diff --git a/config/rechtesystem.json b/config/rechtesystem.json
index cf111e2..214d133 100644
--- a/config/rechtesystem.json
+++ b/config/rechtesystem.json
@@ -56,6 +56,10 @@
       "label": "Astronomical Conversions",
       "menu_group": "Himmel & Planeten"
     },
+    "blackbody_radiation.php": {
+      "label": "Schwarzkörperstrahlung",
+      "menu_group": "Himmel & Planeten"
+    },
     "tcrb_lightcurve.php": {
       "label": "T CrB Lichtkurve",
       "menu_group": "Himmel & Planeten"
@@ -131,6 +135,7 @@
           "ephemeriden.php",
           "comets.php",
           "astronomical_conversions.php",
+          "blackbody_radiation.php",
           "tcrb_lightcurve.php",
           "solarsystem.php",
           "jupitersystem.php",
diff --git a/public/blackbody_radiation.php b/public/blackbody_radiation.php
new file mode 100644
index 0000000..de8e774
--- /dev/null
+++ b/public/blackbody_radiation.php
@@ -0,0 +1,609 @@
+<?php
+declare(strict_types=1);
+
+ini_set('display_errors', '1');
+error_reporting(E_ALL);
+session_start();
+
+$pageTitle = 'Schwarzkörperstrahlung';
+$headerIntroPre = 'Astronomie-Werkzeuge';
+$headerIntroTitle = 'Schwarzkörperstrahlung';
+$headerIntroSub = 'Planck-Kurve für eine frei wählbare Temperatur als interaktives Diagramm.';
+
+require __DIR__ . '/header.php';
+?>
+
+<style>
+.bb-layout {
+    display: grid;
+    grid-template-columns: minmax(18rem, 24rem) minmax(0, 1fr);
+    gap: 1.5rem;
+    align-items: start;
+}
+
+.bb-panel,
+.bb-chart-card {
+    display: grid;
+    gap: 1rem;
+}
+
+.bb-field-grid {
+    display: grid;
+    gap: 1rem;
+}
+
+.bb-field {
+    display: grid;
+    gap: 0.45rem;
+}
+
+.bb-field label {
+    color: var(--text-dim);
+    font-size: 0.92rem;
+}
+
+.bb-number-row {
+    display: flex;
+    align-items: center;
+    gap: 0.6rem;
+}
+
+.bb-number-row input[type="number"] {
+    width: 100%;
+    padding: 0.72rem 0.8rem;
+    border-radius: var(--radius);
+    border: 1px solid var(--border);
+    background: rgba(255,255,255,0.04);
+    color: var(--text);
+    font-size: 0.96rem;
+    font-family: inherit;
+}
+
+.bb-number-row input[type="number"]:focus,
+.bb-field input[type="range"]:focus {
+    outline: none;
+    border-color: rgba(201, 168, 76, 0.5);
+    box-shadow: 0 0 0 3px rgba(201, 168, 76, 0.1);
+}
+
+.bb-unit {
+    color: var(--text-dim);
+    font-size: 0.88rem;
+    white-space: nowrap;
+}
+
+.bb-field input[type="range"] {
+    width: 100%;
+    accent-color: var(--gold);
+    cursor: pointer;
+}
+
+.bb-hint {
+    color: var(--text-dim);
+    font-size: 0.8rem;
+    line-height: 1.5;
+}
+
+.bb-presets {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.55rem;
+}
+
+.bb-toggle {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.55rem;
+    color: var(--text-dim);
+    font-size: 0.86rem;
+}
+
+.bb-toggle input[type="checkbox"] {
+    accent-color: var(--gold);
+    cursor: pointer;
+}
+
+.bb-field.is-disabled {
+    opacity: 0.55;
+}
+
+.bb-stats {
+    display: grid;
+    grid-template-columns: repeat(3, minmax(0, 1fr));
+    gap: 0.85rem;
+}
+
+.bb-stat {
+    display: grid;
+    gap: 0.2rem;
+    padding: 0.9rem 1rem;
+    border-radius: var(--radius);
+    border: 1px solid var(--border);
+    background: var(--bg-card2);
+}
+
+.bb-stat-label {
+    color: var(--text-dim);
+    font-size: 0.78rem;
+    letter-spacing: 0.04em;
+    text-transform: uppercase;
+}
+
+.bb-stat-value {
+    color: var(--gold-pale);
+    font-size: 1.18rem;
+    font-weight: 600;
+}
+
+.bb-stat-sub {
+    color: var(--text-dim);
+    font-size: 0.8rem;
+}
+
+.bb-curve-wrap {
+    border-radius: var(--radius);
+    border: 1px solid var(--border);
+    background:
+        radial-gradient(circle at top, rgba(201, 168, 76, 0.12), transparent 40%),
