This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, June 24, 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 August 4 , 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
Models of the Mars Rover Perseverance and Mars Helicopter Ingenuity on Display in the James S. McDonnell Planeterium. These full scale models will be on display until June 24, 2024. Image Credit: EG.
Over the last few months, you may have noticed two bright objects in the west creeping closer together each night. These two objects are the planets Mars and Venus. They will appear at their closest on July 1. After this date, Venus will quickly move away from Mars as it heads towards inferior conjunction later in August.
The observing window for both planets is starting to close. Currently, they set a little after 11:00 p.m. Mars will hang on a little longer than Venus as its superior conjunction does not occur until November 18, 2023. Unfortunately, there are two things making Mars difficult to see. First, Earth is speeding away from Mars. Because we are closer to the Sun, we orbit the Sun at a higher speed. Every 26 months, we catch up to Mars around the time Mars reaches opposition. After this we start to pull away, increasing the distance between the two planets. Mars opposition last occurred on December 7, 2022, so we are roughly 20 months away from the next one in 2025. As we move away from Mars, the planet slowly begins to dim. Even at its faintest, Mars is always visible to the unaided eye, however the second issue we have with Mars right now is making it more difficult to see Mars than it should be.
For several weeks now, the fires in Canada and parts of the US, have been spewing smoke into the atmosphere. As this smoke heads south into the US it impacts air quality, and it limits visibility making fainter objects more difficult to see. Mars will still be easy to spot about an hour after sunset, but it might be challenging to see it in the early hour of twilight.
While Mars will be visible in the west until November, the window to see Venus in the evening is quickly closing. Venus will continue to brighten until July 9, 2023. If you have binoculars at home, you should be able to see the phase of Venus. Each day Venus will appear closer to the Sun until we lose it in the Sun’s glare. Venus reaches inferior conjunction on August 12, 2023. As we approach this date, it will become dangerous to look for Venus due to how close it will appear to the Sun. The best views will continue into July, but keep in mind, Venus will get closer to the Sun each day. It is possible to see Venus in the daytime, but that can be dangerous if you do not know exactly where to look. I do not recommend trying this if you are new to observing.
The Moon will pass by Venus one more time before we lose Venus to the Sun’s glare. This occurs on the nights of July 19 and 20. You will need a clear horizon to see the pair as they will only be about 12° above the horizon when the Sun is setting.
After we lose Venus, those interested in planets will have to shift to late night and early morning session to spot Saturn and Jupiter. Both planets will rise earlier each night as they head towards opposition later this year.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sunrise is at 5:37 a.m. on Friday, June 24 and sunset is at 8:29 p.m. providing us with nearly 15 hours of daylight. Even after sunset, light from the Sun will dimly illuminate our sky for roughly 2 hours. This period is called twilight, which ends around 10:28 p.m. this week. For those with a sundial, local noon occurs around 1:03 p.m. this week.
| Day | Sunrise | Sunset | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 24-Jun | 5:37 a.m. | 8:29 p.m. | ||||||||||
| 25-Jun | 5:37 a.m. | 8:29 p.m. | ||||||||||
| 26-Jun | 5:38 a.m. | 8:29 p.m. | ||||||||||
| 27-Jun | 5:38 a.m. | 8:29 p.m. | ||||||||||
| 28-Jun | 5:39 a.m. | 8:29 p.m. | ||||||||||
| 29-Jun | 5:39 a.m. | 8:29 p.m. | ||||||||||
| 30-Jun | 5:39 a.m. | 8:29 p.m. | ||||||||||
| 1-Jul | 5:40 a.m. | 8:29 p.m. | ||||||||||
| 2-Jul | 5:40 a.m. | 8:29 p.m. |
Moon
Moonrise for Saturday, June 24 is at 11:31 a.m. and moonset occurs at 12:43 a.m. on the following day. On Saturday, June 24, the Moon will exhibit a waxing crescent phase with 38% disk illumination. First quarter moon occurs on June 26, 2023, at 2:50 a.m.
International Space Station (ISS) Observing
There are a few visible passes of ISS from St. Louis for the week of June 16. They occur during morning 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 Saturday, June 24
| Date | Starts | Max. altitude | Ends | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time | Alt. | Az. | Time | Alt. | Az. | Time | Alt. | Az. | ||
| 27 Jun | -3.6 | 4:01:58 | 32 | WSW | 4:03:17 | 63 | NW | 4:06:36 | 10 | NE |
| 28 Jun | -3.4 | 3:14:52 | 60 | E | 3:14:52 | 60 | E | 3:17:46 | 10 | NE |
| 30 Jun | -2.8 | 3:13:16 | 40 | NW | 3:13:21 | 40 | NNW | 3:16:31 | 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°.
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 west at 9:30 p.m. on June 25, 2023. Credit: Stellarium, EG
Looking Southeast at 4:30 a.m. on June 26, 2023. Credit: Stellarium, EG
This week, four naked eye planets will be visible. Venus and Mars are found in the west after sunset. Saturn and Jupiter are visible in the southeast and east before sunrise.
Venus
Venus is well into its current evening apparition. Venus will be a bright target in the west after sunset until August 2023 when it approaches inferior conjunction. This week, look for Venus in the west about 20 minutes after sunset. Venus sets at 11:00 p.m.
Mars
Mars now rises before sunset, becoming visible once it is dark. Look for it high in the west about 30 minutes after sunset. Mars sets at 11:12 p.m.
Jupiter
Jupiter is starting another apparition. Jupiter rises at 2:29 a.m. About one hour after Jupiter rises, it should be easy to spot. Jupiter will rise about 20 minutes earlier each week.
Saturn
Saturn rises at 11:56 p.m. Start looking for Saturn about 30 minutes after it rises. 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.
James S. McDonnell Planetarium
Night Sky Update: June 24- July 2, 2023