AstroCal – January 2024

Happy New Year! You can begin your observing for the new year in the early morning hours of January 1 – 40 minutes before sunrise -4.0 magnitude Venus will be shining brightly in the SE.

Venus will be at superior conjunction on the far side of the Sun on June 4 so we will see the distance between the planet and the rising sun decrease from 37 degrees to 31 degrees during January. This also means Venus will be getting farther and farther away from the Earth and dropping lower toward the horizon each month. The phase we see will rise from 78 percent lit (spanning 14 arcseconds) to 86 percent during the month, but the increasing distance will see the planetary disk reduced to 12 arcseconds.

Mercury will be visible to the lower left of Venus in the morning twilight. The innermost planet reaches its highest elevation above the horizon on Jan 8 and its greatest elongation 23.5 degrees west of the Sun on Jan 12. Mercury’s magnitude on Jan 1 will be +0.4 and it will increase to -0.3 by the end of the month (remember, the smaller the magnitude number, the brighter the object will appear). Mars will be faint at the beginning of the month and may require binoculars to see to the lower left of Mercury through Jan 26. Thereafter, the Red Planet will appear to the upper right of Mercury which will be dropping lower in the sky each day.

The evening planets will continue to feature Jupiter high in the SE one hour after sunset. It will be in prime viewing position as it crosses toward the SSW during the night. Located in the constellation of Aries, the Ram, Jupiter will shine at mag 2.6 early in the month and -2.4 by Jan 31. Saturn can be seen in Aquarius, the Water Bearer with a magnitude of +0.9 as it sinks from the SW to the WSW horizon. The rings will be seen at 9.1 degrees and reduce to 7.7 degrees from edge on as the month progresses.

Charts to find Uranus and Neptune can be found at abramsplanetarium.org/msta along with information about the occultation of Antares.

Lunar highlights for January will include the Last Quarter Moon on Jan 3 and the occultation of Antares (mentioned above) on Jan 8. The New Moon of the new cycle will take place on Jan 11, with the first very young Crescent Moon visible low in the SW on Jan 12 and 13. The First Quarter can be seen on Jan 17 and the Full Moon will brighten the night skies on Jan 25.

This month’s Historical Astronomy event was detailed for the American Astronomical Society by Cornell University’s Philip Nicholson. Nicholson recalls it was in early January 1610 that Galileo looked heavenward with his newly improved telescope. As he focused on the planet Jupiter, he found that there seemed to be three bright stars (soon to be joined by a fourth) that accompanied the planet in its daily motions. It did not take many days of observation for Galileo to realize these ‘stars’ were orbiting Jupiter much like our Moon orbits the Earth. Coupled with the phases of Venus he saw near the end of 1610, he had gathered strong support for the Copernican model of the Solar System. Unfortunately for Galileo, church doctrine of the day favored the ‘Earth-centered’ universe and his support of the ‘Sun-centered’ model branded him as a heretic. When he refused to alter his views (although he did print a tepid retraction that more or less ended with a ‘but I am not wrong’), he was placed under house arrest for the remainder of his life.

Even though he was correct in his embrace of the Copernican theory, it would take more than 300 years for Galileo’s ‘crime’ to be stricken from the books. Had he not had friends in high places, he probably would have suffered the same fate as his contemporary, astronomer Giovani Bruno, who was burned at the stake for making similar heretical statements. There is an excellent book out there (Galileo’s Daughter by Dava Sobel – 1999) based on surviving letters of his daughter (the nun Suor Maria Celeste) that explores their relationship. The ‘Galilean Moons’ are easily seen with binoculars and the continued presence of Jupiter in our winter skies gives everyone a great opportunity to explore them just as Galileo did 414 years ago this month.

Compiled by Ken Raisanen of WOAS-FM – information provided by Abrams Planetarium Sky Calendar, Michigan State University. More information and subscription information can be found on their website at http://abramsplanetarium.org/skycalendar/ or on X (formerly Twitter) at http://twitter.com/AbramsSkyNotes. Yearly subscriptions cost $12 and can be started anytime.