This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, March 1, 2025.
Information updated weekly or as needed.
Times given as local St. Louis time this week will be in Central Standard Time (CST) until March 8, 2025. Daylight Saving Time begins on March 9, 2025. On this date, local St. Louis times will be posted 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 -6 hours when CST and -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, March 7, 2025, held in association with the St. Louis Astronomical Society.
Observing Highlight of the Week
On March 8, 2025, Mercury and Venus will be seen together in the west about 20 minutes after sunset. Image created using Stellarium.
For the next few weeks, Mercury can be found low in the west after sunset. This is the first evening apparition of the year for Mercury. It is not the best for 2025, But Mercury is easy to see now about 20 to 30 minutes after sunset.
Maximum eastern elongation occurs on March 8, 2025. On this date, Mercury’s solar elongation will be a little over 18°. About 20 minutes after sunset, Mercury will appear about 10° above the western horizon. If you find your western view is obscured by trees or buildings, find a large parking lot with a western view.
Mercury reaches dichotomy on March 7, 2025. For those with telescopes, this is when you will see half of the disk of Mercury illuminated. After this, Mercury shifts into crescent phases as it approaches inferior conjunction on March 24, 2025.
Contrary to Venus, Mercury is brightest when exhibiting gibbous phases. Mercury’s magnitude is already decreasing. Even though it is dimming, Mercury will remain an easy naked eye target for the next 10 days or so.
Each day after elongation, Mercury will appear nearer the Sun making it more difficult to find. After March 8th you should be cautious when looking for Mercury. Make absolutely sure the Sun has set before looking for it.
Mercury’s next morning and evening apparitions are the best of 2025. Both reach elongations over 20°. The next morning apparition reaches maximum western elongation on April 21, 2025. Early birds should be on the lookout for Mercury the last half of April.
T CrB Nova Update 3/2/2025
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 10.0.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sun
Sunrise is at 6:32 on Saturday, March 1 and sunset is at 17:54 providing roughly 11.5 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 19:23 this week. For those with a sundial, local noon occurs around 12:14 on March 1, 2025.
Daylight Saving Time begins on March 9, 2025, at 02:00. Make sure to set your clocks one hour forward when you go to bed on March 8, 2025.
Moon
Moonrise for Saturday, March 1, was at 07:27 and moonset occurred at 20:11. The Moon starts the week off with a waxing crescent phase exhibiting 5% disk illumination. By the end of the week the Moon will exhibit a waxing gibbous phase with 82% disk illumination. First quarter moon occurs on March 6, 2025, at 10:32.
International Space Station (ISS) Observing
Passes of ISS visible from St. Louis for the week of March 1, occur in early morning hours. The table below lists 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.
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 18:20 on March 2, 2025. Credit: Stellarium, EG
This week, four naked eye planets are visible. All three are visible in the evening sky not long after sunset.
Mercury
Mercury’s first evening apparition is well underway. The closest planet to the Sun should be easy to spot over the next couple of weeks. Greatest elongation occurs on March 8, 2025. You can find Mercury about 20 to 30 minutes after sunset in the west. Look for it to be about 10° above the western horizon. Mercury sets around 19:00 this week. Mercury reaches inferior conjunction March 24, 2025.
Venus
Venus will be visible in the southwest after sunset. You can start looking for Venus about 15 minutes after the Sun sets. Venus will set by 20:18. Venus is now headed towards inferior conjunction which occurs on March 22, 2025. Over the next couple of months, Venus will continue to appear closer to the Sun until we lose Venus to the Sun’s glare.
Mars
Mars is now past opposition. Look for it nearly overhead after sunset. 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 04:00 this week.
Jupiter
Now past opposition, Jupiter rises before the Sun sets. Look for Jupiter overhead as the sky begins to darken. Jupiter sets around 01:00.
Our next Star Party will be held on Friday, March 7, 2025, from 5:30 pm until 8:30 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 March 7, join us indoors in our planetarium theater for our “Monthly Sky Lecture”. Showtime is at 7 p.m. This free, indoor star program will introduce you to the current night sky. Doors open 15 minutes before show time. Shows begins at 7 pm Sorry, no late admissions due to safety issues in the darkened theater.
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: March 1-9, 2025
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