This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Sunday, May 11, 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, June 6, 2025, held in association with the St. Louis Astronomical Society.
Observing Highlight of the Week
T CrB Nova Update 5/11/2025
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 in is rising earlier each night. By midnight, the constellation Corona Borealis will be found high in the eastern 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 10.5.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sun
Sunrise is at 05:52 on Sunday, May 11 and sunset is at 20:02 providing over 14 hours of daylight. Even after sunset, light from the Sun will dimly illuminate our sky for about 1 hour and 40 minutes. This period is called twilight, which ends around 21:48 this week. For those with a sundial, local noon occurs around 12:58 on May 11, 2025.
Moon
Moonrise for Sunday, May 11, is at 19:29 and moonset occurs at 05:27 the following morning. On May 11, 2025, the Moon will exhibit a waxing gibbous phase with 99% disk illumination. By May 26, 2025, the Moon will reach new moon. Full moon occurs on May 12, 2025, at 11:56 CDT.
International Space Station (ISS) Observing
Visible passes of ISS from St. Louis for the week of May 11 occur during evening hours. The table below 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 south at 20:45 on May 11, 2025. Credit: Stellarium, EG
Looking east at 05:00 on May 12, 2025. Credit: Stellarium, EG
Four naked eye planets will be visible this week. Mars and Jupiter are visible after sunset once it is dark in the west. Venus and Saturn have returned to morning views becoming visible just before sunrise in the east.
Venus
Venus is well into a morning apparition and will continue to be found in the east before sunrise for the rest of the year. It currently rises around 04:00. Look for Venus in the east around 05:00 as it begins to clear tree lines.
Mars
Look for Mars overhead high in the western sky after sunset. Mars has shifted into the constellation Cancer. The current apparition of Mars will continue throughout the rest of 2025. Watch for the Red Planet as it shifts westward through the year. Mars sets around 01:30.
Jupiter
Jupiter will be visible in the west not long after sunset. Jupiter sets by 22:31, remaining visible for most up to 21:30. Jupiter reaches superior conjunction on June 24, 2025.
Saturn
Saturn can be found in the east before sunrise. Around 05:00, Saturn will appear roughly 14° above the eastern horizon and about 9° south of Venus.
Our next Star Party will be held on Friday, June 6, 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 June 6, join us indoors in our planetarium theater for a monthly 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 on the 3rd Sunday of 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: May 11-26, 2025
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