+        linear-gradient(180deg, rgba(10, 14, 28, 0.96), rgba(5, 7, 14, 1));
+    padding: 0.75rem;
+}
+
+#bb-canvas {
+    display: block;
+    width: 100%;
+    height: 28rem;
+    border-radius: calc(var(--radius) - 0.2rem);
+}
+
+.bb-note-grid {
+    display: grid;
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+    gap: 1rem;
+}
+
+.bb-note {
+    color: var(--text-dim);
+    font-size: 0.9rem;
+    line-height: 1.6;
+}
+
+.bb-note strong {
+    color: var(--text);
+}
+
+@media (max-width: 980px) {
+    .bb-layout {
+        grid-template-columns: 1fr;
+    }
+
+    .bb-stats,
+    .bb-note-grid {
+        grid-template-columns: 1fr;
+    }
+
+    #bb-canvas {
+        height: 22rem;
+    }
+}
+</style>
+
+<div class="bb-layout">
+    <section class="card bb-panel">
+        <div>
+            <h2>Parameter</h2>
+            <p class="bb-hint">Die Kurve zeigt die spektrale Strahlungsdichte eines idealen Schwarzkörpers nach dem planckschen Strahlungsgesetz.</p>
+        </div>
+
+        <div class="bb-field-grid">
+            <div class="bb-field">
+                <label for="bbTemperature">Temperatur</label>
+                <div class="bb-number-row">
+                    <input id="bbTemperature" type="number" min="100" max="40000" step="10" value="5778">
+                    <span class="bb-unit">K</span>
+                </div>
+                <input id="bbTemperatureRange" type="range" min="100" max="40000" step="10" value="5778">
+                <div class="bb-hint">Typische Bereiche: Glühlampe ~ 2.700 K, Sonne ~ 5.778 K, heißer Stern > 10.000 K.</div>
+            </div>
+
+            <div class="bb-field">
+                <label for="bbMaxWavelength">Diagrammbereich</label>
+                <div class="bb-number-row">
+                    <input id="bbMaxWavelength" type="number" min="1000" max="10000" step="100" value="3000">
+                    <span class="bb-unit">nm</span>
+                </div>
+                <input id="bbMaxWavelengthRange" type="range" min="1000" max="10000" step="100" value="3000">
+                <div class="bb-hint">Das Diagramm beginnt bei 100 nm und endet beim hier gewählten Maximalwert.</div>
+            </div>
+
+            <div class="bb-field is-disabled" id="bbYAxisField">
+                <label for="bbYAxisMax">Y-Achse</label>
+                <label class="bb-toggle" for="bbYAxisAuto">
+                    <input id="bbYAxisAuto" type="checkbox" checked>
+                    <span>Automatisch skalieren</span>
+                </label>
+                <div class="bb-number-row">
+                    <input id="bbYAxisMax" type="number" min="1000000" max="400000000000000000" step="1000000" value="10000000000000" disabled>
+                    <span class="bb-unit">W·sr⁻¹·m⁻³</span>
+                </div>
+                <input id="bbYAxisMaxRange" type="range" min="1000000" max="400000000000000000" step="1000000" value="10000000000000" disabled>
+                <div class="bb-hint">Wenn Auto aus ist, legst du hier den Maximalwert der y-Achse selbst fest.</div>
+            </div>
+        </div>
+
+        <div>
+            <div class="bb-hint" style="margin-bottom:0.5rem;">Beispiele</div>
+            <div class="bb-presets">
+                <button type="button" class="btn btn-secondary btn-sm" data-temp="300">Erde ~ 300 K</button>
+                <button type="button" class="btn btn-secondary btn-sm" data-temp="2700">Glühlampe</button>
+                <button type="button" class="btn btn-secondary btn-sm" data-temp="5778">Sonne</button>
+                <button type="button" class="btn btn-secondary btn-sm" data-temp="10000">Heißer Stern</button>
+            </div>
+        </div>
+    </section>
+
+    <section class="bb-chart-card">
+        <div class="bb-stats">
