Roman denarius depicting Augustus (reigned in 27 BCE – 14 CE). The silver coin was minted around 19- 18 BCE, probably in one of the Spanish mints. On the obverse, we see the princeps with a wreath of oak leaves on the head (so-called corna civica). On the reverse, in turn, there is an embossed inscription DIVVS IVLIVS and a comet with eight rays and a tail of fire.
The coin is propaganda and refers to the divinity of Julius Caesar and the event that was to take place in July 44 BCE – four months after the murder of Caesar – during a great ceremony in memory of Caesar – Ludi Victoriae Caesaris. At that time, an extremely bright object was to appear in the sky that caught the attention of the Romans gathered. Due to the fact that Caesar recognized himself (as a member of the Julius family) as a descendant of the goddess Venus herself, and the Roman Senate officially recognized Caesar as a god, crowds seeing the comet in the sky considered this as confirmation of Caesar’s divinity, and the star itself was to contain the soul of the leader.
As Suetonius later reports:
[…] a comet shone for seven successive days, rising about the eleventh hour, and was believed to be the soul of Caesar.
– Suetonius, Julius Caesar, 88
Obviously, the phenomenon observed by the ancients was a falling comet, which astronomers felt could be the brightest that humans have ever observed. Ancient authors described it as Sidus Iulium (“Julian Star”) or Caesaris astrum (“Star of Julius Caesar”).
In 44 BCE Gaius Octavian – not yet having any real significance on the political scene of Rome – used this event for propaganda purposes. In 42 BCE the Temple of Caesar was founded, which in 29 BCE received a dedication in honour of the event with the comet. A large image of Caesar was placed on the wall of the temple, on whose forehead – according to Ovid (“Metamorphoses”, XV.745-842) – a comet was attached. In this way, Octavian emphasized the symbolism of the event, the divinity of Caesar and emphasized his legitimacy of power as the successor of the beloved leader.