diff --git a/.prettierignore b/.prettierignore
index d913489d9fd2..c4fbdbbe4e0c 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -17,6 +17,7 @@
 !**/*.css
 !**/*.html
 !**/*.md
+!**/*.ts
 
 # Re-ignore a few things caught above
 **/*.min.js
diff --git a/CHANGES.md b/CHANGES.md
index b42825be19c2..ec1fe5574fd7 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -11,6 +11,8 @@
 - Improved `MaterialProperty` JSDoc and TypeScript type definitions, which were missing the ability to take primitive types in addition to Property instances in their constructor.
 - Fixed `EllipsoidGeodesic` JSDoc and TypeScript type definitions which incorrectly listed `result` as required.
 - Fixed a bug with handling of PixelFormat's flipY. [#8893](https://github.com/CesiumGS/cesium/pull/8893)
+- Fixed JSDoc and TypeScript type definitions for all `ImageryProvider` types, which were missing `defaultNightAlpha` and `defaultDayAlpha` properties.
+- Fixed JSDoc and TypeScript type definitions for `Viewer` options parameter, which was incorrectly listed as required.
 - Fixed a memory leak where some 3D Tiles requests were being unintentionally retained after the requests were cancelled. [#8843](https://github.com/CesiumGS/cesium/pull/8843)
 
 ### 1.70.0 - 2020-06-01
diff --git a/Source/Core/HeadingPitchRange.js b/Source/Core/HeadingPitchRange.js
index 974620261628..15741102e771 100644
--- a/Source/Core/HeadingPitchRange.js
+++ b/Source/Core/HeadingPitchRange.js
@@ -17,6 +17,7 @@ function HeadingPitchRange(heading, pitch, range) {
   /**
    * Heading is the rotation from the local north direction where a positive angle is increasing eastward.
    * @type {Number}
+   * @default 0.0
    */
   this.heading = defaultValue(heading, 0.0);
 
@@ -24,12 +25,14 @@ function HeadingPitchRange(heading, pitch, range) {
    * Pitch is the rotation from the local xy-plane. Positive pitch angles
    * are above the plane. Negative pitch angles are below the plane.
    * @type {Number}
+   * @default 0.0
    */
   this.pitch = defaultValue(pitch, 0.0);
 
   /**
    * Range is the distance from the center of the local frame.
    * @type {Number}
+   * @default 0.0
    */
   this.range = defaultValue(range, 0.0);
 }
diff --git a/Source/Core/HeadingPitchRoll.js b/Source/Core/HeadingPitchRoll.js
index cb037c3c41ce..acfd5c82896c 100644
--- a/Source/Core/HeadingPitchRoll.js
+++ b/Source/Core/HeadingPitchRoll.js
@@ -15,8 +15,23 @@ import CesiumMath from "./Math.js";
  * @param {Number} [roll=0.0] The roll component in radians.
  */
 function HeadingPitchRoll(heading, pitch, roll) {
+  /**
+   * Gets or sets the heading.
+   * @type {Number}
+   * @default 0.0
+   */
   this.heading = defaultValue(heading, 0.0);
+  /**
+   * Gets or sets the pitch.
+   * @type {Number}
+   * @default 0.0
+   */
   this.pitch = defaultValue(pitch, 0.0);
+  /**
+   * Gets or sets the roll.
+   * @type {Number}
+   * @default 0.0
+   */
   this.roll = defaultValue(roll, 0.0);
 }
 
diff --git a/Source/DataSources/NodeTransformationProperty.js b/Source/DataSources/NodeTransformationProperty.js
index 64ef8714a2c8..f5070203484f 100644
--- a/Source/DataSources/NodeTransformationProperty.js
+++ b/Source/DataSources/NodeTransformationProperty.js
@@ -13,9 +13,9 @@ var defaultNodeTransformation = new TranslationRotationScale();
  * @constructor
  *
  * @param {Object} [options] Object with the following properties:
- * @param {Property} [options.translation=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the (x, y, z) translation to apply to the node.
- * @param {Property} [options.rotation=Quaternion.IDENTITY] A {@link Quaternion} Property specifying the (x, y, z, w) rotation to apply to the node.
