Night Sky Update For The Week of July 17, 2018

 In Night Sky Update, Planetarium
Night Sky Update For The Week of July 17,  2018

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, July 17. 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 3, 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 5:50 a.m. on Tuesday, July 17 and sunset is at 8:24 p.m. providing us with about 15 hours of daylight. Even after sunset, the light from the sun will still dimly illuminate our sky for roughly 2 hours. This period of time is called twilight, which ends around 10:15 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

17 Jul

5:50 a.m.

8:24 p.m.

18 Jul

5:51 a.m.

8:23 p.m.

19 Jul

5:52 a.m.

8:22 p.m.

20 Jul

5:53 a.m.

8:22 p.m.

21 Jul

5:53 a.m.

8:21 p.m.

22 Jul

5:54 a.m.

8:20 p.m.

23 Jul

5:55 a.m.

8:20 p.m.

24 Jul

5:56 a.m.

8:19 p.m.

25 Jul

5:57 a.m.

8:18 p.m.

Moonrise for Tuesday, July 17 occurs at 11:04 a.m. and moonset will occur at 11:50 p.m. On Tuesday, July 17 the moon will be exhibiting a waxing crescent phase with roughly 28% of the lunar disk illuminated. First quarter moon occurs on July 19.

International Space Station (ISS) Observing
Visible passes of ISS from St. Louis for the week of July 17 occur in the morning and evening hours. The best of these occur on the morning of July 20 and on the evenings of July 20 and 22. Use the table below for information about these and other visible passes of ISS this week.

The last pass on July 18 will be an unusual pass. ISS will appear and then quickly enter Earth’s shadow only to come back into view a few minutes later above the opposite horizon. In many years of viewing ISS transit the sky I have never seen this.

Catch ISS from St. Louis starting Tuesday, July 17

Mag

Starts

Max. altitude

Ends

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

17 Jul

-0.5 00:51:04 13 N 00:51:04 13 N 00:51:51 10 NNE

17 Jul

-0.6 04:03:07 10 NNW 04:04:57 14 NNE 04:06:48 10 NE

18 Jul

-2.0 04:46:37 10 NW 04:49:41 35 NNE 04:52:44 10 E

18 Jul

-2.5 21:26:03 10 S 21:28:35 21 SE 21:29:59 16 E

18 Jul

-1.9 23:01:48 10 WSW 23:06:17 24 NNE 23:07:59 10 NE

19 Jul

-1.1 03:55:30 10 NNW 03:58:11 22 NNE 04:00:51 10 E

19 Jul

-3.6 22:10:18 10 WSW 22:13:33 71 NW 22:16:50 10 NE

19 Jul

-0.5 23:48:38 10 NW 23:50:33 14 NNW 23:52:27 10 NNE

20 Jul

-0.6 03:03:43 10 NNW 03:05:50 16 NNE 03:07:57 10 ENE

20 Jul

-3.8 04:39:27 10 NW 04:42:45 86 NE 04:46:01 10 SE

20 Jul

-3.8 21:18:16 10 SW 21:21:28 56 SE 21:24:41 10 ENE

20 Jul

-1.0 22:55:39 10 WNW 22:58:10 20 NNW 23:00:42 10 NNE

21 Jul

-2.6 03:47:25 10 NW 03:50:35 44 NE 03:53:44 10 ESE

21 Jul

-1.8 22:02:54 10 W 22:05:52 30 NNW 22:08:50 10 NE

22 Jul

-1.6 02:55:29 10 NNW 02:58:20 26 NNE 03:01:10 10 E

22 Jul

-3.2 04:31:49 10 WNW 04:34:51 34 SW 04:37:52 10 SSE

22 Jul

-3.0 21:10:25 10 WSW 21:13:38 54 NW 21:16:51 10 NE

22 Jul

-0.5 22:49:05 10 NW 22:50:42 13 NNW 22:52:19 10 NNE

23 Jul

-0.7 21:55:57 10 WNW 21:58:15 17 NNW 22:00:34 10 NNE

24 Jul

-1.4 21:03:05 10 W 21:05:54 26 NNW 21:08:43 10 NNE

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 four of the naked eye planets are visible. Venus is 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 11:00 p.m.

Mercury

Mercury is now seen only 4.7° above the western horizon 30 minutes after sunset. One of Mercury’s best apparitions for 2018 is coming to an end. If you can find a clear view of the western horizon you might still find Mercury but for most of us this apparition has come to an end.

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 16° above the western horizon around 9:00 p.m.

The evening apparition of Venus that is underway will last all the way through October 2018. 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.

Venus and Mercury both exhibit phases like the moon does. This is due to them being closer to the Sun than Earth is. This is also why we only see these planets just after sunset or just before sunrise. Venus is exhibiting a gibbous phase with about 63° of the disk of Venus illuminated. This will decrease as the year goes on. Small telescopes and large binoculars will reveal the phases of Venus.

Mars

The red planet has started another apparition and can be found rising in the east by 9:25 p.m. Due to trees and buildings Mars will be best seen after 11:00 p.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 rises before the sun sets. Start looking for it high in the south about 30 minutes after sunset. Jupiter will set by 1:16 a.m.

Saturn

Saturn has been visible in the southern sky for some time now however the angle of the summertime ecliptic will keep the ringed planet low in the southern sky. However, Saturn now rises before sunset so if you have a clear southeastern sky you should be able to spot Saturn by 10:00 p.m.

Our next Star Party will be held on Friday, August 3, 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 August 3, 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.

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