Night Sky Update: August 24-September 1, 2024 - Saint Louis Science Center (2024)

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Saturday, August 24, 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, September 6, 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

Hubble view of Saturn’s ring plane crossing in 1995. Image credit: Top photo: Reta Beebe (New Mexico State University), D. Gilmore L. Bergeron (ST ScI) and NASA.Bottom photo: Amanda S. Bosh (Lowell Observatory), Andrew S. Rivkin (Univ. of Arizona/LPL), the HST High Speed Photometer Instrument Team (R.C. Bless, PI), and NASA.

Planets are finally returning to our evening sky. For several months our only opportunity to see planets was in the early morning before sunrise. There were a few evening apparitions of Mercury, but only the July apparition was high enough for most to see. As we reach the end of August, Venus is finally becoming visible in the west after sunset and Saturn is now visible around 10 pm.

Saturn is the easiest to find this week. It rises around 8:20 p.m. Depending on your view to the southeast, Saturn should clear tree lines by 9:30 p.m. or 10:00 p.m. As the night progresses, Saturn will climb high in the southern sky shifting to the southwest by early morning. If you have a telescope at home and have not looked at Saturn lately, you may be surprised when you see its rings are appearing nearly edge on. Like Earth, Saturn’s rotational axis is tilted and as such it exhibits seasons. Saturn takes about 29.4 years to complete one cycle of seasons. As Saturn approaches an equinox, the tilt of Saturn’s rings will continue to decrease until a ring plane crossing. Saturn’s next equinox is May 6, 2025, and the next ring plane crossing is March 25, 2025. Unfortunately, it occurs just days after Saturn reaches superior conjunction so it will be lost from view due to the Sun’s glare.

Saturn will be at its best through September this year as it reaches opposition on September 7, 2024. Opposition occurs when Saturn appears opposite the Sun when viewed from Earth. This normally happens once a year for Saturn and it’s when the planet appears its brightest.

Venus for most is still a little low to the horizon but that will change as we start September. Right now, Venus appears about 7° above the horizon 15 minutes after sunset. At this time, it will still be bright outside, and it will be lost to most tree lines. If you can find a place with a clear view down to the horizon, you should be able to spot Venus.

Venus is just starting an evening apparition. This means it is slowly climbing higher above the western horizon after sunset until it reaches greatest eastern elongation on January 9, 2025. After this, Venus’s elongation will decrease until we loose it to the glare of the Sun in March 2025. Venus next reaches inferior conjunction on March 22, 2025. As we near this date, you will see Venus exhibit thinner crescent phases each day until it is lost in the Sun’s glare.

Jupiter will be the next evening planet but that will not occur until closer to November. Mars will follow suit as we approach the end of the year. Soon our early evening sky will be full of planets again.

The Sun and Moon

The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA

Sun

Sunrise is at 6:23 a.m. on Saturday, August 24 and sunset is at 7:42 p.m. providing about 13 hours of daylight by the end of the week. 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 9:17 p.m. this week. For those with a sundial, local noon occurs around 1:03 p.m. on August 24, 2024.

Moon

Moonrise for Saturday, August 24 was at 10:31 p.m. and moonset occurred at 1:27 p.m. the following day. On Saturday, August 24, the Moon will exhibit waning gibbous phase with 67% disk illumination. By the end of the week the Moon will exhibit a waning crescent phase with 1% disk illumination. Last quarter moon occurs on August 26, 2024, at 4:26 a.m.

International Space Station (ISS) Observing

There are several visible passes of ISS from St. Louis for the week of August 24. They occur during 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:

http://www.jpl.nasa.gov/

The Visible Planets

Looking southeast at 10:00 p.m. on August 25, 2024. Credit: Stellarium, EG

Looking southeast at 2:00 a.m. on August 26, 2024. Credit: Stellarium, EG

This week, three naked eye planets are visible while a fourth is slowly entering an evening apparition. Mars and Jupiter are visible in the east before sunrise. Saturn will be visible in the southeast by midnight. Venus is still too low to easily find but it will be visible in the west after sunset by the end of the month.

Mars

This week, three naked eye planets are visible while a fourth is slowly entering an evening apparition. Mars and Jupiter are visible in the east before sunrise. Saturn will be visible in the southeast by 10pm. Venus is still too low to easily find but it will be visible in the west after sunset by the end of the month.

Mars

Mars rises at 12:54 a.m. and should be visible around 2:00 a.m. If you watch Mars for the rest of the year, you will see Mars and Jupiter moving apart. This is happening because Mars moves faster in its orbit.

Jupiter

Jupiter can now be found low to the east just before sunrise. Jupiter rises around 12:33 a.m., becoming visible after 1:30 a.m.

Saturn

Saturn rises near 8:20 p.m., becoming visible closer to 10:00 p.m. By 3:00 a.m., you can find Saturn in the south. Saturn will continue to get brighter as the planet approaches opposition. Opposition for Saturn occurs on September 7, 2024.

Our next Star Party will be held on Friday, September 6, 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 September 6, 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: August 24-September 1, 2024