- * @param {Property} [options.scale=new Cartesian3(1.0, 1.0, 1.0)] A {@link Cartesian3} Property specifying the (x, y, z) scaling to apply to the node.
+ * @param {Property|Cartesian3} [options.translation=Cartesian3.ZERO] A {@link Cartesian3} Property specifying the (x, y, z) translation to apply to the node.
+ * @param {Property|Quaternion} [options.rotation=Quaternion.IDENTITY] A {@link Quaternion} Property specifying the (x, y, z, w) rotation to apply to the node.
+ * @param {Property|Cartesian3} [options.scale=new Cartesian3(1.0, 1.0, 1.0)] A {@link Cartesian3} Property specifying the (x, y, z) scaling to apply to the node.
  */
 function NodeTransformationProperty(options) {
   options = defaultValue(options, defaultValue.EMPTY_OBJECT);
diff --git a/Source/DataSources/PositionPropertyArray.js b/Source/DataSources/PositionPropertyArray.js
index b4c04259f138..1067d4914735 100644
--- a/Source/DataSources/PositionPropertyArray.js
+++ b/Source/DataSources/PositionPropertyArray.js
@@ -7,7 +7,7 @@ import ReferenceFrame from "../Core/ReferenceFrame.js";
 import Property from "./Property.js";
 
 /**
- * A {@link PositionProperty} whose value is an array whose items are the computed value
+ * A {@link Property} whose value is an array whose items are the computed value
  * of other PositionProperty instances.
  *
  * @alias PositionPropertyArray
diff --git a/Source/DataSources/VelocityOrientationProperty.js b/Source/DataSources/VelocityOrientationProperty.js
index 6c4c06705590..78c49d7c647c 100644
--- a/Source/DataSources/VelocityOrientationProperty.js
+++ b/Source/DataSources/VelocityOrientationProperty.js
@@ -16,7 +16,7 @@ import VelocityVectorProperty from "./VelocityVectorProperty.js";
  * @alias VelocityOrientationProperty
  * @constructor
  *
- * @param {Property} [position] The position property used to compute the orientation.
+ * @param {PositionProperty} [position] The position property used to compute the orientation.
  * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid used to determine which way is up.
  *
  * @example
diff --git a/Source/DataSources/VelocityVectorProperty.js b/Source/DataSources/VelocityVectorProperty.js
index 8c718bc68353..b5506059e849 100644
--- a/Source/DataSources/VelocityVectorProperty.js
+++ b/Source/DataSources/VelocityVectorProperty.js
@@ -13,7 +13,7 @@ import Property from "./Property.js";
  * @alias VelocityVectorProperty
  * @constructor
  *
- * @param {Property} [position] The position property used to compute the velocity.
+ * @param {PositionProperty} [position] The position property used to compute the velocity.
  * @param {Boolean} [normalize=true] Whether to normalize the computed velocity vector.
  *
  * @example
diff --git a/Source/Scene/ArcGisMapServerImageryProvider.js b/Source/Scene/ArcGisMapServerImageryProvider.js
index b982130e43b2..240154ae2e4b 100644
--- a/Source/Scene/ArcGisMapServerImageryProvider.js
+++ b/Source/Scene/ArcGisMapServerImageryProvider.js
@@ -101,16 +101,34 @@ function ArcGisMapServerImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -119,7 +137,7 @@ function ArcGisMapServerImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -127,7 +145,7 @@ function ArcGisMapServerImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -136,7 +154,7 @@ function ArcGisMapServerImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -144,7 +162,7 @@ function ArcGisMapServerImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -524,7 +542,7 @@ Object.defineProperties(ArcGisMapServerImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link ArcGisMapServerImageryProvider#ready} returns true.
    * @memberof ArcGisMapServerImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/BingMapsImageryProvider.js b/Source/Scene/BingMapsImageryProvider.js
index 2e458a5f2e3c..16bedbb4bb3a 100644
--- a/Source/Scene/BingMapsImageryProvider.js
+++ b/Source/Scene/BingMapsImageryProvider.js
@@ -80,16 +80,34 @@ function BingMapsImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -98,7 +116,7 @@ function BingMapsImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -106,7 +124,7 @@ function BingMapsImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -115,7 +133,7 @@ function BingMapsImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -123,7 +141,7 @@ function BingMapsImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default 1.0
    */
   this.defaultGamma = 1.0;
@@ -404,7 +422,7 @@ Object.defineProperties(BingMapsImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link BingMapsImageryProvider#ready} returns true.
