						    pd.value(secname+"/roughness",0.9f).toFloat(),
 						    pd.value(secname+"/tex_map", "nomap.png").toString(),
 						    pd.value(secname+"/normals_map", normalMapName).toString(),