This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, July 26, 2025.
Information updated weekly or as needed.
Times given as local St. Louis time this week will be in Daylight Saving Time. 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, August 1, 2025, 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 of the Week
The image above shows the location of the radiant for several meteor showers as seen from St. Louis, Missouri. Image created using Stellarium.
Each year around mid-July, Earth encounters a stream of debris deposited by a comet called 109P/Swift-Tuttle which last passed through the inner solar system in 1992. With an orbital period of 133 years, 109P/Swift-Tuttle will not be near Earth again until 2125. While it will be some time until the comet returns, most of the debris shed by the comet remains spread along the comet’s orbit. Because of this, each year around mid-July, Earth begins to pass through the debris from historic orbits of the comet producing the famous Perseid meteor shower.
Most good meteor showers occur in the last half of the year with the Perseids being the first in that time frame. While the Perseids are active, we have to wait until August 12-13 for the shower to peak and as such the number of meteors one will see remains low until that peak time frame.
While we wait for the peak of the Perseids, there are several other active meteor showers this week. Three other meteors showers that are active and peak this week are the Southern delta Aquarids, the alpha Capricornids and the July gamma Draconids. Of these only the Southern delta Aquarids is listed as a major meteor shower with the others being minor showers. Look for information about these meteor showers below.
When viewing meteors showers there are a few factors to consider. Light pollution is a factor that most are aware of. The more lights around you the less meteors will be seen. If you are viewing from a light polluted location, position yourself in a way that still provides a view of the sky while placing yourself in a location that allows buildings or tree lines to obscure lights in the immediate area. A second factors is also related to light pollution however it is a natural source. The current moon phase plays a major role in how dark the sky appears to us. For the Perseids this year, the Moon will be near its full moon phase and as such it will be a problem. During good years, from a dark location, the Perseids can produce upwards of 100 meteors per hour at peak activity. This year will be diminished do to the Moon phase. If viewing from a light polluted area, expect to see 5 to 10 per hour.
Another factor is location. Get to as dark a site as possible. From St. Louis, you want to drive about two hours away to find darker skies. If that is not possible, get as far from the city as you can. A good resource to find dark places is visit your local DarkSky Chapter. You can find the Missouri chapter at Missouri DarkSky. If you are not in Missouri, visit DarkSky International to find your states chapter.
Lastly, all meteors exhibit a radiant. This is the point in the sky which meteors appear to emanate from. If you ever see a meteor streaking across the sky, its path will trace back to the radiant if the meteor is from a specific meteor shower. You can visit the American Meteor Society to figure out what showers are active on a given night. On this website you will find basic sky maps that indicate the radiant location of any active meteor shower. A radiant is typically named after the constellation contains it or in some cases the bright star it appears next to.
Southern delta Aquarids
This meteor shower is active from July 18 to August 12. Its parent object is thought to be comet 96P/Machholz. The peak of this meteor shower occurs on July 30, 2025. While this shower can produce 25 meteors per hour, it favors southern hemisphere viewers. From St. Louis, we will see a limited display in our southern sky as the constellation moves from southeast to the southwest of the course of a night.
alpha Capricornids
This meteor shower is active from July 7 to August 13 each year. Its peak activity occurs on July 30, 2025. During peak activity this meteor shower is expected to produce about 5 meteors per hour. The radiant for the alpha Capricornids is found in the constellation Capricornus. This constellation rises this week around 21:00 in the southeast. The parent body of this meteor shower is comet 169P/NEAT.
July gamma Draconids
This minor meteor shower is active from July 23 to August 3. Peak activity occurs on July 28 with a maximum rate of one meteor per hour. While this does not sound that great, this shower exhibited an outburst in 2016 that lasted about one hour. The radiant for this minor meteor shower is located in the constellation Draco near the 2nd magnitude star gamma Draconis. You can find Draco in our northern sky between the Big and Little Dippers. The parent body for this meteor shower remains unknown.
T CrB Nova Update 7/27/2025
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. It could happen this year or it could happen next year. We will have to wait and see. If you are still interested in this event, the part of the sky the nova will appear is overhead once it is dark. By 02:00, the constellation Corona Borealis will be found low in the western sky. Spaceweather.com is still posting magnitude estimates from the AAVSO. This is the resource I recommend following to keep up with any changes in the star’s brightness. Current magnitude of the system is 9.7.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sun
Sunrise is at 05:57 on Saturday, July 26 and sunset is at 20:17 providing about 14 hours of daylight. Even after sunset, light from the Sun will dimly illuminate our sky for about 2 hours. This period is called twilight, which ends around 22:19 this week. For those with a sundial, local noon occurs around 13:07 on July 26, 2025.
Moon
Moonrise for Saturday, July 26, was at 07:49 and moonset occurred at 21:41. On July 26, 2025, the Moon will exhibit a waxing crescent phase with 4% disk illumination. By August 4, 2025, the Moon will exhibit a waxing gibbous phase with 78% disk illumination. First quarter moon occurs on August 01, 2025, at 07:41 CDT.
International Space Station (ISS) Observing
Visible passes of ISS from St. Louis for the week of July 26 occur during morning and evening hours. The table above lists the best of these passes. 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.
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 west at 20:45 on July 27, 2025. Credit: Stellarium, EG
Looking east at 04:30 on July 28, 2025. Credit: Stellarium, EG
Three naked eye planets will be visible this week. Mars is visible in the west after sunset once it is dark. Venus and Saturn are visible before sunrise in the east.
Venus
Venus is found in the east before sunrise for the rest of the year. It currently rises around 03:00. Look for Venus in the east around 04:00 as it clears tree lines.
Mars
Look for Mars in the western sky after sunset. The current apparition of Mars will continue throughout the rest of 2025. As the year continues, Mars will slowly appear closer to the western horizon each night. Mars sets around 23:00.
Saturn
Saturn can be found in the east before sunrise. Saturn rises around 23:46 this week. The planet should be high enough to see by 01:00. If you missed the last Titan shadow transit, the next one occurs on July 18, 2025.
Our next Star Party will be held on Friday, August 1, 2025, from 6:30 pm until 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. Regardless of the weather on August 1, join us indoors in our planetarium theater for our free monthly sky lecture.
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 every Sunday through Labor Day from 11:00-15:00 weather permitting. 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: July 26-August 4, 2025
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