    * @memberof BingMapsImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/GoogleEarthEnterpriseImageryProvider.js b/Source/Scene/GoogleEarthEnterpriseImageryProvider.js
index ed6054161d42..54013f15f698 100644
--- a/Source/Scene/GoogleEarthEnterpriseImageryProvider.js
+++ b/Source/Scene/GoogleEarthEnterpriseImageryProvider.js
@@ -100,16 +100,34 @@ function GoogleEarthEnterpriseImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -118,7 +136,7 @@ function GoogleEarthEnterpriseImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -126,7 +144,7 @@ function GoogleEarthEnterpriseImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -135,7 +153,7 @@ function GoogleEarthEnterpriseImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -143,7 +161,7 @@ function GoogleEarthEnterpriseImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -315,7 +333,7 @@ Object.defineProperties(GoogleEarthEnterpriseImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link GoogleEarthEnterpriseImageryProvider#ready} returns true.
    * @memberof GoogleEarthEnterpriseImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/GoogleEarthEnterpriseMapsProvider.js b/Source/Scene/GoogleEarthEnterpriseMapsProvider.js
index 4f3150017bc4..5ac25bf96b81 100644
--- a/Source/Scene/GoogleEarthEnterpriseMapsProvider.js
+++ b/Source/Scene/GoogleEarthEnterpriseMapsProvider.js
@@ -105,16 +105,34 @@ function GoogleEarthEnterpriseMapsProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -123,7 +141,7 @@ function GoogleEarthEnterpriseMapsProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -131,7 +149,7 @@ function GoogleEarthEnterpriseMapsProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -140,7 +158,7 @@ function GoogleEarthEnterpriseMapsProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -148,7 +166,7 @@ function GoogleEarthEnterpriseMapsProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default 1.9
    */
   this.defaultGamma = 1.9;
@@ -425,7 +443,7 @@ Object.defineProperties(GoogleEarthEnterpriseMapsProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link GoogleEarthEnterpriseMapsProvider#ready} returns true.
    * @memberof GoogleEarthEnterpriseMapsProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/GridImageryProvider.js b/Source/Scene/GridImageryProvider.js
index 875bc143f678..1e780c0e6e15 100644
--- a/Source/Scene/GridImageryProvider.js
+++ b/Source/Scene/GridImageryProvider.js
@@ -44,16 +44,34 @@ function GridImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -62,7 +80,7 @@ function GridImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -70,7 +88,7 @@ function GridImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -79,7 +97,7 @@ function GridImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -87,7 +105,7 @@ function GridImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -177,7 +195,7 @@ Object.defineProperties(GridImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link GridImageryProvider#ready} returns true.
    * @memberof GridImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/ImageryProvider.js b/Source/Scene/ImageryProvider.js
index 616bcbcbe8f9..77c53f6975a9 100644
--- a/Source/Scene/ImageryProvider.js
+++ b/Source/Scene/ImageryProvider.js
@@ -36,7 +36,7 @@ function ImageryProvider() {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
@@ -45,7 +45,7 @@ function ImageryProvider() {
    * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultNightAlpha = undefined;
@@ -54,7 +54,7 @@ function ImageryProvider() {
    * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultDayAlpha = undefined;
@@ -63,7 +63,7 @@ function ImageryProvider() {
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -72,7 +72,7 @@ function ImageryProvider() {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -80,7 +80,7 @@ function ImageryProvider() {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -89,7 +89,7 @@ function ImageryProvider() {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -97,7 +97,7 @@ function ImageryProvider() {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -179,7 +179,7 @@ Object.defineProperties(ImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link ImageryProvider#ready} returns true.