+            <div class="bb-stat">
+                <span class="bb-stat-label">Wellenlängenmaximum</span>
+                <span class="bb-stat-value" id="bbPeakNm">–</span>
+                <span class="bb-stat-sub" id="bbPeakRegion">–</span>
+            </div>
+            <div class="bb-stat">
+                <span class="bb-stat-label">Stefan-Boltzmann</span>
+                <span class="bb-stat-value" id="bbFlux">–</span>
+                <span class="bb-stat-sub">Gesamtleistung pro Fläche</span>
+            </div>
+            <div class="bb-stat">
+                <span class="bb-stat-label">Relative Farbwirkung</span>
+                <span class="bb-stat-value" id="bbColorLabel">–</span>
+                <span class="bb-stat-sub">grob aus dem Peak-Bereich</span>
+            </div>
+        </div>
+
+        <div class="card">
+            <h2>Planck-Kurve</h2>
+            <div class="bb-curve-wrap">
+                <canvas id="bb-canvas" aria-label="Diagramm der Schwarzkörperstrahlung"></canvas>
+            </div>
+        </div>
+
+        <div class="bb-note-grid">
+            <div class="card bb-note">
+                <strong>Was zeigt die Kurve?</strong><br>
+                Auf der x-Achse steht die Wellenlänge in Nanometern, auf der y-Achse die spektrale Strahlungsdichte. Höhere Temperaturen verschieben das Maximum zu kleineren Wellenlängen.
+            </div>
+            <div class="card bb-note">
+                <strong>Wichtige Gesetze</strong><br>
+                Das Wiensche Verschiebungsgesetz liefert die Lage des Maximums, das Stefan-Boltzmann-Gesetz die gesamte abgestrahlte Leistung über alle Wellenlängen.
+            </div>
+        </div>
+    </section>
+</div>
+
+<script>
+(function () {
+    const PLANCK_H = 6.62607015e-34;
+    const LIGHT_C = 2.99792458e8;
+    const BOLTZMANN_K = 1.380649e-23;
+    const STEFAN_BOLTZMANN = 5.670374419e-8;
+    const WIEN_DISPLACEMENT_NM_K = 2.897771955e6;
+    const MIN_WAVELENGTH_NM = 100;
+
+    const temperatureInput = document.getElementById('bbTemperature');
+    const temperatureRange = document.getElementById('bbTemperatureRange');
+    const maxWavelengthInput = document.getElementById('bbMaxWavelength');
+    const maxWavelengthRange = document.getElementById('bbMaxWavelengthRange');
+    const yAxisField = document.getElementById('bbYAxisField');
+    const yAxisAutoInput = document.getElementById('bbYAxisAuto');
+    const yAxisMaxInput = document.getElementById('bbYAxisMax');
+    const yAxisMaxRange = document.getElementById('bbYAxisMaxRange');
+    const peakNmOutput = document.getElementById('bbPeakNm');
+    const peakRegionOutput = document.getElementById('bbPeakRegion');
+    const fluxOutput = document.getElementById('bbFlux');
+    const colorLabelOutput = document.getElementById('bbColorLabel');
+    const canvas = document.getElementById('bb-canvas');
+    const ctx = canvas.getContext('2d');
+
+    function syncPair(primary, secondary, onChange) {
+        primary.addEventListener('input', function () {
+            secondary.value = primary.value;
+            onChange();
+        });
+        secondary.addEventListener('input', function () {
+            primary.value = secondary.value;
+            onChange();
+        });
+    }
+
+    function clamp(value, min, max) {
+        return Math.min(max, Math.max(min, value));
+    }
+
+    function updateYAxisControls() {
+        const isAuto = yAxisAutoInput.checked;
+        yAxisMaxInput.disabled = isAuto;
+        yAxisMaxRange.disabled = isAuto;
+        yAxisField.classList.toggle('is-disabled', isAuto);
+    }
+
+    function planckSpectralRadiance(lambdaMeters, temperatureKelvin) {
+        const exponent = (PLANCK_H * LIGHT_C) / (lambdaMeters * BOLTZMANN_K * temperatureKelvin);
