This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, December 2, 2022.
Information updated weekly or as needed.
Times given as local St. Louis time which is Central Standard Time (CST). For definitions of terminology used in the night sky update, click the highlighted text. If relying on times posted in Universal Time (UT), St. louis is -6 hours when CST.
Public Telescope Viewings
As part of the Saint Louis Science Center’s First Fridays, weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions. Telescope viewing begins once it is dark. Regardless of the weather on December 2, join us indoors in our planetarium theater for “The Sky Tonight”. Showtime is at 7 p.m.
*** There will not be a First Friday in January 2023. ***
Observing Highlight of the Week
Mars and the Moon appear close together one or two nights every month. On December 7, 2022, the Moon will occult Mars from roughly 9 to 10 pm if viewing from St. Louis. Image credit: Stephen Rahn.
This week, Mars will reach opposition on December 7, 2022, which is the first of four aphelic oppositions for Mars. Roughly every 15 years, there are seven Martian oppositions. Generally, four of the seven are aphelic and three are perihelic. The difference between them has to do with the distance between Earth and Mars during an opposition. Aphelic are greater distances while perihelic are closer. If the terms sound familiar they should as perihelion is the point in which a Sun orbiting object is at its closest to the Sun, and aphelion is when it is most distant from the Sun. For Earth, perihelion currently occurs early in January and aphelion occurs in early July.
Applying these terms to Mars, if oppositions occur when Mars is near perihelion, Mars and Earth will be a bit closer. If it happens when Mars is near aphelion, Earth and Mars are a little farther apart. This means is the next four oppositions of Mars are not favorable. The next group of Martian perihelic oppositions, starts in 2031. Regardless of aphelic or perihelic oppositions, Mars will still be worth viewing through a telescope this month.
While you are checking out Mars on December 7, 2022, you might see Mars disappear behind the Moon for a brief time. On December 7, 2022, most of North America, Europe, Greenland, Iceland and parts of Africa will see an occultation of Mars. For St. Louis viewers, the occultation occurs between 9:00 and 10:00 p.m. lasting for nearly an hour.
In astronomy, occultations are a type of event called a syzygy. This is when three or more astronomical bodies are aligned. For example, every month, when the Moon exhibits new and full phases, the Sun, Earth and Moon are in syzygy. If this alignment of the Sun, Earth and Moon occur when the Moon is at a crossing node, then an eclipse occurs. Eclipses, transits, conjunctions and oppositions, are various types of syzygies. These types of events helped us understand the solar system and those beyond.
The occultation begins around 9:05 p.m. CST and ends at 9:56 p.m. CST for St. Louis viewers. Keep in mind that calculating precise timings is difficult as there are factors that change day to day. To make sure you do not miss key observing times, make sure to start looking several minutes before posted timings. If you are viewing the occultation from a different location, you can find your local timings by changing the viewing location at in-the-sky.org
If you are interested in observing future occultations, I recommend visiting the International Occultation Timing Association. Lunar occultations are a great place to begin but there are several other types of occultations that are beneficial to observe. If this interests you, visit https://occultations.org/
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sunrise is at 7:01 a.m. on Friday, December 2 and sunset is at 4:40 p.m. providing us with a bit under 10 hours of daylight. Even after sunset, light from the Sun will dimly illuminate our sky for roughly 1 hour and 30 minutes. This period is called twilight, which ends around 6:15 p.m. this week. For those with a sundial, local noon occurs around 11:47 a.m. this week.
| Day | Sunrise | Sunset |
|---|---|---|
| 2022-12-02 | 7:01 a.m. | 4:40 p.m. |
| 2022-12-03 | 7:02 a.m. | 4:39 p.m. |
| 2022-12-04 | 7:02 a.m. | 4:39 p.m. |
| 2022-12-05 | 7:03 a.m. | 4:39 p.m. |
| 2022-12-06 | 7:04 a.m. | 4:39 p.m. |
| 2022-12-07 | 7:05 a.m. | 4:39 p.m. |
| 2022-12-08 | 7:06 a.m. | 4:39 p.m. |
| 2022-12-09 | 7:07 a.m. | 4:39 p.m. |
| 2022-12-10 | 7:08 a.m. | 4:39 p.m. |
Moon
Moonrise for Friday, December 2 was at 1:49 p.m. and moonset occurred at 2:24 a.m. on the following day. Friday, December 2, the Moon will exhibit a waxing gibbous phase with 73% of the lunar disk illuminated. Full moon occurs on December 7, 2022, at 10:08 p.m.
International Space Station (ISS) Observing
There are several visible passes of ISS from St. Louis for the week of December 2. They all occur during evening hours. The best passes for this week are listed below. Use the table below for information about these passes.
Catch ISS from St. Louis starting Friday, December 2
| Date | Starts | Max. altitude | Ends | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time | Alt. | Az. | Time | Alt. | Az. | Time | Alt. | Az. | ||
| 04 Dec | -3.3 | 17:52:42 | 10 | NW | 17:55:54 | 41 | NNE | 17:56:51 | 32 | ENE |
| 05 Dec | -2.3 | 18:41:31 | 10 | WNW | 18:44:36 | 35 | SW | 18:44:42 | 35 | SW |
| 06 Dec | -3.4 | 17:53:21 | 10 | NW | 17:56:40 | 66 | SW | 17:59:59 | 10 | SE |
| 07 Dec | -3.8 | 17:05:22 | 10 | NW | 17:08:42 | 68 | NE | 17:12:00 | 10 | ESE |
| 09 Dec | -2 | 17:06:18 | 10 | WNW | 17:09:25 | 36 | SW | 17:12:31 | 10 | SSE |
Magnitude (Mag): The Measure of brightness for a celestial object. The lower the value is, the brighter the object will be.
Altitude (Alt): The angle of a celestial object measured upwards from the observer’s horizon.
Azimuth (Az): The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.
For information about ISS flyovers and other visible satellites, visit www.heavens-above.com
Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:
The Visible Planets
Looking southeast at 7:00 p.m. on December 3, 2022. Credit: Stellarium, EG
Looking south at 1:00 a.m. on December 4, 2022. Credit: Stellarium, EG.
This week, three naked eye planets are visible. Mars rises in the early evening and is visible most of the night. Jupiter and Saturn rise before sunset and will be visible once it is dark. Both Mercury and Venus will be visible later this month in the west after sunset.
Mars
Mars rises at 5:27 p.m. Start looking for the red planet around 6:30 p.m. as it clears trees and buildings. Mars will reach opposition on December 7, 2022. This is the first of four aphelic oppositions of Mars.
Jupiter
Now past opposition, Jupiter will be visible about 30 minutes after sunset. Jupiter reaches superior conjunction on April 11, 2023. As we progress towards this date, we will see Jupiter slowly wander towards the Sun.
Saturn
Now past opposition, Saturn rises before the Sun sets. You can find this giant world in the south about 45 minutes after sunset. Saturn is still a fine target though telescopes and will be a highlight of the evening sky for the rest of the year.
James S. McDonnell Planetarium
Night Sky Update: December 2 – December 10, 2022