This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, August 1.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, August 4, 2017 held in association with the St. Louis Astronomical Society.  For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:03 a.m. on Tuesday, August 1 and sunset is at 8:11 p.m. providing us with about 14 hours of daylight.  Even after sunset, the light from the sun will still dimly illuminate our sky for a bit less than 2 hours.  This period of time is called twilight, which ends around 9:56 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:07 p.m. this week.

Day Sunrise Sunset
 01 Aug 6:03 a.m. 8:11 p.m.
 02 Aug 6:04 a.m. 8:10 p.m.
 03 Aug 6:04 a.m. 8:09 p.m.
 04 Aug 6:05 a.m. 8:08 p.m.
 05 Aug 6:06 a.m. 8:07 p.m.
 06 Aug 6:07 a.m. 8:06 p.m.
 07 Aug 6:08 a.m. 8:04 p.m.
 08 Aug 6:09 a.m. 8:03 p.m.
 09 Aug 6:10 a.m. 8:02 p.m.

Moonrise for Tuesday, August 1 occurs at 3:24 p.m. and moonset will occur at 1:54 a.m. on the following day.  On Tuesday, August 1 the moon will be exhibiting a waxing gibbous phase with about 70% of the lunar disk illuminated.  Full moon occurs on August 7.  August’s full moon is often called the Full Sturgeon Moon.

International Space Station (ISS) Observing

Visible passes of ISS from St. Louis for the week of August 1 occur in the evening hours.  The best of these occur on the evenings of August 7, 8 and 9.  Use the table below for information about these and other visible passes of ISS this week.

Catch ISS flying over St. Louis starting Tuesday, August 1

Mag Starts Max. altitude Ends
Time Alt. Az. Time Alt. Az. Time Alt. Az.
02 Aug -0.6 23:30:17 10 NNW 23:30:58 14 NNW 23:30:58 14 NNW
03 Aug -1.3 22:38:16 10 NNW 22:40:21 17 NNE 22:40:21 17 NNE
04 Aug -1.1 21:46:21 10 NNW 21:47:57 13 NNE 21:49:30 10 NE
04 Aug -0.6 23:21:47 10 NW 23:22:23 14 NW 23:22:23 14 NW
05 Aug -2.0 22:29:35 10 NW 22:31:48 27 N 22:31:48 27 N
06 Aug -1.8 21:37:30 10 NNW 21:39:59 20 NNE 21:41:14 16 NE
06 Aug -0.6 23:13:28 10 WNW 23:13:52 13 WNW 23:13:52 13 WNW
07 Aug -1.3 20:45:30 10 NNW 20:47:21 14 NNE 20:49:12 10 NE
07 Aug -2.6 22:21:04 10 NW 22:23:21 41 NNW 22:23:21 41 NNW
08 Aug -2.8 21:28:48 10 NW 21:31:51 36 NNE 21:32:51 28 ENE
09 Aug -2.0 20:36:38 10 NNW 20:39:18 23 NNE 20:41:57 10 E
09 Aug -2.4 22:12:46 10 WNW 22:15:03 34 W 22:15:03 34 W

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°.

For information about ISS flyovers and other visible satellites, visit

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

The Planets Visible Without a Telescope


Mercury is approaching the end of another evening apparition.  Typically you will want to look for Mercury at the end of civil twilight.  This week civil twilight ends around 8:40 p.m.  Greatest eastern elongation for Mercury was on July 30. This means the current apparition is coming to an end.  For the next couple of weeks Mercury will slowly wander closer to the twilight glow of the Sun.  Inferior conjunction occurs this month on August 26 so sneak a peek at the elusive planet while you still can.


The second planet from the sun can be found in the morning hours just before sunrise. Your best shot to see Venus is to find a clear eastern horizon view around 4:00 a.m.  Be careful though as you will be fighting the rising sun’s twilight glow.


Jupiter will be one of the first objects visible this week as the Sun’s light fades from the sky.  Look for it in the southwestern sky around 9:00 p.m.  Jupiter will set by 11:03 p.m. so it is an early evening target.


The king of the rings is visible once again.  You can find it at 9:00 p.m. by looking due south.  Saturn will set by 2:28 a.m.

Our next Star Party will be held on Friday, August 4, 2017, from dusk until 10 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 August 4, 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, the planets, and the seasonal constellations. 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.