+        if (!Number.isFinite(exponent) || exponent > 700) {
+            return 0;
+        }
+
+        const numerator = 2 * PLANCK_H * Math.pow(LIGHT_C, 2);
+        const denominator = Math.pow(lambdaMeters, 5) * (Math.exp(exponent) - 1);
+        return numerator / denominator;
+    }
+
+    function formatGermanNumber(value, fractionDigits) {
+        return new Intl.NumberFormat('de-DE', {
+            minimumFractionDigits: fractionDigits,
+            maximumFractionDigits: fractionDigits
+        }).format(value);
+    }
+
+    function formatScientific(value) {
+        if (!Number.isFinite(value) || value <= 0) {
+            return '0';
+        }
+
+        const exponent = Math.floor(Math.log10(value));
+        const mantissa = value / Math.pow(10, exponent);
+        return formatGermanNumber(mantissa, 2) + ' × 10^' + exponent;
+    }
+
+    function describePeakRegion(peakNm) {
+        if (peakNm < 380) {
+            return 'Maximum im Ultraviolett';
+        }
+        if (peakNm < 450) {
+            return 'Maximum im violett-blauen Bereich';
+        }
+        if (peakNm < 495) {
+            return 'Maximum im blauen Bereich';
+        }
+        if (peakNm < 570) {
+            return 'Maximum im grün-gelben Bereich';
+        }
+        if (peakNm < 590) {
+            return 'Maximum im gelben Bereich';
+        }
+        if (peakNm < 620) {
+            return 'Maximum im orangefarbenen Bereich';
+        }
+        if (peakNm < 750) {
+            return 'Maximum im roten Bereich';
+        }
+        return 'Maximum im Infrarot';
+    }
+
+    function describeColor(peakNm) {
+        if (peakNm < 380) {
+            return 'bläulich bis UV-dominiert';
+        }
+        if (peakNm < 500) {
+            return 'bläulich';
+        }
+        if (peakNm < 570) {
+            return 'weißlich';
+        }
+        if (peakNm < 620) {
+            return 'gelblich';
+        }
+        if (peakNm < 750) {
+            return 'orange bis rötlich';
+        }
+        return 'rot bis infrarotdominiert';
+    }
+
+    function drawVisibleBand(plotLeft, plotTop, plotWidth, plotHeight, xMin, xMax) {
+        const visibleStart = Math.max(380, xMin);
+        const visibleEnd = Math.min(750, xMax);
+        if (visibleEnd <= visibleStart) {
+            return;
+        }
+
+        const startX = plotLeft + ((visibleStart - xMin) / (xMax - xMin)) * plotWidth;
+        const endX = plotLeft + ((visibleEnd - xMin) / (xMax - xMin)) * plotWidth;
+        const gradient = ctx.createLinearGradient(startX, 0, endX, 0);
+        gradient.addColorStop(0.00, 'rgba(102, 0, 255, 0.30)');
+        gradient.addColorStop(0.17, 'rgba(0, 90, 255, 0.30)');
+        gradient.addColorStop(0.34, 'rgba(0, 200, 255, 0.30)');
+        gradient.addColorStop(0.50, 'rgba(0, 255, 120, 0.25)');
+        gradient.addColorStop(0.67, 'rgba(255, 230, 0, 0.25)');
+        gradient.addColorStop(0.83, 'rgba(255, 140, 0, 0.28)');
+        gradient.addColorStop(1.00, 'rgba(255, 40, 0, 0.28)');
+
+        ctx.fillStyle = gradient;
+        ctx.fillRect(startX, plotTop, endX - startX, plotHeight);
+    }
+
+    function renderChart() {
+        const temperature = clamp(Number(temperatureInput.value) || 0, 100, 40000);
+        const maxWavelengthNm = clamp(Number(maxWavelengthInput.value) || 0, 1000, 10000);
+        temperatureInput.value = String(temperature);
+        temperatureRange.value = String(temperature);
+        maxWavelengthInput.value = String(maxWavelengthNm);
+        maxWavelengthRange.value = String(maxWavelengthNm);
+
+        const peakNm = WIEN_DISPLACEMENT_NM_K / temperature;
+        const totalFlux = STEFAN_BOLTZMANN * Math.pow(temperature, 4);
+
+        peakNmOutput.textContent = formatGermanNumber(peakNm, peakNm < 100 ? 1 : 0) + ' nm';
