This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, February 22, 2025.
Information updated weekly or as needed.
Times given as local St. Louis time this week will be in Central Standard Time (CST). 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. 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.
Map showing the brightest stars of the constellation Corona Borealis. The star Epsilon CrB is indicated by the Greek letter “ε.” T CrB will appear about 1° south of the star. Image credit: IAU, Sky and Telescope.
Observing Highlight of the Week
New information regarding the recurrent nova T Coronae Borealis (T CrB) has been posted on the Astronomer’s Telegram indicating a change in the binary system’s spectrum. Observers have noted an increase in the intensity and width of the H-alpha emission from T CrB. Scientists believe this change could be a result of the accretion disk expanding due to an increased rate of accretion.
This change could be a sign that T CrB will soon go nova. A similar behavior was observed before recurrent nova RS Ophiuchi erupted in 2021. Due to this possibility, if you have not been tracking T CrB recently, it is time to start keeping an eye on it again.
Finding the location of this system has been getting easier as the weeks pass. T CrB is part of the constellation Corona Borealis (Northern Crown) which begins to rise around 22:00 (10pm). By roughly 23:00, the location of T CrB will be about 12° above the eastern horizon. The constellation Corona Borealis appears as a small U-shaped group of stars just east of the larger constellation Boötes.
Start by finding the constellation Boötes. Around 23:00, you will see a bright orange/red star called Arcturus. This is the brightest star in Boötes. Extending north from the star, you will see a group of stars that looks like a large kite which is Boötes. Locate the two stars at the widest point of the kite and follow the direction they point to the east. You will quickly see the U-shape of Corona Borealis. Once you can find this group, look for the star Epsilon CrB. T CrB will be found about 1° south of this star.
I recommend scanning this part of the sky nightly using binoculars. If the time frame is too late to do this every clear night, you can check spaceweather.com for daily updates of T CrB’s estimated magnitude. Normally the apparent magnitude of T CrB is 10.0 or higher. When the nova occurs, T CrB should become a 2nd magnitude star making it visible to the unaided eye. As of this posting, the estimated apparent magnitude of T CrB 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 6:51 on Saturday, February 22 and sunset is at 17:39 providing nearly 12 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 19:16 this week. For those with a sundial, local noon occurs around 12:15 on February 22, 2025.
Moon
Moonrise for Saturday, February 22, was at 3:00 and moonset occurred at 11:53. The Moon starts the week off with a waning crescent phase exhibiting 29% disk illumination. By the end of the week the Moon will exhibit a waxing crescent phase with 12% disk illumination. New moon occurs on February 27, 2025, at 18:45.
International Space Station (ISS) Observing
Passes of ISS visible from St. Louis for the week of February 22, 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 19:00 on February 23, 2025. Credit: Stellarium, EG
This week, three naked eye planets are visible. All three are visible in the evening sky not long after sunset..
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 20:41. 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 4:33 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 1:42.
Saturn
Unfortunately, for many observers, Saturn is likely lost to the Sun’s glare at this point. If you know where to look, you can still spot the planet with binoculars. This will become increasingly difficult as Saturn continues to appear lower to the western horizon each night. Any trees or buildings in that direction will likely obscure any views of Saturn. Saturn reaches superior conjunction on March 12, 2025.
Saturn and Mercury will reach conjunction on February 25, 2025. If you have a clear view of the west, you might still find Saturn near brighter Mercury about 7° above the western horizon around 18:10. You will need binoculars to have a chance of spotting the planets as this will be only 20 minutes after sunset. Before you look make sure the Sun has set before you look. Sunset on February 25, 2025, is at 17:50.
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: February 22-March 2, 2025
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