Observe the sky: December 2024

New year, new life. Usually with the arrival of a new year we always make good resolutions, drastic changes that we left behind back in February/March, etc. But, what is really a new year? It is nothing more than an arbitrary date, based on an arbitrary position of the Earth in its orbit around the Sun, and therefore, January is as good a date to start as December, don’t you think?

With this article we begin a new part of “Observe the sky from the Science Faculty”, a project that is possible thanks to the Faculty of Science and the Galactic Astrophysics Group of the Department of Theoretical Physics and Cosmos of our University and whose aim is to bring the firmament that surrounds us to anyone interested. Thus, after some failed observations (October and November), “The sky of the month” is born, a series of monthly articles in which we will give you clues about where to look to enjoy the spectacle that a night sky can offer us. The goal is to bring the sky of Granada to your homes, beyond our monthly activities. And to begin with, here are the main astronomical events for the month of December:

Day	Time	Event
1	07:25	New moon
2	02:31	Moon in conjunction with Mercury, just 4.91° to the South
4	17:16	Saturn in quadrature
5	00:35	Moon conjunct Venus, only 2.19° to the South
6	03:12	Mercury in inferior conjunction
7	22:00	Jupiter in opposition
8	09:45	Moon in conjunction with Saturn, just 0.27° to the North
8	16:28	Moon in first quarter
12	14:41	Moon at perigee, minimum distance from Earth this month (365378 km)
14	19:45	Moon in conjunction with Jupiter, 5.42° to the North
15	00:00	Geminids 2024. During the night of December 14-15
15	10:04	Full Moon
18	10:16	Moon in conjunction with Mars, only 0.87° to the North
18	15:11	Neptune in quadrature
21	10:07	Winter Solstice
22	23:21	Moon in third quarter
24	08:37	Moon at apogee, maximum distance from Earth (404459 km)
25	03:54	Mercury at its maximum west elongation (22.05°)
29	04:04	crescent Moon in conjunction with Mercury, only 6.34° to the South
30	23:29	New Moon

Table 1: Main astronomical events of the month of December. Local time.

There are a couple of things that can catch our attention. On the one hand, on the night of December 14-15 we could enjoy one of the most spectacular meteor showers of the year, the Geminids. Unfortunately, the Moon will be in its full phase on the 15th at 10:04 am, almost coinciding with the maximum expected activity. Its light (sunlight reflected on its surface) will make the observation of this meteor shower very difficult, allowing us to observe only the brightest meteors.

Another peculiarity of this month, which is nothing more than a coincidence of no great interest, is that in December the Moon will be in its new phase twice, once on the 1st, and again, after a lunar cycle of nearly 29 days, on December 30, almost with the grapes ready to welcome the new year. Some people call this second Moon the “Black Moon”, but I repeat, it is more a curiosity and coincidence than anything else. For more information about the Sun and the Moon (phases, when to observe, etc), here you have information about these two bodies in the month of December. What a low altitude has the Sun these days! Don’t worry, during the winter and spring the Sun will be gaining height.

Sun during December 2024. — **Figura 1:** Variation of the Sun's position during the month of December. Left: Maximum daily elevation of the Sun during the month. Right: Position in the sky if observed every day at the same time (12.00 UT). In orange the positions of the Sun throughout December; in yellow, throughout the year (analemma).

Moon during December 2024. — **Figura 2:** Observability and illumination of the Moon during the month of December 2024. In red the time zone (universal time, UT; local time = UT + 1) during which you will be able to observe the Moon. The vertical white lines indicate the time of the Moon's passage through the local meridian.

Moon during December 2024 (II). — **Figura 3:** Phases and Moon orbit during December 2024.

But as not everything is the Sun and the Moon (although they are the brightest objects in the sky), here you have information about when and how to observe the planets of the Solar System, some of which I hope we can catch in this month’s observation. As you will see, this December is a good month for planetary observation. All planets will be observable at the beginning of the night and for a good number of hours (with the exception of Mars which will only be observable at the beginning of the night at the end of the month, well, and Mercury, which we already know is very elusive).

Planets observability towards the beginning of december 2024 — **Figura 4:** Observability of the different planets of the Solar System from Granada in December 2024. In red, the time zone (universal time) during which you will be able to observe the different planets. The vertical white lines indicate the time of the passage of the various planets through the local meridian.

Planets observability towards the middle of december 2024 — **Figura 4:** Observability of the different planets of the Solar System from Granada in December 2024. In red, the time zone (universal time) during which you will be able to observe the different planets. The vertical white lines indicate the time of the passage of the various planets through the local meridian.

Planetary situation for the month of December 2024 in Granada. — **Figura 5:** Representation of the sky that will be observable at the end, beginning and middle of a typical December night from Granada (December 15th is chosen as representative). The positions of the planets as well as their motion relative to the fixed stellar background are indicated. For the planets with less apparent motion (Jupiter, Saturn, Uranus and Neptune) a zoom is included for tracking with telescopes.

Last but not least, we leave you with a stellar map to facilitate orientation in the night sky and make it easier to locate constellations on a clear night. Some deep sky objects easily observable with small binoculars from almost any sky are included. During this month’s observation we will try to locate some of them despite observing from the center of Granada. Let’s see if we are lucky.

The sky over Granada during the month of December 2024. — **Figura 6:** Representation of the sky that will be observable on a typical December night from Granada. The ecliptic is indicated (dashed line) as well as the main deep sky objects.

With this we say goodbye for now. We hope you liked this first post, that you find it useful, and that it is only one of many better ones to come. We do not leave you without reminding you to subscribe to our Telegram group where you can be updated on activities, ask questions and receive timely notifications. Here you have the link! We hope to see you soon in our activities.

Clear Skies, happy solstice, happy end of the year, happy holidays, and happy new year!