+        peakRegionOutput.textContent = describePeakRegion(peakNm);
+        fluxOutput.textContent = formatScientific(totalFlux) + ' W/m²';
+        colorLabelOutput.textContent = describeColor(peakNm);
+
+        const ratio = Math.min(window.devicePixelRatio || 1, 2);
+        const width = canvas.clientWidth;
+        const height = canvas.clientHeight;
+        canvas.width = Math.round(width * ratio);
+        canvas.height = Math.round(height * ratio);
+        ctx.setTransform(ratio, 0, 0, ratio, 0, 0);
+        ctx.clearRect(0, 0, width, height);
+
+        const padding = { top: 20, right: 22, bottom: 48, left: 78 };
+        const plotLeft = padding.left;
+        const plotTop = padding.top;
+        const plotWidth = width - padding.left - padding.right;
+        const plotHeight = height - padding.top - padding.bottom;
+        const xMin = MIN_WAVELENGTH_NM;
+        const xMax = maxWavelengthNm;
+
+        const samples = Math.max(320, Math.floor(plotWidth));
+        const points = [];
+        let dataMaxRadiance = 0;
+
+        for (let index = 0; index <= samples; index += 1) {
+            const wavelengthNm = xMin + ((xMax - xMin) * index / samples);
+            const radiance = planckSpectralRadiance(wavelengthNm * 1e-9, temperature);
+            if (radiance > dataMaxRadiance) {
+                dataMaxRadiance = radiance;
+            }
+            points.push({ wavelengthNm, radiance });
+        }
+
+        let maxRadiance = dataMaxRadiance;
+        if (!yAxisAutoInput.checked) {
+            const manualMaxRadiance = Number(yAxisMaxInput.value) || 0;
+            if (Number.isFinite(manualMaxRadiance) && manualMaxRadiance > 0) {
+                maxRadiance = manualMaxRadiance;
+            }
+        }
+        maxRadiance = Math.max(maxRadiance, dataMaxRadiance * 0.05, 1);
+
+        drawVisibleBand(plotLeft, plotTop, plotWidth, plotHeight, xMin, xMax);
+
+        ctx.strokeStyle = 'rgba(255,255,255,0.08)';
+        ctx.lineWidth = 1;
+        ctx.font = '11px Georgia, serif';
+        ctx.fillStyle = 'rgba(220, 226, 244, 0.72)';
+
+        const xTicks = [100, 250, 500, 750, 1000, 1500, 2000, 3000, 5000, 8000, 10000].filter(function (tick) {
+            return tick >= xMin && tick <= xMax;
+        });
+        xTicks.forEach(function (tick) {
+            const x = plotLeft + ((tick - xMin) / (xMax - xMin)) * plotWidth;
+            ctx.beginPath();
+            ctx.moveTo(x, plotTop);
+            ctx.lineTo(x, plotTop + plotHeight);
+            ctx.stroke();
+            ctx.textAlign = 'center';
+            ctx.textBaseline = 'top';
+            ctx.fillText(String(tick), x, plotTop + plotHeight + 8);
+        });
+
+        const yTicks = 5;
+        for (let tick = 0; tick <= yTicks; tick += 1) {
+            const value = maxRadiance * tick / yTicks;
+            const y = plotTop + plotHeight - (tick / yTicks) * plotHeight;
+            ctx.beginPath();
+            ctx.moveTo(plotLeft, y);
+            ctx.lineTo(plotLeft + plotWidth, y);
+            ctx.stroke();
+            ctx.textAlign = 'right';
+            ctx.textBaseline = 'middle';
+            ctx.fillText(formatScientific(value), plotLeft - 10, y);
+        }
+
+        ctx.strokeStyle = 'rgba(255,255,255,0.22)';
+        ctx.lineWidth = 1.2;
+        ctx.beginPath();
+        ctx.moveTo(plotLeft, plotTop);
+        ctx.lineTo(plotLeft, plotTop + plotHeight);
+        ctx.lineTo(plotLeft + plotWidth, plotTop + plotHeight);
+        ctx.stroke();
+
+        const areaGradient = ctx.createLinearGradient(0, plotTop, 0, plotTop + plotHeight);
+        areaGradient.addColorStop(0, 'rgba(201, 168, 76, 0.38)');
+        areaGradient.addColorStop(1, 'rgba(201, 168, 76, 0.03)');
+
+        ctx.beginPath();
