diff --git a/moto/rds/models.py b/moto/rds/models.py
--- a/moto/rds/models.py
+++ b/moto/rds/models.py
@@ -54,7 +54,7 @@ def __init__(self, **kwargs):
         self.account_id = kwargs.get("account_id")
         self.region_name = kwargs.get("region")
         self.cluster_create_time = iso_8601_datetime_with_milliseconds(
-            datetime.datetime.now()
+            datetime.datetime.utcnow()
         )
         self.copy_tags_to_snapshot = kwargs.get("copy_tags_to_snapshot")
         if self.copy_tags_to_snapshot is None:
@@ -107,6 +107,9 @@ def __init__(self, **kwargs):
             kwargs.get("enable_cloudwatch_logs_exports") or []
         )
         self.enable_http_endpoint = kwargs.get("enable_http_endpoint")
+        self.earliest_restorable_time = iso_8601_datetime_with_milliseconds(
+            datetime.datetime.utcnow()
+        )
 
     @property
     def db_cluster_arn(self):
@@ -178,6 +181,7 @@ def to_xml(self):
               <DBClusterParameterGroup>{{ cluster.parameter_group }}</DBClusterParameterGroup>
               <DBSubnetGroup>{{ cluster.subnet_group }}</DBSubnetGroup>
               <ClusterCreateTime>{{ cluster.cluster_create_time }}</ClusterCreateTime>
+              <EarliestRestorableTime>{{ cluster.earliest_restorable_time }}</EarliestRestorableTime>
               <Engine>{{ cluster.engine }}</Engine>
               <Status>{{ cluster.status }}</Status>
               <Endpoint>{{ cluster.endpoint }}</Endpoint>

diff --git a/tests/test_rds/test_rds_clusters.py b/tests/test_rds/test_rds_clusters.py
--- a/tests/test_rds/test_rds_clusters.py
+++ b/tests/test_rds/test_rds_clusters.py
@@ -189,6 +189,9 @@ def test_create_db_cluster__verify_default_properties():
     cluster.should.have.key("DomainMemberships").equal([])
     cluster.should.have.key("TagList").equal([])
     cluster.should.have.key("ClusterCreateTime")
+    cluster.should.have.key(
+        "EarliestRestorableTime"
+    ).should.be.greater_than_or_equal_to(cluster["ClusterCreateTime"])
 
 
 @mock_rds

earliestRestorableTime missing from result rds.describe_db_cluster
`rds.describe_db_clusters` is not returning the property `earliestRestorableTime` when the cluster has a snapshot

tests/test_rds/test_rds_clusters.py::test_create_db_cluster__verify_default_properties
tests/test_rds/test_rds_clusters.py::test_start_db_cluster_without_stopping tests/test_rds/test_rds_clusters.py::test_modify_db_cluster_needs_long_master_user_password tests/test_rds/test_rds_clusters.py::test_modify_db_cluster_new_cluster_identifier tests/test_rds/test_rds_clusters.py::test_copy_db_cluster_snapshot_fails_for_unknown_snapshot tests/test_rds/test_rds_clusters.py::test_start_db_cluster_after_stopping tests/test_rds/test_rds_clusters.py::test_create_db_cluster_snapshot_fails_for_unknown_cluster tests/test_rds/test_rds_clusters.py::test_create_db_cluster_needs_long_master_user_password tests/test_rds/test_rds_clusters.py::test_delete_db_cluster tests/test_rds/test_rds_clusters.py::test_delete_db_cluster_that_is_protected tests/test_rds/test_rds_clusters.py::test_create_db_cluster_snapshot_copy_tags tests/test_rds/test_rds_clusters.py::test_copy_db_cluster_snapshot tests/test_rds/test_rds_clusters.py::test_describe_db_cluster_initial tests/test_rds/test_rds_clusters.py::test_stop_db_cluster tests/test_rds/test_rds_clusters.py::test_create_db_cluster_with_enable_http_endpoint_valid tests/test_rds/test_rds_clusters.py::test_delete_db_cluster_do_snapshot tests/test_rds/test_rds_clusters.py::test_add_tags_to_cluster tests/test_rds/test_rds_clusters.py::test_describe_db_cluster_after_creation tests/test_rds/test_rds_clusters.py::test_stop_db_cluster_already_stopped tests/test_rds/test_rds_clusters.py::test_describe_db_cluster_snapshots tests/test_rds/test_rds_clusters.py::test_add_tags_to_cluster_snapshot tests/test_rds/test_rds_clusters.py::test_create_db_cluster_snapshot tests/test_rds/test_rds_clusters.py::test_delete_db_cluster_unknown_cluster tests/test_rds/test_rds_clusters.py::test_restore_db_cluster_from_snapshot_and_override_params tests/test_rds/test_rds_clusters.py::test_copy_db_cluster_snapshot_fails_for_existed_target_snapshot tests/test_rds/test_rds_clusters.py::test_describe_db_cluster_fails_for_non_existent_cluster tests/test_rds/test_rds_clusters.py::test_create_db_cluster_with_database_name tests/test_rds/test_rds_clusters.py::test_delete_db_cluster_snapshot tests/test_rds/test_rds_clusters.py::test_create_db_cluster_additional_parameters tests/test_rds/test_rds_clusters.py::test_create_db_cluster_needs_master_user_password tests/test_rds/test_rds_clusters.py::test_restore_db_cluster_from_snapshot tests/test_rds/test_rds_clusters.py::test_create_db_cluster_needs_master_username tests/test_rds/test_rds_clusters.py::test_start_db_cluster_unknown_cluster tests/test_rds/test_rds_clusters.py::test_stop_db_cluster_unknown_cluster tests/test_rds/test_rds_clusters.py::test_create_db_cluster_with_enable_http_endpoint_invalid