This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, October 21, 2023.
Information updated weekly or as needed.
Times given as local St. Louis time which is Central Daylight Time (CDT). 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 -5 hours when CDT.
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 November 3 , join us indoors in our planetarium theater for “The Sky Tonight”. Showtime is at 7 p.m. There is no First Friday event in July.
Observing Highlight of the Week
Orionid meteor seen from Death Valley National Park. Image credit: Brocken Inaglory.
Every year from September 26 to November 22, Earth encounters debris left over from comet 1P/ Halley. As Earth approaches the debris left behind by the comet the annual meteor shower called the Orionids begins. During this time, it is possible to see debris from comet 1P/Halley enter Earth’s atmosphere producing bright meteors. For most of this period, activity is low but as we get near the core of the debris stream meteor activity will increase. The Orionids are a moderate meteor shower producing 15 to 20 meteors per hour during peak activity if viewed from a dark location.
Viewing meteor showers is a simple and enjoyable experience provided you keep a few things in mind. First and foremost, the darker the sky the more meteors you can see. As you read articles about meteors showers, the posted rates of activity are always assumed you are viewing from a dark location. If you view from a site in light pollution, the rate of visible meteors will be dramatically reduced. From St. Louis, I would expect the Orionid peak rate of 15 to 20 meteors per hour to be lower or sporadic under light polluted skies.
Another form of light pollution some might not think about is the Moon. As we approach full moon, the Moon appears brighter due to the opposition effect. This results from the angle of sunlight striking the Moon’s surface. When the Moon is at its full phase, it is near the anti-solar point in the sky. What results from this is shadows cast by surface features are pointed away from the viewer. This results in more bright areas than dark and the Moon looks brighter. The good news for the Orionids is the Moon will be at first quarter phase during peak activity. This means the Moon will set before the Orionid radiant is ideally placed in our sky.
Another key factor in seeing meteors is the length of time you observe. If you step outside for a few minutes, chances are you will not see any. Posted visibility rates are per hour so the longer you sit outside the more meteors you will see. If you don’t have hours to sit outside, whatever time you have is worth doing but the more time the better. I like to use a reclining lawn or patio chair that allows me to be nearly flat. Once a meteor shower radiant is high in the sky, a reclining chair will give you the best view without torqueing your neck.
When viewing a meteor shower you will want to know where its radiant is located. This will give you an idea of where to look. The radiant of a meteor shower is the point in which meteors appear to emanate from. Additionally, the location of a shower’s radiant is how they get their names. For the Orionids, the radiant is located in the constellation Orion about 10° north of the bright star Betelgeuse. When the radiant is low to the horizon you want to look in its direction. However, as it rises high enough in the sky, meteors can be seen moving in all directions traveling away from the radiant. From St. Louis, you can start to see meteors as early as 10:00 p.m. however, your best chance to see meteors comes after 1:00 a.m., once the radiant is over 30° above the horizon.
The Orionids traditionally peak each year around October 21, 2023. This year they are expected to peak on October 22, 2023, around 00:05 UTC, which converts to 7:05 p.m. CDT in St. Louis on October 21, 2023. Peak activity will be occurring as Orion rises in the southeast around 10:00 p.m. Some meteor showers exhibit very brief peak periods. However, the Orionids can have a prolonged period of higher activity centered on the date of maximum activity. The best time to look for Orionids is the night of October 21/22, 2023, but the evenings before and after this date are also decent options.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sun
Sunrise is at 7:16 a.m. on Saturday, October 21 and sunset is at 6:14 p.m. providing us with roughly 11 hours of daylight this week. Even after sunset, light from the Sun will dimly illuminate our sky for about 1 hour and 30 minutes. This period is called twilight, which ends around 7:43 p.m. this week. For those with a sundial, local noon occurs around 12:45 p.m. this week.
| Day | Sunrise | Sunset | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 21-Oct | 7:16 a.m. | 6:14 p.m. | ||||||||||
| 22-Oct | 7:17 a.m. | 6:13 p.m. | ||||||||||
| 23-Oct | 7:18 a.m. | 6:12 p.m. | ||||||||||
| 24-Oct | 7:19 a.m. | 6:10 p.m. | ||||||||||
| 25-Oct | 7:20 a.m. | 6:09 p.m. | ||||||||||
| 26-Oct | 7:21 a.m. | 6:08 p.m. | ||||||||||
| 27-Oct | 7:22 a.m. | 6:07 p.m. | ||||||||||
| 28-Oct | 7:23 a.m. | 6:05 p.m. | ||||||||||
| 29-Oct | 7:24 a.m. | 6:04 p.m. |
Moon
Moonrise for Saturday, October 21 was at 2:23 a.m. and moonset will occur at 11:39 p.m. On Saturday, October 21, the Moon will exhibit a waxing crescent phase with 48% disk illumination.
The Moon starts the week off with a waxing crescent phase. By the end of the week, it will exhibit a waning gibbous phase with roughly 99% disk illumination. As we near the end of the week, the Moon will increase in apparent brightness causing issues for deep sky observation. Full moon occurs on October 28, 2023, at 3:24 p.m. October’s full moon is often called the Full Hunter’s Moon. This will be the 11th of 13 full moons in 2023. For observers across Africa, Asia, Europe, Russia and small parts of the Americas and Australia, a partial lunar eclipse occurs on October 28, 2023. Unfortunately, this eclipse is not visible from St. Louis. You can learn more about this eclipse at https://www.timeanddate.com/eclipse/lunar/2023-october-28
International Space Station (ISS) Observing
There are several visible passes of ISS from St. Louis for the week of October 21. They occur during morning hours. The table below list the best of these passes that will be seen from St. Louis. If you do not live in the area, you can use https://heavens-above.com/ to set your viewing location and get times for where you are.
Catch ISS from St. Louis starting Saturday, October 21, 2023
| Date | Starts | Max. altitude | Ends | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time | Alt. | Az. | Time | Alt. | Az. | Time | Alt. | Az. | ||
| 22 Oct | -2.6 | 6:22:41 | 18 | WNW | 6:24:25 | 28 | NNW | 6:27:23 | 10 | NNE |
| 23 Oct | -2.8 | 5:37:04 | 37 | N | 5:37:04 | 37 | N | 5:39:35 | 10 | NE |
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°.
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 9:00 p.m. on October 21, 2023. Credit: Stellarium, EG
Looking southeast at 5:00 a.m. on October 22, 2023. Credit: Stellarium, EG
This week, three naked eye planets will be visible. Saturn will be found in the southeast once it is dark. Jupiter is easy to find in the east by 9:00 p.m. Venus will be easy to find in the east before sunrise.
Venus
Venus rises this week around 3:30 a.m. It will be easy to spot for most by 5:00 a.m. If you have a clear view of the planet, telescopes will reveal a crescent phase with roughly 45.8% disk illumination. Venus will reach maximum western elongation on October 22, 2023. You can count on seeing Venus in the east before sunrise for several months.
Jupiter
Jupiter rises at 6:54 p.m. About one hour after Jupiter rises, it should be easy to spot for those with clear eastern horizons. Jupiter will rise about 30 minutes earlier each week. The ideal time to start looking for Jupiter will be after 9:00 p.m. Jupiter will reach opposition later this year on November 2, 2023.
Saturn
Start looking for Saturn in the southeast about 30 minutes after sunset. If you have lots of trees or buildings, you may have to wait an hour or so after it rises before it will be visible. Saturn will set by 2:33 a.m.
James S. McDonnell Planetarium
Night Sky Update: October 21-29, 2023