    * @memberof ImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/IonImageryProvider.js b/Source/Scene/IonImageryProvider.js
index bea2963e3e50..d13495957e94 100644
--- a/Source/Scene/IonImageryProvider.js
+++ b/Source/Scene/IonImageryProvider.js
@@ -69,16 +69,34 @@ function IonImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -87,7 +105,7 @@ function IonImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -95,7 +113,7 @@ function IonImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -104,7 +122,7 @@ function IonImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -112,7 +130,7 @@ function IonImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -289,7 +307,7 @@ Object.defineProperties(IonImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link IonImageryProvider#ready} returns true.
    * @memberof IonImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/MapboxImageryProvider.js b/Source/Scene/MapboxImageryProvider.js
index 0ffa60334167..79caf55821b6 100644
--- a/Source/Scene/MapboxImageryProvider.js
+++ b/Source/Scene/MapboxImageryProvider.js
@@ -60,16 +60,34 @@ function MapboxImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -78,7 +96,7 @@ function MapboxImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -86,7 +104,7 @@ function MapboxImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -95,7 +113,7 @@ function MapboxImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -103,7 +121,7 @@ function MapboxImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -253,7 +271,7 @@ Object.defineProperties(MapboxImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link MapboxImageryProvider#ready} returns true.
    * @memberof MapboxImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/MapboxStyleImageryProvider.js b/Source/Scene/MapboxStyleImageryProvider.js
index c1a063fe7c19..6c51a414b32f 100644
--- a/Source/Scene/MapboxStyleImageryProvider.js
+++ b/Source/Scene/MapboxStyleImageryProvider.js
@@ -62,16 +62,34 @@ function MapboxStyleImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -80,7 +98,7 @@ function MapboxStyleImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -88,7 +106,7 @@ function MapboxStyleImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -97,7 +115,7 @@ function MapboxStyleImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -105,7 +123,7 @@ function MapboxStyleImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -265,7 +283,7 @@ Object.defineProperties(MapboxStyleImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link MapboxStyleImageryProvider#ready} returns true.
    * @memberof MapboxStyleImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/SingleTileImageryProvider.js b/Source/Scene/SingleTileImageryProvider.js
index 070344f0452e..f78fe92e4649 100644
--- a/Source/Scene/SingleTileImageryProvider.js
+++ b/Source/Scene/SingleTileImageryProvider.js
@@ -52,16 +52,34 @@ function SingleTileImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -70,7 +88,7 @@ function SingleTileImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -78,7 +96,7 @@ function SingleTileImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -87,7 +105,7 @@ function SingleTileImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -95,7 +113,7 @@ function SingleTileImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -249,7 +267,7 @@ Object.defineProperties(SingleTileImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link SingleTileImageryProvider#ready} returns true.
    * @memberof SingleTileImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/TileCoordinatesImageryProvider.js b/Source/Scene/TileCoordinatesImageryProvider.js
index 6f5c6f66c320..7194766bcefd 100644
--- a/Source/Scene/TileCoordinatesImageryProvider.js
+++ b/Source/Scene/TileCoordinatesImageryProvider.js
@@ -27,7 +27,7 @@ import when from "../ThirdParty/when.js";
  * @alias TileCoordinatesImageryProvider
  * @constructor
  *
- * @param {TileCoordinatesImageryProvider.ConstructorOptions} options Object describing initialization options
+ * @param {TileCoordinatesImageryProvider.ConstructorOptions} [options] Object describing initialization options
  */
 function TileCoordinatesImageryProvider(options) {
   options = defaultValue(options, defaultValue.EMPTY_OBJECT);
@@ -45,16 +45,34 @@ function TileCoordinatesImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -63,7 +81,7 @@ function TileCoordinatesImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -71,7 +89,7 @@ function TileCoordinatesImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -80,7 +98,7 @@ function TileCoordinatesImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -88,7 +106,7 @@ function TileCoordinatesImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -153,7 +171,7 @@ Object.defineProperties(TileCoordinatesImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link TileCoordinatesImageryProvider#ready} returns true.
    * @memberof TileCoordinatesImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/UrlTemplateImageryProvider.js b/Source/Scene/UrlTemplateImageryProvider.js
index 11ad3d14f5f6..3a8482c1f39a 100644
--- a/Source/Scene/UrlTemplateImageryProvider.js
+++ b/Source/Scene/UrlTemplateImageryProvider.js
@@ -220,16 +220,34 @@ function UrlTemplateImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -238,7 +256,7 @@ function UrlTemplateImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -246,7 +264,7 @@ function UrlTemplateImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -255,7 +273,7 @@ function UrlTemplateImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -263,7 +281,7 @@ function UrlTemplateImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -439,7 +457,7 @@ Object.defineProperties(UrlTemplateImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested, or undefined if there is no limit.
