This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, June 12, 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.

For now, 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 5:36 a.m. on Friday, June 12 and sunset is at 8:26 p.m. providing us with close to 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 10:24 p.m. this week. For those with a sundial, solar transit or local noon occurs around 1:01 p.m. this week.

2020-06-12 5:36 a.m.8:26 p.m.
2020-06-13 5:36 a.m.8:27 p.m.
2020-06-14 5:36 a.m.8:27 p.m.
2020-06-15 5:36 a.m.8:28 p.m.
2020-06-16 5:36 a.m.8:28 p.m.
2020-06-17 5:36 a.m.8:28 p.m.
2020-06-18 5:36 a.m.8:28 p.m.
2020-06-19 5:37 a.m.8:29 p.m.
2020-06-20 5:37 a.m.8:29 p.m.

Summer Solstice 2020

The summer solstice for 2020 occurs on June 20 at 4:43 p.m. officially marking the beginning of summer. After June 20 days will grow shorter as the Sun gets lower in the sky each day. You can observe this behavior yourself by measuring the length of a shadow at local noon. The easiest way to do this is to find a nice sunny location and put rod into the ground. The rod acts as a shadow caster or what is called a gnomon.  Each day measure the rod’s shadow at local noon, and you will see the shadow gets longer until we reach the winter solstice in December. In ancient times astronomers observed the behavior of the Sun to keep time, know when to plant and harvest crops and to guide cultural behaviors.

Moonrise for Friday, June 12 occurs at 1:19 a.m. and moonset will occur at 12:19 p.m. On Friday, June 12 the Moon will exhibit a waning gibbous phase with about 54% of the lunar disk illuminated. Last quarter moon occurs on June 13 at 1:24 a.m.

International Space Station (ISS) Observing

Credit: NASA

There are no visible passes of ISS from St. Louis for the week of June 12. For those wanting to observe satellites this week I would encourage you to check out the free app from Heavens Above. Their app has several tools that are useful, but it is the section for nightly events that has become my go to tool for spotting and identifying satellites. After minimal setup, even those just getting started can explore the wide variety of satellites each night has to offer.

A new group of Starlink Satellites is scheduled to launch on June 13. The launch is scheduled to occur at 4:21 p.m. CDT. Live views of the launch should be available online through the live SpaceX streaming channels. Soon after a Starlink launch there are opportunities to see trains of satellites pass overhead. For those that have not seen one of these satellite trains they are impressive to see. Visit for more information.

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 West, at 9:00 pm, June 12, 2020
Credit: Stellarium, EG

Looking South, 3:30 am, June 13, 2020
Credit: Stellarium, EG

This week, four naked eye planets are visible. Mercury will be visible in the west about 40 minutes after sunset. Mars, Jupiter and Saturn are visible in the south and southeast in the morning hours before sunrise.

For those tracking Jupiter and Saturn as they approach their great conjunction later this year, the two gas giants currently appear about 5° apart in the sky.  If you keep watching them as 2020 progresses, you will see some interesting behaviors that inspired early astronomers to track the skies.


Mercury is ending the current evening apparition. Mercury reached greatest elongation on June 4 so Mercury will appear to head towards the Sun each day.  Mercury reaches inferior conjunction on June 30. Spotting Mercury will require a clear view of the western horizon.  At 9:00 p.m. Mercury will only be 8.6° above the horizon. After June 15 we can look forward to seeing Mercury before sunrise in July.


The red planet rises around 1:24 a.m. and will be high enough to see in the southeast by 2:20 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 10:36 p.m. and should be visible in the southeast around 11:30 p.m. Each week you will find Jupiter rising about 30 minutes earlier than it did in the previous week.


Saturn is rising around 10:54 p.m. Like Jupiter you will need a clear sky to the southeast to catch the ring planet around 12:00 a.m. Later this year Jupiter and Saturn will reach conjunction on December 21, 2020. You can track these planets as they appear to chase one another throughout the rest of this year.

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: June 12-June 20, 2020