StarWatch: Moravian University Astronomy

DECEMBER 2025

DECEMBER STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

lunar phases

1529 DECEMBER 7, 2025: Geminid Maximum Next Sunday Morning: The Geminids, the most plentiful and reliable meteor shower of the year, reach their broad maximum at 4 a.m. on Sunday, December 14. Under perfect conditions, this shower can produce as many as 150 shooting stars per hour; however, those numbers are drastically reduced to 40 events each hour in the light-drenched suburban areas of the East Coast, including the Lehigh Valley. Reliability over the past several decades has pinpointed peak activity as always occurring between December 13 at 11:00 a.m. and December 14 at 8:00 a.m. This year's 4 a.m. maximum represents the ideal predicted time for making observations since the East Coast will be facing into the Geminid meteoroids. This condition is analogous to the front window of a car or truck plowing through a rainstorm, while the back window remains virtually dry. * Geminids intersect Earth's atmosphere at a speed of 22 miles per second as opposed to the August Perseids which ablate in Earth's lower thermosphere and mesosphere at nearly twice that velocity. Geminids also show a variability in brightness. Shortly after the maximum time more luminous shooting stars are witnessed. With all of these advantages going for the biggest meteor shower of the year, cloudy weather, gusty winds, and wintry temperatures have prevented the Geminids from attaining the same popularity as the August Perseids that can have total hourly rates of 60 meteors from rural locales. * Meteors from an organized shower diverge from a small region of the sky called the radiant. The specks of dislodged cometary dust that become the observed meteors move parallel to each other in an analogous fashion to the sides of a road on a straight section of highway. The thoroughfare diverges from a vanishing point in the distance. In meteor science, this position is known as the radiant. This origin point reaches its highest altitude around 3 a.m., only ten degrees from the zenith, just an hour before the predicted maximum. * Geminids will appear to originate just a few degrees to the northwest of the bright star Castor, the mortal twin of the Gemini brothers. This year, mega bright Jupiter sits just ten degrees to the south of the radiant and will act as an initial focal point to spot the location from where Geminids will be streaming. Go here for a map. * Geminids originate from the debris discarded by the periodic comet-turned-asteroid, 3200 Phaethon, with a 1.4-year orbital cycle around the sun. Comets can suffer numerous fates, such as disintegrating if they come too close to the sun's heat. Also over time, Jupiter and the other gas giants can eject them from the solar system or systematically reduce their elongated orbits until some lose their comet-like identities and become asteroid-behaving objects. * Geminid meteors will be most plentiful during the morning of December 14, but first go outside to find the radiant. Look for Jupiter in the east between 10 p.m. and 1 a.m. It will be the brightest star-like object in the sky. Jupiter's location will be to the right and below Castor and Pollux, the heads of the Gemini twins. The radiant is just to the right of the upper Gemini star, Castor. Position yourself looking at Jupiter to catch the greatest number of Geminid meteors. * Don't forget to check your inventory of heat-retaining clothing and hand warmers as well! I would recommend overdressing, since the cold will most likely be the main culprit that drives you indoors after an hour or two of Geminid watching. * Finally, do not worry about the moon. This year's 27 percent waning crescent in the southeast rises shortly after 2 a.m. and will not affect observations. * Wishing everyone good Geminid hunting under clear skies next Saturday evening into Sunday morning. Ad Astra!

1530

DECEMBER 14, 2025: Who Were the Magi?

In her book, The Star of the Magi: The Mystery that Heralded the Coming of Christ, New Page Books, 2007 (Amazon, $38.00), astronomer and science historian Courtney Roberts ventures into lesser known Eastern concepts long dominated by Western thought and theological conjecture. She places the Christmas Story's mysterious figures—the Magi and the Star they witnessed firmly within the context of Persian history and Zoroastrian astronomy/astrology. * Roberts constructs a compelling argument that the Wise Men were not kings but more likely Zoroastrian priests from the Parthian (Persian) Empire (247 BCE to 224 CE), rivaling Rome for power in the Near East. The territory under the Parthian rule included present-day Iran and Iraq, spanning into the western regions of Afghanistan, Pakistan, and India. The Magi in the Christmas story most likely lived in what is today northern Iran and acted as advisors to the Parthian kings. Still, the history of Zoroastrian priests dates to the much earlier Achaemenid (Persian) Empire. The journey of the Wise Men was precipitated by a specific Zoroastrian prophecy that a star would herald the birth of a messiah. Earlier Judeans also knew about this messianic vision because of their close relationship with the Persians. * Roberts believes that the Judeans rewrote the history of Israel in their own religious traditions after the Babylonians sacked and burned Israel's First Temple and the city of Jerusalem in 587 or 586 BCE. Judah was the home of the followers of King David of David and Goliath fame. Its population included two of the 12 tribes founded by the 12 sons of the Jewish patriarch, Jacob. In comparison, more prosperous Israel contained the remaining ten tribes that followed the teachings of King Solomon (of King Solomon's Mines fame) who constructed the First Temple in Jerusalem during the 10th century BCE. This Judean influence would also come to dominate Israel and inspire Matthew's Gospel to trace Christ's lineage directly back to the House of David. * When the Babylonian upheavals occurred in 597 BCE and also in 587-586 BCE (Chaldean Dynasty under Nebuchadnezzar II), it was Israel that suffered. This allowed Judean influences to infiltrate into Israel. In the former event, the elite of Israel were exiled to Babylon. In the latter turmoil, Jerusalem and the First Temple were destroyed and more Israelis were forced into Chaldean captivity. Members of the ten tribes remained in custody until 539 BCE when the Babylonians were overthrown by the Persians under the leadership of Cyrus the Great. Cyrus allowed the Israeli captives, now infused with new Eastern ideas, safe passage back to their homeland (many did not return), which by that time was under Judean rule and traditions. * It was the Persians, who aligned themselves with the Judeans, helping to construct the Second Temple in Jerusalem (536-516 BCE), not so much from altruism but from the need to use Jerusalem as a strategic staging area for the Persian conquest of Egypt (525 BCE). * It becomes apparent in Courtney Roberts' narrative that by the time of Christ's birth, Judeans and Israelis looked to the East for inspiration and commonality, rather than to the Western ideals of the Greeks and Romans. * But who were the Magi? They were the wise men, the religious priests of the first Achaemenid Empire and the later Parthian Empire, who in addition were administrators, advisors, doctors, astrologers, and astronomers. They believed in the teachings of the prophet, Zoroaster, who most likely lived in the sixth century BCE and was possibly a near contemporary of Cyrus the Great, the liberator of the Israelites from the Babylonians. The evolution of the monotheistic Zoroastrian religious beliefs included God and the Devil, Heaven and Hell, the Last Judgment, the Resurrection of the Dead, Angels and Demons, the Virgin Birth of a Savior, and the Ultimate Battle between Good and Evil (Roberts, p. 67). Sound familiar…? Judaism, Christianity, and Islam have many tenets of Zoroastrianism embedded within their worldviews. * Next week, I will discuss the astronomy behind the Star that heralded the birth of Christ. Ad Astra!

1531 DECEMBER 21, 2025:

1532 DECEMBER 28, 2025: