diff --git a/USERGUIDE.md b/USERGUIDE.md
index c345ab4b..643147c1 100644
--- a/USERGUIDE.md
+++ b/USERGUIDE.md
@@ -117,7 +117,7 @@ Starting from the top, the sidebar shows this information:
 “Random Details” are displayed in four columns. The outer ones show the data while the inner ones are the titles.
 
 - owner: who deployed the first resonator after it has been neutral/unclaimed.
-- since: when was the first resonator deployed after it has been neutral/unclaimed.
+- since: when was the first resonator deployed after it has been neutral/unclaimed. The reasonators decay every 24hrs from capture. Move the cursor over it to show the full date time.
 - range: shows how far links made from this portal can be. Click on the value to zoom out to link range. The red circle shows how far links may reach.
 - energy: shows current and maximum energy if fully charged. The tooltip contains the exact numbers.
 - links: shows incoming and outgoing links. The tooltip explains the icons.
diff --git a/code/portal_detail_display.js b/code/portal_detail_display.js
index ffd653c9..f930d5ca 100644
--- a/code/portal_detail_display.js
+++ b/code/portal_detail_display.js
@@ -26,7 +26,10 @@ window.renderPortalDetails = function(guid) {
     : null;
   var playerText = player ? ['owner', player] : null;
 
-  var time = d.captured ? unixTimeToString(d.captured.capturedTime) : null;
+  var time = d.captured
+    ? '<span title="' + unixTimeToString(d.captured.capturedTime, true) + '">'
+      +  unixTimeToString(d.captured.capturedTime) + '</span>'
+    : null;
   var sinceText  = time ? ['since', time] : null;
 
   var linkedFields = ['fields', d.portalV2.linkedFields.length];