diff --git a/README.md b/README.md
index 88c00ab..cf4a83d 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 astrotime
 =========
 
-NOAA astrological algorithms for sunrise and sunset ported to Go
+NOAA astronomical algorithms for sunrise and sunset ported to Go
 
 
 FUNCTIONS:
diff --git a/astrotime_test.go b/astrotime_test.go
new file mode 100644
index 0000000..765730b
--- /dev/null
+++ b/astrotime_test.go
@@ -0,0 +1,157 @@
+package astrotime
+
+import (
+	"testing"
+	"time"
+)
+
+// Fixed location used for testing.
+const TEST_LAT = 37.3894
+const TEST_LONG = 122.0819
+
+func compareApproxTimes(value, expected time.Time) bool {
+	approx := time.Minute
+
+	return value.After(expected.Add(-1*approx)) && value.Before(expected.Add(approx))
+}
+
+func TestCalcSunrise(t *testing.T) {
+
+	expectedSunrise := time.Date(2014, time.June, 12, 05, 47, 00, 0, time.Local)
+
+	// Test well before sunrise.
+	now := time.Date(2014, time.June, 12, 2, 57, 12, 0, time.Local)
+	sunrise := CalcSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunrise) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test 1ns after sunrise.
+	now = expectedSunrise.Add(time.Nanosecond)
+	sunrise = CalcSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunrise) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test well after sunrise.
+	now = time.Date(2014, time.June, 12, 10, 57, 12, 0, time.Local)
+	sunrise = CalcSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunrise) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test late in day.
+	now = time.Date(2014, time.June, 12, 22, 57, 12, 0, time.Local)
+	sunrise = CalcSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunrise) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+}
+
+func TestNextSunrise(t *testing.T) {
+
+	expectedSunriseToday := time.Date(2014, time.June, 12, 05, 47, 00, 0, time.Local)
+	expectedSunriseTomorrow := time.Date(2014, time.June, 13, 05, 46, 58, 0, time.Local)
+
+	// Test well before sunrise.
+	now := time.Date(2014, time.June, 12, 2, 57, 12, 0, time.Local)
+	sunrise := NextSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunriseToday) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test 1ns before sunrise.
+	now = expectedSunriseToday.Add(-1 * time.Nanosecond)
+	sunrise = NextSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunriseToday) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test 1ns after sunrise.
+	now = expectedSunriseToday.Add(time.Nanosecond)
+	sunrise = NextSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunriseTomorrow) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test well after sunrise.
+	now = time.Date(2014, time.June, 12, 10, 57, 12, 0, time.Local)
+	sunrise = NextSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunriseTomorrow) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+
+	// Test late in day.
+	now = time.Date(2014, time.June, 12, 22, 57, 12, 0, time.Local)
+	sunrise = NextSunrise(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunrise, expectedSunriseTomorrow) {
+		t.Error("Unexpected sunrise result:", sunrise)
+	}
+}
+
+func TestCalcSunset(t *testing.T) {
+
+	expectedSunset := time.Date(2014, time.June, 12, 20, 29, 33, 0, time.Local)
+
+	// Test well before sunset.
+	now := time.Date(2014, time.June, 12, 2, 57, 12, 0, time.Local)
+	sunset := CalcSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunset) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test 1ns after sunset.
+	now = expectedSunset.Add(time.Nanosecond)
+	sunset = CalcSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunset) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test well after sunset.
+	now = time.Date(2014, time.June, 12, 10, 57, 12, 0, time.Local)
+	sunset = CalcSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunset) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test late in day.
+	now = time.Date(2014, time.June, 12, 22, 57, 12, 0, time.Local)
+	sunset = CalcSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunset) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+}
+
+func TestNextSunset(t *testing.T) {
+
+	expectedSunsetToday := time.Date(2014, time.June, 12, 20, 29, 42, 0, time.Local)
+	expectedSunsetTomorrow := time.Date(2014, time.June, 13, 20, 30, 18, 0, time.Local)
+
+	// Test well before sunset.
+	now := time.Date(2014, time.June, 12, 2, 57, 12, 0, time.Local)
+	sunset := NextSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunsetToday) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test 1ns before sunset.
+	now = expectedSunsetToday.Add(-1 * time.Nanosecond)
+	sunset = NextSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunsetToday) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test 1ns after sunset.
+	now = expectedSunsetToday.Add(time.Nanosecond)
+	sunset = NextSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunsetTomorrow) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+
+	// Test well after sunset.
+	now = time.Date(2014, time.June, 12, 22, 57, 12, 0, time.Local)
+	sunset = NextSunset(now, TEST_LAT, TEST_LONG)
+	if !compareApproxTimes(sunset, expectedSunsetTomorrow) {
+		t.Error("Unexpected sunset result:", sunset)
+	}
+}