This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, January 31.  All times are given as local St. Louis time (Central Standard 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, February 3, 2017 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 7:07 a.m. on Tuesday, January 31 and sunset is at 5:22 p.m. providing us with just under 10 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for a bit over 1.5 hours.  This period of time is called twilight, which ends around 6:53 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:14 p.m. this week.




 31 Jan

7:07 a.m.

5:22 p.m.

 01 Jan

7:06 a.m.

5:23 p.m.

 02 Jan

7:05 a.m.

5:24 p.m.

 03 Jan

7:05 a.m.

5:26 p.m.

 04 Jan

7:04 a.m.

5:27 p.m.

 05 Jan

7:03 a.m.

5:28 p.m.

 06 Jan

7:02 a.m.

5:29 p.m.

 07 Jan

7:01 a.m.

5:30 p.m.

 08 Feb

7:00 a.m.

5:31 p.m.

Moonrise for Tuesday, January 31 occurs at 9:18 a.m. and moonset will occur at 9:27 p.m.  On Tuesday, January 31 the Moon will be exhibiting waxing crescent phase with about 15% of the lunar disk illuminated.  First quarter moon occurs on January 31 at 10:19 p.m.

International Space Station (ISS) Observing

Visible passes of ISS from St. Louis for the week of January 31 occur in the evening hours.  The best of these occurs on the evening of February 1.  Use the table below for information about this and other visible passes of ISS this week.

Catch ISS flying over St. Louis starting Tuesday, January 31



Max. altitude


Time Alt. Az. Time Alt. Az. Time Alt. Az.
31 Jan -1.0 19:09:27 10 WNW 19:11:42 17 NNW 19:12:00 17 NNW
01 Feb -1.5 18:16:23 10 W 18:19:09 25 NNW 18:21:55 10 NNE
03 Feb -0.9 18:09:09 10 WNW 18:11:11 15 NNW 18:13:12 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

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:


The Planets Visible Without a Telescope


Venus can be seen low in the west about 20 minutes after sunset in the southwestern sky.  Venus sets by 9:05 p.m.


The Red planet is currently found in Pisces rising before the Sun and can be easily seen 30 minutes after sunset in the southwestern sky.  Mars sets by 9:29 p.m.


The largest planet in our solar system has started another apparition and can be found rising in the east at 11:10 p.m.  It is currently found in the constellation Virgo and is best seen between the hours of 12:00 a.m. and 6:00 a.m.


The king of the rings is visible once again shortly before the Sun rises.  Saturn rises at 4:12 a.m. so your best chance to see it will be around 6:30 a.m. low in the southeastern sky.  Unfortunately the glow of dawn will make things a little difficult.  Additionally trees and buildings may obscure your view.

Uranus and Neptune 2017

Both of the outer gas/ice giants are once again nicely placed in our evening skies.  Both have also reached opposition and as such will rise before the Sun sets.  Both planets will require binoculars to see and as such it will be best to wait until the end of twilight to start your search.  Uranus can be found in the constellation Piscis and Neptune is found in Aquarius.  The brighter of the two planets is Uranus shining with an apparent magnitude of 5.9.  Neptune’s apparent magnitude of 8.0 is within reach of binoculars but light pollution will make it difficult.  For up to date maps of the location of Uranus and Neptune follow the link below or use the free planetarium software Stellarium.

Constellation of the Month 2017

Over the last couple of years the night sky update has included information for locating a new deep sky object each week.  In 2017 we will change this by highlighting one constellation a month.  The first week of the month will always contain information regarding the constellation, its name, history and other such related topics.  Each week after will highlight a new object to look for.  A variety of objects will be highlighted but each month we will try to have an object that is visible through naked eye, binocular and telescope observations.

The constellation for the month of February is Gemini the Twins.  Located in the winter sky, Gemini will be easily seen in the east once twilight ends.  The constellation Gemini is easy to locate due to its location next to Orion the Hunter.  To find Gemini all you have to do is first locate Orion and follow a path from the stars Rigel to Betelgeuse and you will find a rectangle shape of bright stars to Orion’s northeast.  This rectangle shape of stars is the constellation Gemini.

The name Gemini is related to the Greek myth of the twins Castor and Pollux.  The twins shared a mother however their fathers were different.  Immortal Pollux was the son of Zeus and Castor was mortal son of King Tyndareus.  The twins were very close partaking on many adventures together.  They were part of the Argonauts that traveled with Jason and sadly it is during one of these adventures that the mortal Castor was slain.  Stricken with grief over the loss of his brother Pollux pleaded to join his brother in Hades.  Zeus agreed and placed him alongside his brother Castor in the sky so they could spend part of their time in Hades and part of the time with the rest of the Olympians in the sky.  Use the maps below for assistance in locating Gemini.

Our next Star Party will be held on Friday, February 3, 2017, 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 February 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 begins 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.