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 5:36 a.m. on Tuesday, June 19 and sunset is at 8:28 p.m. providing us with nearly 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 10:26 p.m. this week. For those with a sun dial, solar transit or local noon occurs around 1:02 p.m. this week.

This week on June 21 summer officially begins. This day is called the summer solstice which will be the longest day of the year. During summer we are tilted towards the sun which is why the northern hemisphere will get warmer. More hours of direct sun exposure means the temperatures rise. Contrary to popular belief this is not when we are closest to the sun. On July 6 this year Earth reaches aphelion which is when we are at our greatest distance from the sun. This distance is about 95 million miles. Learn more about the Earth’s seasons.

Day

Sunrise

Sunset

19 May

5:36 a.m.

8:28 p.m.

20 May

5:37 a.m.

8:29 p.m.

21 May

5:37 a.m.

8:29 p.m.

22 Jun

5:37 a.m.

8:29 p.m.

23 Jun

5:37 a.m.

8:29 p.m.

24 Jun

5:38 a.m.

8:29 p.m.

25 Jun

5:38 a.m.

8:29 p.m.

26 Jun

5:38 a.m.

8:30 p.m.

27 Jun

5:39 a.m.

8:30 p.m.

Moonrise  for Tuesday, June 19 occurs at 12:11 p.m. and moonset will occur at 1:16 a.m. on the following day. On Tuesday, June 19 the moon will be exhibiting a waxing crescent phase with roughly 42% of the lunar disk illuminated. First quarter moon occurs on June 20.

International Space Station (ISS) Observing
There are no visible passes of ISS from St. Louis until July 1. This week we will look for the Hubble Space Telescope. HST will be visible a few times this week. Use the table below for information about visible passes of HST this week.

Catch HST from St. Louis starting Tuesday, June 19

Mag

Starts

Max. altitude

Ends

Time Alt. Az. Time Alt. Az. Time Alt. Az.

19 Jun

2.8 21:17:43 10 SW 21:19:57 14 SSW 21:22:10 10 SSE

20 Jun

3.0 21:07:44 10 SW 21:09:29 12 SSW 21:11:14 10 S

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 we only four of the naked eye planets remain visible. Venus remains a brilliant object in the west after sunset, Jupiter is visible after sunset in the south, Saturn is best after midnight and Mars is still best after 1:00 a.m.

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 21° above the western horizon around 9:00 p.m. Those with a clear western horizon should be able to see Venus soon after sunset in the west.

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 11:13 p.m. Due to trees and buildings most of us will start to see Mars closer to 12:30 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 3:08 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 by 8:52 p.m. and will be an easy target by 10:30 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.