+        points.forEach(function (point, index) {
+            const x = plotLeft + ((point.wavelengthNm - xMin) / (xMax - xMin)) * plotWidth;
+            const y = plotTop + plotHeight - ((point.radiance / maxRadiance) * plotHeight);
+            if (index === 0) {
+                ctx.moveTo(x, y);
+                return;
+            }
+            ctx.lineTo(x, y);
+        });
+        ctx.lineTo(plotLeft + plotWidth, plotTop + plotHeight);
+        ctx.lineTo(plotLeft, plotTop + plotHeight);
+        ctx.closePath();
+        ctx.fillStyle = areaGradient;
+        ctx.fill();
+
+        ctx.beginPath();
+        points.forEach(function (point, index) {
+            const x = plotLeft + ((point.wavelengthNm - xMin) / (xMax - xMin)) * plotWidth;
+            const y = plotTop + plotHeight - ((point.radiance / maxRadiance) * plotHeight);
+            if (index === 0) {
+                ctx.moveTo(x, y);
+                return;
+            }
+            ctx.lineTo(x, y);
+        });
+        ctx.strokeStyle = '#f0d47b';
+        ctx.lineWidth = 2.4;
+        ctx.stroke();
+
+        if (peakNm >= xMin && peakNm <= xMax) {
+            const peakX = plotLeft + ((peakNm - xMin) / (xMax - xMin)) * plotWidth;
+            ctx.beginPath();
+            ctx.moveTo(peakX, plotTop);
+            ctx.lineTo(peakX, plotTop + plotHeight);
+            ctx.strokeStyle = 'rgba(79, 195, 216, 0.95)';
+            ctx.lineWidth = 1.4;
+            ctx.setLineDash([6, 5]);
+            ctx.stroke();
+            ctx.setLineDash([]);
+
+            ctx.fillStyle = '#4fc3d8';
+            ctx.textAlign = 'left';
+            ctx.textBaseline = 'top';
+            ctx.fillText('λmax', Math.min(peakX + 6, plotLeft + plotWidth - 42), plotTop + 6);
+        }
+
+        ctx.fillStyle = 'rgba(240, 244, 255, 0.85)';
+        ctx.textAlign = 'center';
+        ctx.textBaseline = 'bottom';
+        ctx.fillText('Wellenlänge in nm', plotLeft + plotWidth / 2, height - 10);
+
+        ctx.save();
+        ctx.translate(18, plotTop + plotHeight / 2);
+        ctx.rotate(-Math.PI / 2);
+        ctx.textAlign = 'center';
+        ctx.textBaseline = 'top';
+        ctx.fillText('Spektrale Strahlungsdichte Bλ', 0, 0);
+        ctx.restore();
+    }
+
+    syncPair(temperatureInput, temperatureRange, renderChart);
+    syncPair(maxWavelengthInput, maxWavelengthRange, renderChart);
+    syncPair(yAxisMaxInput, yAxisMaxRange, renderChart);
+
+    yAxisAutoInput.addEventListener('change', function () {
+        updateYAxisControls();
+        renderChart();
+    });
+
+    document.querySelectorAll('[data-temp]').forEach(function (button) {
+        button.addEventListener('click', function () {
+            const value = button.getAttribute('data-temp') || '5778';
+            temperatureInput.value = value;
+            temperatureRange.value = value;
+            renderChart();
+        });
+    });
+
+    window.addEventListener('resize', renderChart);
+    updateYAxisControls();
+    renderChart();
+})();
+</script>
+
+<?php require __DIR__ . '/footer.php'; ?>
diff --git a/public/header.php b/public/header.php
index f0c66e8..50b0d6c 100644
--- a/public/header.php
+++ b/public/header.php
@@ -176,6 +176,7 @@ $menuGroups = [
         'links' => [
             ['href' => 'tcrb_lightcurve.php',          'label' => 'T CrB Lichtkurve'],
             ['href' => 'astronomical_conversions.php',  'label' => 'Astronomical Conversions'],
+            ['href' => 'blackbody_radiation.php',       'label' => 'Schwarzkörperstrahlung'],
             ['href' => 'geocron/index.php',             'label' => 'Geocron'],
             ['href' => 'geocron3d.php',                 'label' => 'Geocron 3D'],
             ['href' => 'geocron3d_C.php',               'label' => 'Geocron 3D Cesium'],