This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, July 3, 2020.

Information updated weekly or as needed.

Times given as local St. Louis time (CDT).  For definitions of terminology used in the night sky update, click the highlighted text.

Star parties at the Saint Louis Science Center have been canceled due to recommendations from the CDC regarding COVID-19. All public telescope events are canceled until further notice. As conditions change, we will reevaluate and update this article once public observing events resume.

The Sun and Moon

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

Sunrise is at 5:38 a.m. on Friday, July 3 and sunset is at 8:30 p.m. providing us with about 15 hours of daylight. Even after sunset, the light from the Sun will dimly illuminate our sky for roughly 2 hours. This period is called twilight, which ends around 10:25 p.m. this week. For those with a sundial, local noon occurs around 1:05 p.m. this week.

2020-06-03 5:42 a.m.8:29 p.m.
2020-06-04 5:42 a.m.8:29 p.m.
2020-06-05 5:43 a.m.8:29 p.m.
2020-06-06 5:43 a.m.8:28 p.m.
2020-06-07 5:44 a.m.8:28 p.m.
2020-07-08 5:45 a.m.8:28 p.m.
2020-07-09 5:45 a.m.8:27 p.m.
2020-07-10 5:46 a.m.8:27 p.m.
2020-07-11 5:46 a.m.8:27 p.m.

Moonrise for Friday, July 3 occurs at 7:21 a.m. and moonset will occur at 4:59 a.m. on the following day. On Friday, July 3 the Moon will exhibit a waxing gibbous phase with about 98% of the lunar disk illuminated. Full moon occurs on July 3 at 23:44 p.m.

Penumbral Lunar Eclipse July4/5

Starting on July 4 and ending after midnight on July 5 is a penumbral lunar eclipse. A penumbral lunar eclipse occurs when the full moon passes through Earth’s penumbral shadow. This is the lighter part of Earth’s shadow and as such there will only be a slight dimming of the northern limb of the Moon. The eclipse begins at 10:08 p.m. and ends at 12:53 a.m. Greatest eclipse occurs at 11:31 p.m.

International Space Station (ISS) Observing

Credit: NASA

Visible passes of ISS from St. Louis for the week of July 3 occur during morning hours. The best of these occur on the mornings of July 4 and 6. Use the table below for information about these and other visible passes of ISS.

Catch ISS from St. Louis starting Friday, July 3

Date Starts  Max. altitude  Ends  
03 July-2.8 03:20:5838NW 03:21:1439NNW 03:24:2510NE
04 July-2 02:34:4032NE 02:34:4032NE 02:36:3910NE
04 July-1 04:08:3710NW 04:10:3514NNW 04:12:3310NNE
05 July-0.7 01:48:2013ENE 01:48:2013ENE 01:48:4410NE
05 July-1.5 03:21:1416NW 03:22:2719NNW 03:24:5710NNE
06 July-1.7 02:34:5025NNW 02:34:5025NNW 02:37:1810NNE
07 July-1 01:48:2419NNE 01:48:2419NNE 01:49:3310NE
08 July-1 02:34:4614NW 02:35:3915NNW 02:37:3810NNE
09 July-1 01:48:1118N01:48:1118N 01:50:0110NNE
09 July-0.6 05:01:4210NNW 05:03:2013NNE 05:04:5910NE
10 July-0.7 01:01:3215NNE 01:01:3215NNE 01:02:1810NNE
11 July-1 05:01:5610NNW 05:04:3822NNE 05:07:1910E

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 Visible Planets

Looking South, at 1:00 am, July 4, 2020
Credit: Stellarium, EG

Looking East and South, 4:30 am, July 4, 2020
Credit: Stellarium, EG

This week, four naked eye planets are visible in the morning. Jupiter and Saturn rise in the evening but are better seen after midnight. Look for them rising in the southeast and after midnight they will be in the south. Mars will be best seen in the southeast a few hours before sunrise and Venus will be low to the east just before sunrise.

For those tracking Jupiter and Saturn as they approach their great conjunction later this year, the two gas giants currently appear about 6.4° apart in the sky. Jupiter appears to be moving away from Saturn right now due to retrograde motion. This is all an illusion caused by Earth passing by slower moving Jupiter. Saturn has also started retrograde motion. If you keep watching these planets as 2020 progresses, you will see some interesting behaviors that inspired early astronomers to track the skies.


Venus has begun another morning apparition. After months of seeing Venus in the west after sunset Venus is now visible in the east before sunrise. By 4:30 a.m. Venus will be 10° above the eastern horizon. Venus remains a morning object until March 26, 2021 when it reaches superior conjunction.  Venus reaches maximum western elongation on August 12, 2020.


The red planet rises around 12:33 a.m. and will be high enough to see in the southeast by 1:30 a.m. Opposition for Mars occurs on October 13, 2020. As we head towards this date Mars will appear brighter and larger through a telescope improving surface details. Surface features are already visible when viewing conditions are favorable.


The king of the planets is rising around 9:02 p.m. and should be visible in the southeast around 10:00 p.m. Each week you will find Jupiter rising roughly 30 minutes earlier than it did in the previous week. Opposition for Jupiter occurs on July14. On this date Jupiter will be at its brightest for the 2020 apparition. After this date Jupiter will rise before the Sun sets.


Saturn is rising around 9:23 p.m. and will be visible in the southeast around 10:30 a.m. Saturn reaches opposition on July 20. For those with a telescope keep track of the orientation of Saturn’s rings.  Since Saturn is tilted on its rotational axis, we cross the plane of Saturn’s ring every 13 to 15 years.  We are headed towards another ring plane crossing on March 23, 2025. Over the next five years you will notice Saturn’s rings will gradually incline towards an edge on appearance.

2020 Great Conjunction

This year the planets Jupiter and Saturn will reach conjunction.  A conjunction is when two or more celestial bodies share the same right ascension.  For Jupiter and Saturn this astronomical event occurs every 20 years. The conjunction occurs on December 21, 2020.  You will find the two planets close together in the southwest just after sunset on this date.

Visit the James S. McDonnell Planetarium for more information on what’s up!

Night Sky Update: July 3-July 11, 2020