    * This function should not be called before {@link UrlTemplateImageryProvider#ready} returns true.
    * @memberof UrlTemplateImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    * @default undefined
    */
diff --git a/Source/Scene/WebMapServiceImageryProvider.js b/Source/Scene/WebMapServiceImageryProvider.js
index 617aa081fcd8..c529269da2a5 100644
--- a/Source/Scene/WebMapServiceImageryProvider.js
+++ b/Source/Scene/WebMapServiceImageryProvider.js
@@ -98,16 +98,34 @@ function WebMapServiceImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -116,7 +134,7 @@ function WebMapServiceImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -124,7 +142,7 @@ function WebMapServiceImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -133,7 +151,7 @@ function WebMapServiceImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -141,7 +159,7 @@ function WebMapServiceImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -368,7 +386,7 @@ Object.defineProperties(WebMapServiceImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link WebMapServiceImageryProvider#ready} returns true.
    * @memberof WebMapServiceImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Scene/WebMapTileServiceImageryProvider.js b/Source/Scene/WebMapTileServiceImageryProvider.js
index 3f95803b98cb..2b3c14755ca6 100644
--- a/Source/Scene/WebMapTileServiceImageryProvider.js
+++ b/Source/Scene/WebMapTileServiceImageryProvider.js
@@ -141,16 +141,34 @@ function WebMapTileServiceImageryProvider(options) {
    * The default alpha blending value of this provider, with 0.0 representing fully transparent and
    * 1.0 representing fully opaque.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultAlpha = undefined;
 
+  /**
+   * The default alpha blending value on the night side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultNightAlpha = undefined;
+
+  /**
+   * The default alpha blending value on the day side of the globe of this provider, with 0.0 representing fully transparent and
+   * 1.0 representing fully opaque.
+   *
+   * @type {Number|undefined}
+   * @default undefined
+   */
+  this.defaultDayAlpha = undefined;
+
   /**
    * The default brightness of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0
    * makes the imagery darker while greater than 1.0 makes it brighter.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultBrightness = undefined;
@@ -159,7 +177,7 @@ function WebMapTileServiceImageryProvider(options) {
    * The default contrast of this provider.  1.0 uses the unmodified imagery color.  Less than 1.0 reduces
    * the contrast while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultContrast = undefined;
@@ -167,7 +185,7 @@ function WebMapTileServiceImageryProvider(options) {
   /**
    * The default hue of this provider in radians. 0.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultHue = undefined;
@@ -176,7 +194,7 @@ function WebMapTileServiceImageryProvider(options) {
    * The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the
    * saturation while greater than 1.0 increases it.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultSaturation = undefined;
@@ -184,7 +202,7 @@ function WebMapTileServiceImageryProvider(options) {
   /**
    * The default gamma correction to apply to this provider.  1.0 uses the unmodified imagery color.
    *
-   * @type {Number}
+   * @type {Number|undefined}
    * @default undefined
    */
   this.defaultGamma = undefined;
@@ -414,7 +432,7 @@ Object.defineProperties(WebMapTileServiceImageryProvider.prototype, {
    * Gets the maximum level-of-detail that can be requested.  This function should
    * not be called before {@link WebMapTileServiceImageryProvider#ready} returns true.
    * @memberof WebMapTileServiceImageryProvider.prototype
-   * @type {Number}
+   * @type {Number|undefined}
    * @readonly
    */
   maximumLevel: {
diff --git a/Source/Widgets/Viewer/Viewer.js b/Source/Widgets/Viewer/Viewer.js
index c9d7b4e3c4af..fc205ed446f2 100644
--- a/Source/Widgets/Viewer/Viewer.js
+++ b/Source/Widgets/Viewer/Viewer.js
@@ -269,7 +269,7 @@ function enableVRUI(viewer, enabled) {
  * @constructor
  *
  * @param {Element|String} container The DOM element or ID that will contain the widget.
