This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, May 4, 2024.
Information updated weekly or as needed.
Times given as local St. Louis time this week will be 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 -5 hours when CDT.
Join us for our next star party, Friday, June 7, 2024, 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
Map showing the location of the constellations, Ursa Majaor, Boötes and Corona Borealis. Inset map is showing the location of T CrB in relation to the bright stars of Corona Borealis. Maps created using Stellarium.
This week’s highlight is more of a reminder about an expected event that is likely to occur this spring or summer. Scientists expect we will soon see the eruption of the recurrent nova star T Coronae Borealis (T CrB). Recurrent novae are a rare type of variable star with only 10 well known examples with another possible recurrent nova appearing to be confirmed in 2022.
Recurrent novae are a type of eruptive variable in which a binary system comprised of a white dwarf and a red giant star. As they orbit each other, material from the red giant will funnel down to the white dwarf piling up into an accretion disk. As mass builds up, temperature and density increase eventually leading to a thermonuclear event. As the eruption occurs, the star will brighten significantly by several magnitudes. For the T CrB system its quiescence magnitude is 9.8 magnitude and its peak magnitude resulting from an eruption is 2.5. When the eruption occurs, T CrB will become bright enough to easily see with the unaided eye. After about 2 days to a week, T CrB will have noticeably dimmed. This is a target you will want to view nightly to ensure you have a chance to see this recurrent nova. T CrB’s eruption period is roughly 80 years so catch it while you can.
To find T CrB, you have to find the constellation Corona Borealis. This small constellation can be seen on the eastern edge of the larger constellation Boötes. The easiest way to find both of the constellations is to start at the Big Dipper. Looking high in the north once it is dark will reveal the large spoon shaped group of stars of the Big Dipper. Once you find this, follow the curve of the handle south until you find a bright orange star called Arcturus. This star appears near the bottom of a large kite shaped group of stars which is Boötes. Once here use the two stars that form the widest point of the kite and follow the direction they point to the east. Not far from them you will see a U-shape of stars which is Corona Borealis.
Once you find Corona Borealis, starting at the brightest star in the constellation called Alphecca (α CrB), count over three stars to the east to find the 4th magnitude star ε CrB. Once you have found this, T CrB will be about 1° to the southeast. Keep in mind, until the nova occurs, T CrB will require a telescope to see. The best thing to do while we monitor this area is to learn the dim star field around T CrB’s location. There are several 7th and 8th magnitude stars near T CrB that should be visible in moderate binoculars with moderate light pollution. To do this I would recommend using a star atlas or a desktop planetarium software such as Stellarium. It is best to use something that can display down to 9th magnitude stars.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sun
Sunrise is at 5:59 a.m. on Saturday, May 4 and sunset is at 7:56 p.m. providing roughly 14 hours of daylight this week. Even after sunset, light from the Sun will dimly illuminate our sky for about 1 hour and 45 minutes. This period is called twilight, which ends around 9:42 p.m. this week. For those with a sundial, local noon occurs around 12:57 p.m. on May 4, 2024.
| Day | Sunrise | Sunset | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4-May | 5:59 a.m. | 7:56 p.m. | ||||||||||
| 5-May | 5:58 a.m. | 7:57 p.m. | ||||||||||
| 6-May | 5:57 a.m. | 7:58 p.m. | ||||||||||
| 7-May | 5:56 a.m. | 7:59 p.m. | ||||||||||
| 8-May | 5:55 a.m. | 8:00 p.m. | ||||||||||
| 9-May | 5:54 a.m. | 8:01 p.m. | ||||||||||
| 10-May | 5:53 a.m. | 8:02 p.m. | ||||||||||
| 11-May | 5:52 a.m. | 8:03 p.m. | ||||||||||
| 12-May | 5:51 a.m. | 8:04 p.m. |
Moon
Moonrise for Saturday, May 4 was at 4:03 a.m. and moonset occurred at 4:07 p.m. On Saturday, May 4, the Moon will exhibit a waning crescent phase with roughly 15% disk illumination. By the end of the week the Moon will exhibit a waxing crescent phase with 25% disk illumination. New moon occurs on May 7, 2024, at 10:22 p.m.
International Space Station (ISS) Observing
There are several visible passes of ISS from St. Louis for the week of May 4. They occur during morning and evening 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.
Catch ISS from St. Louis starting Saturday, May 4, 2024
| Date | Starts | Max. altitude | Ends | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time | Alt. | Az. | Time | Alt. | Az. | Time | Alt. | Az. | ||
| 09 May | -3.8 | 5:18:07 | 10 | WNW | 5:21:24 | 59 | SW | 5:24:40 | 10 | SE |
| 09 May | -3.8 | 21:58:49 | 10 | SW | 22:01:55 | 76 | WSW | 22:01:55 | 76 | WSW |
| 10 May | -3.6 | 4:28:46 | 10 | NW | 4:32:06 | 73 | NE | 4:35:24 | 10 | ESE |
| 10 May | -3.6 | 21:09:37 | 10 | SSW | 21:12:50 | 49 | SE | 21:16:05 | 10 | ENE |
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 east at 5:00 a.m. on May 7, 2024. Credit: Stellarium, EG
This week, two naked eye planet are visible. Mars and Saturn are becoming visible in the east before sunrise, but trees may obscure their view.
Mars
Over the last month, Mars has slowly begun to climb out of the Sun’s glare. It is now rising early enough that you may find it in the east before sunrise. Start looking for Mars around 5:18 a.m.
Saturn
Saturn can be found in the east before sunrise. Saturn rises at 3:38 a.m. but you will want to give it about an hour to clear trees. Start looking for Saturn around 4:30 a.m.
Our next Star Party will be held on Friday, June 7, 2024, from dusk until 9 p.m.
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 June 7, join us indoors in our planetarium theater for “The Sky Tonight”. 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 p.m. 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 which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.
James S. McDonnell Planetarium
Night Sky Update: May 4, 2024