This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, September 8, 2026
Information updated weekly or as needed.
Times given as local St. Louis time this week will be in 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. Times posted in the Night Sky Update are in the 24-hour format.
Join us for our next star party, Friday, October 2, 2026, held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page or visit https://www.slsc.org/explore/mcdonnell-planetarium/public-telescope-viewings/
Observing Highlight
This week the Moon transitions from a waning crescent to a waxing crescent phase. In the process, it passes by Jupiter and Venus. Uranus also begins retrograde motion this week indicating we are nearing opposition with the ice giant.
This week starts with the Moon having just past the planet Jupiter. Tomorrow morning, you will find the Moon about 10° east of Jupiter. The pair will make for a nice naked eye target for those awake around 05:30. The moon will exhibit about 3.4% disk illumination so it will be a very thin waning crescent. If you have binoculars take a look at both objects before sunrise.
If you can find the Moon on September 9, 2026, a prominent dark circle will appear near the terminator. This is a crater called Grimaldi. This crater is a large impact basin that stands out due to the dark flood basalt that fills the basin. Grimaldi formed sometime during the pre-Nectarian period of the Moon making between 3.922 and 4.533 billion years old. Due to its old age both its inner and outer rims are highly eroded.
Looking at Jupiter the same night will reveal all four Galilean moons through binoculars. Europa will be found just east of Jupiter, while Io, Callisto and Ganymede will extend west of Jupiter in that order.
A few days later on September 13 and 14, the Moon and Venus will be found low to the southwest after sunset. Their low altitude will make them tough to find but if you can find a clear view to the southwest you should be able to find them. Through binoculars you will see both objects exhibiting a crescent phase. The Moon will be roughly 9.3% illuminated while Venus will be 29.5% illuminated on the 13th. The following day they will exhibit crescents that are 16 % 28.7% illuminated.
A little more challenging this week, you can watch Uranus start retrograde motion. If watched long enough, an observer will see planets shift amongst the background stars. This is how we originally new planets were different. Planets orbit the Sun in a counterclockwise direction if viewed from above the plane of the solar system. This means their prograde or forward motion carries them eastward amongst the stars. When they start retrograde motion, they appear to shift westward amongst the stars. This occurs because we are seeing the planets from changing angles.
The best way to visualize this is to look at your thumb against a distant tree line. Look at it with one eye open and blink back and forth which eye is open. When you do this, you will notice a parallax shift as your thumb appears to move side to side. This happens because your eyes are seeing your thumb from different angles.
Superior planets like Uranus will appear to do a zigzag or a loop-de-loop pattern amongst the background stars. This happens as Earth catches up to and then passes by a planet. This happens because we orbit the Sun faster than the superior planets. With the exception of Mars, we pass by the superior planets once a year. Mars takes about 26 months to cycle through this behavior.
For the next several years, Uranus will be easy to find thanks to its current location in the constellation Taurus. Because Uranus takes 84 years to orbit the Sun, it moves very slowly amongst the background stars. This year you can find Uranus in between the bright open star clusters known as the Pleiades and Hyades.
You will need binoculars to find the planet as it sits at 5.7 magnitude. That is technically within naked eye visibility, but if you don’t know the precise star field Uranus is found in or if you are observing under any light pollution, you will need binoculars.
Start by locating the Pleiades and Hyades star clusters in Taurus. The Hyades will have a V-shape, and the Pleiades will look like a small spoon. Next look for a small rhombus shape of stars above the Hyades. Uranus is found just above this shape. The stars in the rhombus shape are 50, 53, 51 and 56 Tau.
T CrB Nova Update 9/8/2026
If you are still interested in seeing the recurrent nova T Coronae Borealis, there is still hope. The nova has not yet occurred meaning we are in a waiting game. If you are still interested, the part of the sky the nova will appear in is found in the west by the time it is dark. The star system T Coronae Borealis is found in the constellation Corona Borealis which looks like a small U-shape of stars next to the constellation Boötes. By 10 pm the location of T CrB will be overhead. If you cannot observe the sky directly, you can track the behavior of T CrB by checking current magnitude estimates posted at AAVSO here or by visiting spaceweather.com. Current magnitude estimates of the system show it at 10th magnitude.
The Sun and Moon
Sun
Sunrise on Tuesday, September 8 is at 6:36 and sunset is at 19:20 providing 12.3 and 12.73 hours of daylight. 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 20:51 this week. For those with a sundial, local noon occurs around 12:59 on September 8, 2026.
| Day | Sunrise (CDT) | Sunset (CDT) |
| 8-Sep | 6:36 | 19:20 |
| 9-Sep | 6:37 | 19:18 |
| 10-Sep | 6:38 | 19:17 |
| 11-Sep | 6:39 | 19:15 |
| 12-Sep | 6:40 | 19:13 |
| 13-Sep | 6:41 | 19:12 |
| 14-Sep | 6:41 | 19:10 |
| 15-Sep | 6:42 | 19:09 |
| 16-Sep | 6:43 | 19:07 |
| 17-Sep | 6:44 | 19:06 |
| 18-Sep | 6:45 | 19:04 |
Moon
Moonrise for Tuesday, September 8, was at 03:35 and moonset occurs at 18:06. On September 8, 2026, the Moon will exhibit a waning crescent phase with 6% disk illumination. By September 18, 2026, the Moon will exhibit a First quarter phase with 50% disk illumination. New moon occurs on September 10, 2026, at 22:27. First quarter moon occurs on September 18, 2026, at 15:44.
International Space Station (ISS) Observing
Visible passes of ISS from St. Louis for the week of September 8 occur during evening hours. The best of these occur on September 9, 10 and 13. You can find information about these and other satellite passes at https://heavens-above.com. If you are not viewing from the St. Louis area, make sure to change your viewing location for your local times.
Visible Planets
View looking east on September 8, 2026, at 22:30. Image created using Stellarium
View looking east on September 9, 2026, at 05:15. Image created using Stellarium
Four naked eye planets will be visible this week. Venus is found in the west after sunset. Saturn is visible in the southeast around 10:30 pm. Mars and Jupiter are visible in east before sunrise.
Venus
Venus is visible in the west after sunset setting by 20:39. Venus will already be difficult to find for some as trees to the west are likely to block your view. Venus reaches its brightest on September 22, 2026, and inferior conjunction on October 23, 2026.
Mars
Mars rises around 01:49 this week clearing the 15° mark by 03:15. This apparition of Mars is not the best as it is an aphelic apparition. ALPO’s guide for the Mars 2026-2027 aphelic apparition shows October 14, 2026, as the beginning of the apparition for those using telescopes between 4 and 8 inches. This is the time frame in which most observers can start seeing the surface of Mars through their telescope. Mars reaches opposition on February 19, 2027.
Jupiter rises this week around 04:00. You will need to wait for the giant world to clear trees, but it should be easy to see in the east by 05:30.
Saturn
Saturn can be found rising in the east around 20:32. Saturn will continue to rise earlier each week until it reaches opposition on October 4, 2026.
Our next Star Party will be held on Friday, October 2, 2026 from 6:30 pm to 9:30 pm.
On the first Friday of each month, the St. Louis Astronomical Society and the Saint Louis 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.
The St. Louis Astronomical Society helps host the monthly Star Parties at the Saint Louis Science Center. In addition to our nighttime viewings, they also help facilitate our daytime event called Solar Sundays. These daytime viewing sessions occur on the 3rd Sunday each month. Visit SLAS’s website linked above to learn about other telescope events SLAS hosts around the St. Louis area.
James S. McDonnell Planetarium
Night Sky Update for September 8, 2026
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