- * @param {Viewer.ConstructorOptions} options Object describing initialization options
+ * @param {Viewer.ConstructorOptions} [options] Object describing initialization options
  *
  * @exception {DeveloperError} Element with id "container" does not exist in the document.
  * @exception {DeveloperError} options.selectedImageryProviderViewModel is not available when not using the BaseLayerPicker widget, specify options.imageryProvider instead.
diff --git a/Specs/TypeScript/index.ts b/Specs/TypeScript/index.ts
new file mode 100644
index 000000000000..4e07cba7180e
--- /dev/null
+++ b/Specs/TypeScript/index.ts
@@ -0,0 +1,160 @@
+import {
+  ArcGisMapServerImageryProvider,
+  BingMapsImageryProvider,
+  ImageryProvider,
+  WebMapServiceImageryProvider,
+  OpenStreetMapImageryProvider,
+  TileMapServiceImageryProvider,
+  GoogleEarthEnterpriseImageryProvider,
+  GoogleEarthEnterpriseMapsProvider,
+  GridImageryProvider,
+  IonImageryProvider,
+  MapboxImageryProvider,
+  MapboxStyleImageryProvider,
+  SingleTileImageryProvider,
+  TileCoordinatesImageryProvider,
+  UrlTemplateImageryProvider,
+  WebMapTileServiceImageryProvider,
+  GoogleEarthEnterpriseMetadata,
+  TerrainProvider,
+  ArcGISTiledElevationTerrainProvider,
+  CesiumTerrainProvider,
+  EllipsoidTerrainProvider,
+  GoogleEarthEnterpriseTerrainProvider,
+  VRTheWorldTerrainProvider,
+  DataSource,
+  CzmlDataSource,
+  GeoJsonDataSource,
+  KmlDataSource,
+  CustomDataSource,
+  Camera,
+  Scene,
+  Property,
+  PropertyBag,
+  ConstantProperty,
+  SampledProperty,
+  PositionProperty,
+  SampledPositionProperty,
+  TimeIntervalCollectionProperty,
+  CompositeProperty,
+  CompositePositionProperty,
+  Cartesian3,
+  ReferenceProperty,
+  MaterialProperty,
+  EntityCollection,
+  CallbackProperty,
+  ConstantPositionProperty,
+  TimeIntervalCollectionPositionProperty,
+  ColorMaterialProperty,
+  CompositeMaterialProperty,
+  GridMaterialProperty,
+  ImageMaterialProperty,
+  PolylineGlowMaterialProperty,
+  PolylineOutlineMaterialProperty,
+  StripeMaterialProperty,
+  CheckerboardMaterialProperty,
+  PolylineDashMaterialProperty,
+  VelocityVectorProperty,
+  VelocityOrientationProperty,
+  PropertyArray,
+  PositionPropertyArray,
+  PolylineArrowMaterialProperty,
+  NodeTransformationProperty,
+} from "cesium";
+
+// Verify ImageryProvider instances conform to the expected interface
+let imageryProvider: ImageryProvider;
+imageryProvider = new WebMapServiceImageryProvider({ url: "", layers: "0" });
+imageryProvider = new BingMapsImageryProvider({ url: "" });
+imageryProvider = new ArcGisMapServerImageryProvider({ url: "" });
+imageryProvider = new BingMapsImageryProvider({ url: "" });
+imageryProvider = new OpenStreetMapImageryProvider({ url: "" });
+imageryProvider = new TileMapServiceImageryProvider({ url: "" });
+imageryProvider = new GridImageryProvider({ url: "" });
+imageryProvider = new IonImageryProvider({ assetId: 2 });
+imageryProvider = new MapboxImageryProvider({ mapId: "" });
+imageryProvider = new MapboxStyleImageryProvider({ styleId: "" });
+imageryProvider = new SingleTileImageryProvider({ url: "" });
+imageryProvider = new TileCoordinatesImageryProvider();
+imageryProvider = new UrlTemplateImageryProvider({ url: "" });
+imageryProvider = new WebMapServiceImageryProvider({ url: "", layers: "" });
+imageryProvider = new GoogleEarthEnterpriseImageryProvider({
+  url: "",
+  metadata: new GoogleEarthEnterpriseMetadata(""),
+});
+imageryProvider = new GoogleEarthEnterpriseMapsProvider({
+  url: "",
+  channel: 1,
+});
+imageryProvider = new WebMapTileServiceImageryProvider({
+  url: "",
+  layer: "",
+  style: "",
+  tileMatrixSetID: "",
+});
+
