This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, January 17.  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 7:16 a.m. on Tuesday, January 17 and sunset is at 5:06 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 about 1.5 hours.  This period of time is called twilight, which ends around 6:39 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:11 p.m. this week.




 17 Jan

7:16 a.m.

5:06 p.m.

 18 Jan

7:16 a.m.

5:07 p.m.

 19 Jan

7:16 a.m.

5:09 p.m.

 20 Jan

7:15 a.m.

5:10 p.m.

 21 Jan

7:14 a.m.

5:11 p.m.

 22 Jan

7:14 a.m.

5:12 p.m.

 23 Jan

7:13 a.m.

5:13 p.m.

 24 Jan

7:13 a.m.

5:14 p.m.

 25 Jan

7:12 a.m.

5:15 p.m.

Moonrise for Tuesday, January 17 occurs at 10:51 p.m. and moonset will occur at 11:00 a.m. on the following day.  On Tuesday, January 17 the Moon will be exhibiting waning gibbous phase with about 71% of the lunar disk illuminated.  The first full moon of 2017 occurs on January 17 at 5:34 a.m.  Last quarter moon occurs on Thursday, January 19 at 4:13 p.m.

International Space Station (ISS) Observing

Visible passes of ISS from St. Louis for the week of January 17 occur in the morning hours.  The best of these occur on the mornings of January 17 and 18.  Use the table below for information about these and other visible passes of ISS this week.

Catch ISS flying over St. Louis starting Tuesday, January 17




Max. altitude


Time Alt. Az. Time Alt. Az. Time Alt. Az.
18 Jan -3.4 05:48:48 45 NW 05:49:40 88 NE 05:52:55 10 SE
19 Jan -1.0 04:59:00 24 E 04:59:00 24 E 05:00:35 10 ESE
19 Jan -1.4 06:31:41 11 W 06:33:41 17 SW 06:35:53 10 S
20 Jan -2.4 05:41:57 32 SSW 05:41:57 32 SSW 05:44:36 10 SSE
21 Jan -0.3 04:52:18 13 SE 04:52:18 13 SE 04:52:45 10 SE

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


Mercury starts 2017 off with a great morning apparition.  On January 19, Mercury will reach greatest western elongation appearing 24° from the Sun.  Currently Mercury rises about 1.5 hours before the Sun.  Due to this your best chance to see Mercury will be to go out around 6:30 a.m. and find a clear southeastern horizon.  Mercury will appear about 8° above the horizon at this time.


Venus can be seen low in the west about 20 minutes after sunset in the southwestern sky.  Venus sets by 8:56 p.m.


The Red planet is currently found in Aquarius rising before the Sun and can be easily seen 30 minutes after sunset in the southwestern sky.  Mars sets by 9:31 p.m.


The largest planet in our solar system has started another apparition and can be found rising in the east at 11:58 p.m.  It is currently found in the constellation Virgo and is best seen between the hours of 1:00 a.m. and 6:00 a.m.


The king of the rings is visible once again shortly before the Sun rises.  Saturn rises at 4:57 a.m. so your best chance to see it will be around 6:00 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 2016

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 5.8.  Neptune’s apparent magnitude of 7.9 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 January is Orion the Hunter.  Arguably the most famous constellation in the sky, Orion can be found in the east shortly after sunset this time of year.  Orion is easily identified by looking for three bright stars in a straight line which represent the belt he is known for.  Moving from east to west the belt stars are named Alnitak, Alnilam and Mintaka.  As the Earth rotates you will find these stars appearing to shift westward.  Around 6:00 p.m. Orion’s Belt can be found low in the east, around 10:00 p.m. it will be due south and near 3:00 a.m. it will be low in the West.  Once you learn to find Orion’s Belt you will notice four bright stars that form a rectangle around it.  The top two stars are named Betelgeuse and Bellatrix and the bottom two are Saiph and Rigel.

The name Orion is a familiar to many.  Orion is known as the great hunter from Greek mythology who was defeated by the giant scorpion named Scorpius.  Where many of us may know his Greek story his name is not of Greek origin but rather is Sumerian.  This ancient culture developed the first civilization, they were the first scientific astronomers and were the first to have a written language.  Their observations of the sky serves as the platform that modern astronomy stands on.  In Sumerian Orion’s name was Uru-anna meaning light of the sky.  Uru-anna was often associated with Taurus the Bull and the bright star Sirius.  Over time this ancient constellation would be passed down from culture to culture remaining an important reference in the sky.

For us today Orion remains one of the most recognizable patterns in the sky.  From him we can find numerous other constellations, stars and numerous deep sky objects.  Next week we will start our month of Orion observing with the bright and familiar star; Betelgeuse.

The first object in Orion we will explore is the Red Supergiant star Betelgeuse.  This bright red supergiant star is arguably one of the skies most well-known stars.  It is a monster of a star at 20 times the mass and 1,000 times the size of our Sun.  It is destined to explode in one of nature’s most violent events called a supernova.  It is one of the brightest stars in the sky standing 9th on the list of brightest stars in the sky.  All this after only existing for roughly 10 million years.  Betelgeuse’s time is fleeting due to its enormous size and mass.  Massive stars like Betelgeuse do not exist long due to their rate of fuel consumption.  Most stars are fueled by hydrogen which is smashed together in the heart of a star to produce helium and a bit of energy.  This is an over simplified description of nuclear fusion the process that enriches the universe in heavier elements.  Like all fuel sources the hydrogen at the core of a star becomes deleted inducing stellar evolution.  Betelgeuse has started these changes which will lead to its explosive end about 100,000 years ago.

Betelgeuse is thought to be about 600 light years away from the Sun.  An exact distance is difficult to find because Betelgeuse is unstable shedding the equivalent of the Sun’s mass in just 10,000 years.  This shed material forms clouds around Betelgeuse that hide the giant stars size making distance measurements difficult.  At its distance of approximately 600 light years Betelgeuse shines with an apparent magnitude of 0.42.  This apparent magnitude changes over time due to the stars unstable nature.  Betelgeuse is listed as a semiregular variable stars with variations occurring roughly every 400 days and 2,100 days.  Betelgeuse’s apparent magnitude can vary from 0.0 to 1.3.

Use the map linked below to help identify Betelgeuse.

Also if you would like to learn more about this amazing star follow this link.

The object for the week of January 17 is the open star cluster Collinder 70 or what is known as Orion’s Belt.  This group of three bright stars is one of the best known patterns in our winter sky.  It was recognized and used by many cultures including but not limited to the Sumerians, Greeks, Egyptians and Norse.  I  It can help you find the brightest star Sirius, the North Star, a number of constellations and many other targets.  As famous as Orion’s Belt is it is often overlooked that it is a star cluster.

To the unaided eye Orion’s Belt looks to be three bright stars.  If you were to look at it through any binocular you would quickly discover that it has a number of other stars clustered around it.  Star clusters come in two varieties; globular star clusters are ancient groups of tens of thousands of star that orbit the Milky Way.  Open star clusters are groups of tens to a few thousands of stars which are typically young and the clusters are scattered throughout the Milky Way.  Orion’s Belt is of the latter variety being an open star cluster which contains a bit over 100 stars.  The members of this cluster are about 8 million years old and are estimated to be 800 to 1000 light years away.

For more information use the following links bellow

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.