This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, June 19. 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, July 6, 2018 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 5:38 a.m. on Tuesday, June 26 and sunset is at 8:30 p.m. providing us with roughly 15 hours of daylight. Even after sunset, the light from the sun will still dimly illuminate our sky for 2 hours. This period of time is called twilight, which ends around 10:27 p.m. this week. For those with a sun dial, solar transit or local noon occurs around 1:04 p.m. this week.

Day

Sunrise

Sunset

26 Jun

5:38 a.m.

8:30 p.m.

27 Jun

5:39 a.m.

8:30 p.m.

28 Jun

5:39 a.m.

8:30 p.m.

29 Jun

5:39 a.m.

8:30 p.m.

30 Jun

5:40 a.m.

8:29 p.m.

01 Jul

5:40 a.m.

8:29 p.m.

02 Jul

5:41 a.m.

8:29 p.m.

03 Jul

5:41 a.m.

8:29 p.m.

04 Jul

5:42 a.m.

8:29 p.m.

Moonrise  for Tuesday, June 26 occurs at 7:14 p.m. and moonset will occur at 5:19 a.m. on the following day. On Tuesday, June 26 the moon will be exhibiting a waxing gibbous phase with roughly 98% of the lunar disk illuminated. Full moon occurs on June 27. June’s full moon is often called the Strawberry Moon.

International Space Station (ISS) Observing
Visible passes of ISS from St. Louis for the week of June 26 occur in the morning hours. The best of these occur on the mornings of July 3 and 4. Use the table below for information about these and other visible passes of ISS this week.

Catch ISS from St. Louis starting Tuesday, June 26

Mag

Starts

Max. altitude

Ends

Time Alt. Az. Time Alt. Az. Time Alt. Az.
01 Jul -3.1 05:01:24 10 SSW 05:04:34 47 SE 05:07:45 10 ENE

02 Jul

-2.1 04:11:03 17 S 04:12:32 23 SE 04:15:14 10 ENE

03 Jul

-3.6 04:53:37 12 WSW 04:56:40 64 NW 04:59:56 10 NE

04 Jul

-3.7 04:03:28 38 SSW 04:04:30 62 SE 04:07:45 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°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

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 Planets Visible Without a Telescope

This week all five of the naked eye planets are visible. Mercury and Venus bright objects in the west after sunset, Jupiter is visible after sunset in the south, Saturn is in the southeast a little after sunset and Mars is still best after midnight.

Mercury

Mercury can be a tough planet to see because it does not elongate too far from the sun before it heads back to the sun’s glare. Mercury is starting one of its best apparitions for 2018. This evening apparition will be at its best on July 12 as Mercury reaches greatest eastern elongation on this night.

Right now Mercury can be see about 8° above the western horizon 30 minutes after sunset. If you have trouble finding Mercury in the twilight sky grab some binoculars and scan the horizon. If you do this make sure the sun has set so you do not accidentally look at the sun.

Venus

The second planet from the sun is climbing out of the sun’s glare. Typically the 30 minute mark after sunset is what we use to determine if a planet is visible yet. Using this approach Venus will be about 20° above the western horizon around 9:00 p.m.

The evening apparition of Venus that is starting will last all the way through October 2018. So for most of the year Venus will be an early evening target. Another observing note is that Venus will start in a gibbous phase and end this apparition in a crescent phase. Planets that are closer to the sun than we are exhibit phases like the moon does. As the apparition progresses Venus will grow brighter because it will be getting closer to Earth. On October 26 Venus will reach inferior conjunction which is when Venus passes between the Earth and Sun.

Mars

The red planet has started another apparition and can be found rising in the east by 10:48 p.m. Due to trees and buildings most of us will start to see Mars closer to 12:00 a.m. Each week Mars will rise a little earlier than the week before as we approach the 2018 Mars opposition which occurs on July 27.

If you want to start preparing for the upcoming 2018 Mars opposition follow this link: http://www.alpo-astronomy.org/jbeish/2018_MARS.htm

Jupiter

The king of the planets can rises before the sun sets. Start looking for it high in the south about 30 minutes after sunset. Jupiter will set by 2:40 a.m.

Saturn

Saturn has been visible in the southern sky for some time now however the angle of the ecliptic in the early morning has kept the ringed planet low. Saturn is now rising as the sun is setting and will be an easy target by 10:00 p.m. however the ecliptic remains low in the southern sky. It is because of this that Saturn is still best after midnight.

This month Saturn will get brighter as it approaches opposition on June 27. After this date Saturn will be visible 30 minutes after sunset in the southeastern sky becoming a great late evening target.

Our next Star Party will be held on Friday, July 6, 2018, 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 July 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, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begin 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. Telescope viewing is scheduled to start around 7:00 p.m. however with the change to daylight saving time, darkness starts closer to 8:00 p.m.