+// Verify TerrainProvider instances conform to the expected interface
+let terrainProvider: TerrainProvider;
+terrainProvider = new ArcGISTiledElevationTerrainProvider({ url: "" });
+terrainProvider = new CesiumTerrainProvider({ url: "" });
+terrainProvider = new EllipsoidTerrainProvider();
+terrainProvider = new VRTheWorldTerrainProvider({ url: "" });
+terrainProvider = new GoogleEarthEnterpriseTerrainProvider({
+  url: "",
+  metadata: new GoogleEarthEnterpriseMetadata(""),
+});
+
+// Verify DataSource instances conform to the expected interface
+let dataSource: DataSource;
+dataSource = new CzmlDataSource();
+dataSource = new GeoJsonDataSource();
+dataSource = new KmlDataSource({
+  canvas: document.createElement("canvas"),
+  camera: new Camera(new Scene()),
+});
+dataSource = new CustomDataSource();
+
+// Verify Property instances conform to the expected interface
+let property: Property;
+property = new CallbackProperty(() => 0, false);
+property = new ConstantProperty(1);
+property = new TimeIntervalCollectionProperty();
+property = new CompositeProperty();
+property = new SampledProperty(Cartesian3);
+property = new PropertyBag();
+property = new PropertyArray();
+property = new PositionProperty();
+property = new MaterialProperty();
+property = new VelocityVectorProperty();
+property = new VelocityOrientationProperty();
+property = new PositionPropertyArray();
+property = new NodeTransformationProperty();
+property = new ReferenceProperty(new EntityCollection(), "object1", [
+  "billboard",
+  "scale",
+]);
+
+// Verify PositionProperty instances conform to the expected PositionProperty and Property interfaces
+let positionProperty: PositionProperty;
+property = positionProperty = new SampledPositionProperty();
+property = positionProperty = new CompositePositionProperty();
+property = positionProperty = new ConstantPositionProperty();
+property = positionProperty = new TimeIntervalCollectionPositionProperty();
+property = positionProperty = new ReferenceProperty(
+  new EntityCollection(),
+  "object1",
+  ["billboard", "scale"]
+);
+
+// Verify MaterialProperty instances conform to the expected MaterialProperty and Property interfaces
+let materialProperty: MaterialProperty;
+property = materialProperty = new ColorMaterialProperty();
+property = materialProperty = new CompositeMaterialProperty();
+property = materialProperty = new GridMaterialProperty();
+property = materialProperty = new ImageMaterialProperty();
+property = materialProperty = new PolylineGlowMaterialProperty();
+property = materialProperty = new PolylineOutlineMaterialProperty();
+property = materialProperty = new StripeMaterialProperty();
+property = materialProperty = new CheckerboardMaterialProperty();
+property = materialProperty = new PolylineDashMaterialProperty();
+property = materialProperty = new PolylineArrowMaterialProperty();
diff --git a/Specs/TypeScript/tsconfig.json b/Specs/TypeScript/tsconfig.json
new file mode 100644
index 000000000000..3f83cf741b1a
--- /dev/null
+++ b/Specs/TypeScript/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "noEmit": true,
+    "types": [],
+    "strict": true
+  },
+  "include": [
+    "../.."
+  ],
+}
\ No newline at end of file
diff --git a/gulpfile.cjs b/gulpfile.cjs
index 4d8a703910ac..93c5c34b78cf 100644
--- a/gulpfile.cjs
+++ b/gulpfile.cjs
@@ -1594,6 +1594,11 @@ ${source}
     stdio: "inherit",
   });
 
+  // Also compile our smokescreen to make sure interfaces work as expected.
+  child_process.execSync("npx tsc -p Specs/TypeScript/tsconfig.json", {
+    stdio: "inherit",
+  });
+
   // Below is a sanity check to make sure we didn't leave anything out that
   // we don't already know about