When exactly was Jesus born?

The Year

1. The ministry of John started in the 15th year of Tiberius Caesar (Lk 3:1-2), ranging from September 16, 28 AD – September 15, 29 AD (Wikipedia) according to the Gregorian calendar. Shortly after, John baptized Jesus. At that time, Jesus was around 30 years old (Lk 3:21-23). Suppose that around 30 is lower bounded by 28 and upper bounded by 32. Then, Jesus' date of birth is limited to a period of five Gregorian years, ranging from September, 5 BC to September, 1 AD. Note that the Gregorian calendar does not know the year zero. After the year 1 BC comes the year 1 AD.


2. When Jesus was born, the king of Judea Herod was empowered (Mt 2:1-3). When Herod got to hear that another king, Jesus, was born, he got furious and ordered to kill all Jewish babies who were two years old and under (Mt 2:16). Hence, Jesus was maximum two years old and likely older than six months at that time. As Jesus must have been born September, 5 BC or later, he was at least 6 months old in March, 4 BC or later when Herodes was still alive.


3. According to Flavius Josephus, a reputed Romano-Jewish historian of the first-century (Wikipedia), Herod died between a lunar eclipse (Antiquities of the Jews XVII:6:4) and the following Passover (Antiquities of the Jews XVII:8:1). In the night of the moon eclipse Herod burnt some Matthias who raised a sedition against the ex-high priest Matthias ben Theophilus.
   To compute the death of Herod, we just need to study the relevant moon eclipses. The following table shows all partial and total moon eclipses in the period of interest (NASA), the date of the first astronomical new moon after the vernal spring equinox (Astro Pixels) and the following Passover. Passover starts on 14 Nissan (Ex 12:18). Nissan is the first month in the Jewish calendar. During the Roman period Nissan started on the first visible crescent after the spring equinox. The day of Passover corresponds to the astronomical New Moon + 14 days + 24 hours for the crescent be visible. All dates are based on the Gregorian calendar. All timings are in Local Time i.e., Greenwich Time + 2 hrs.
   
   

   Date of Eclipse	Time of Greatest Eclipse	Eclipse Type	Phase Duration	Astronomical New Moon Conjunction	14th day of Nisan (Passover)
   (Gregorian calendar)	(Local TD)		(minutes)	(On date, or first after vernal Equinox)	(Beginning at sunset the evening before...)
   4 BC, Mar. 11	5:37 am	P	138	4 BC, Mar. 25, 6 am	4 BC, Apr. 9
   4 BC, Sep. 3	4:03 pm*	P	168	3 BC, Apr. 13, 6 am	3 BC, Mar. 30
   2 BC, Jan. 18	4:48 pm*	P	164	2 BC, Apr. 2, 11 pm**	2 BC, Apr. 18
   2 BC, Jul. 15	10:09 am*	P	190	1 BC, Mar. 22, 2 pm	1 BC, Apr. 6
   1 BC, Jan. 8	4:04 am	T	99	1 BC, Mar. 22, 2 pm	1 BC, Apr. 6
   1 BC, Jul. 3	1:33 pm*	T	94	1 AD, Apr. 10, 11 am	1 AD, Apr. 25
   1 BC, Dec. 27	7:27 pm	P	151.2	1 AD, Apr. 10, 11 am	1 AD, Apr. 25
   1 AD, Jun. 22	2:08 pm*	P	57.9	2 AD, Mar. 30, 4 pm	2 AD, Apr. 14
   2 AD, May 13	9:24 am*	P	63.5	3 AD, Apr. 18, 10 am	3 AD, May 2

   *not visible from Israel.
   **too late in the day for crescent to be seen the next evening.
   
   The table leaves three options for the said moon eclipse: March 11, 4 BC (partial); January 8, 1 BC (total); and Dec. 27, 1 BC (partial). All the other moon eclipses during that period were invisible in Israel. The death of Herod has generally been associated with the partial eclipse on March 11, 4 BC. However, there is a long list of arguments that speak against this date:
   
   1. From Flavius Josephus we know that the battle of Actium was in the seventh year of the reign of Herod (Antiquities of the Jews XV:5:2). The battle of Actium is well documented in the history. It occurred on August 31, 31 BC. Hence, Herod started to reign in the year 38/37 BC. Herod reigned 37 years (Antiquities of the Jews XVII:8:1). Therefore, Herod must have died some-when in between the second half of 1 BC and the first half of 1 AD, and not in 4 BC. A detailed analysis of the historical events related to the death of Herod can be found in the peer-reviewed article Novum Testamentum 51 (2009), pp. 1–29 by A. E. Steinmann.
   2. March 11, 4 BC was the 14th day of Adar, on which the Hebrews celebrated Purim. It is unlikely, that a former high priest got executed during a Jewish festival.
   3. As Jesus Christ could not be born before the month of September in the year 5 BC, he would have been a few month old baby in the spring of 4 BC. It is unclear why Herod killed much older babies, namely age of two, instead (Mt 2:16).
   4. The time of the greatest (partial) eclipse was shortly before moon-set i.e., sunrise. This kind of eclipse usually goes unnoticed.
   Therefore the two moon eclipses on March 11, 4 BC and on Jan. 8, 1 BC are out of interest. Herod must have died between the partial moon eclipse on Dec. 27, 1 BC and the Passover on April 25, 1 AD. Though that moon eclipse was partial, it was visible to everybody during evening time.
   
   As Herod died in the begin of the year 1 AD, it follows from 1) and 2) that Jesus was born between September, 5 BC and Fall of 2 BC.


4. Tertullian, a profilic early Christian author (Wikipedia), states that Jesus was born in the 41th year of Augustus and the 28th year after the death of Cleopatra (Tertulliani liber Adversus Iudaeos 8:11). In August of the year 43 BC, Octavian alias Augustus marched on Rome and forced the senate to accept him as consul (Roman-Empire.net). As Cleopatra died on August 12, 30 BC (Wikipedia), Jesus' birth range narrows down to one year between August, 3 BC and August, 2 BC.

The Season

1. The scriptures says that Joseph went from Nazareth to Bethlehem prior to the birth of Jesus (Lk 2:4). The distance between Nazareth and Bethlehem is around 170 km. The climate in Bethlehem (CLIMATE-DATA.ORG) indicates that summer-time is too hot, to manage this large distance.


2. When Jesus was born, Shepherds were keeping watch over their flocks at night (Lk 2:8-12). Winter are mild but too wet, to stay outside overnight. Hence, flocks remain out in the field from March/April to October/November, only.


3. The freshly born child slept in a manger, implying that nights were mild (Lk 2:7). As a consequence, Jesus was born either in early fall, 3 BC or in late spring, 2 BC.