Time constants

src/constants/Time.ts

@@ -1,6 +1,6 @@
 export module Time {
   /**
-   * Timestamp epoch, January 1, 1970.
+   * Timestamp epoch, January 1, 1970, in Julian Days.
    */
   export const epoch: number = 2440587.5;
 

src/model/JulianDay.ts

@@ -1,11 +1,13 @@
+import { Time } from "../constants/Time";
+
 export module JulianDay {
   /**
    * Julian day from Gregorian date.
    * @param date - Gregorian date to convert to Julian day.
    */
   export const fromDate = (date: Date = new Date()): number => {
     const time = date.getTime();
-    return time / 86400000 - date.getTimezoneOffset() / 1440 + 2440587.5;
+    return time / 86400000 - date.getTimezoneOffset() / 1440 + Time.epoch;
   };
 
   /**
@@ -14,7 +16,7 @@ export module JulianDay {
    */
   export const toDate = (julian: number): Date => {
     let date = new Date();
-    date.setTime((julian - 2440587.5 + date.getTimezoneOffset() / 1440) * 86400000);
+    date.setTime((julian - Time.epoch + date.getTimezoneOffset() / 1440) * 86400000);
     return date;
   };
 }

src/model/Moon.ts

@@ -6,7 +6,7 @@ import { Time } from "../constants/Time";
 
 export module Moon {
   /**
-   * Moon's age, or days since the last new moon.
+   * Moon's age, or Earth days since the last new moon.
    *
    * @param date - Date used for calculation.
    * @returns Age of the moon, normalized within a 29.53059 Earth days calendar.