This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, March 5, 2021.

Information updated weekly or as needed.

Times given as local St. Louis time which is Central Standard Time (CST) until March 14 when we switch to Daylight Saving Time (CDT). For definitions of terminology used in the night sky update, click the highlighted text. If relying on times posted in Universal Time (UT), St. louis is -6 hours from UT when CST and -5 hours when CDT.

Public Telescope Viewings

Star parties at the Saint Louis Science Center have temporarily been canceled due to recommendations from the CDC regarding COVID-19. All public telescope events are canceled until further notice. As conditions change, we will reevaluate and update this article once public observing events resume.

Observing Highlight of the Week

View of the Constellation Cancer the Crab Looking East at 7:00 pm.
Credit: Stellarium, EG

The highlight for this week is the constellation Cancer the Crab. This is one of the 12/13 zodiac constellations that the Sun, Moon and planets appear in. The Moon will next move through Cancer on March 23 and 24 as it exhibits a waxing gibbous phase. Cancer is one of the tougher constellations to see owing to its faint stars. That said Cancer is easy to find being located between the constellations Gemini and Leo.

Cancer’s brightest stars range from 3.5 to 5.1 magnitude which will make them hard to see in a light polluted sky. The easiest way to find Cancer will be to look for the constellation Leo. Leo has a bright backwards question mark shape of stars that mark his head. This is found just south of the Big Dipper’s bowl. About 27° east of the head of Leo are two bright stars named Castor and Pollux. These are the twins of Gemini. Caner is found between Leo and Gemini.

One of the gems in this small constellation is the open star cluster Messier 44 (M44). At 577 light years, it is one of the nearest open star clusters. M44 is expected to contain 1000 stars of which about 200 are visible through large telescopes. Personally, I prefer to observe M44 through binoculars or a fast telescope at low magnification. The reason is M44 covers about 95 arc minutes of sky. Binoculars or low power views of M44 allow you to see more of the star cluster.

Under dark conditions, M44 is visible to the unaided eye appearing as a faint nebulous patch. This object was known to ancient astronomers. Aratus mentions M44 in a poem that dates to 260 BCE. The ancient Greek and Roman name for the star cluster was Praesepe which means manger. Along with their manger, there are two bright stars named Asellus Borealis and Asellus Australis which were seen as the northern and southern donkeys feeding at the manger.

To find Cancer this week go outside around 7:00 p.m. and look to the east. You will find Gemini overhead and Leo rising in the east. Cancer is not the largest or brightest of constellations, however it has several points of interest that make it worth tracking down.

The Sun and Moon

The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA

Sunrise is at 6:27 a.m. on Friday, March 5 and sunset is at 5:59 p.m. providing us roughly 11.5 hours of daylight. Even after sunset, the light from the Sun will dimly illuminate our sky for about 1 hour and 30 minutes. This period is called twilight, which ends around 7:27 p.m. this week. For those with a sundial, local noon occurs around 12:13 p.m. this week.

2021-03-05 6:27 a.m.5:59 p.m.
2021-03-06 6:26 a.m.6:00 p.m.
2021-03-07 6:24 a.m.6:01 p.m.
2021-03-08 6:23 a.m.6:02 p.m.
2021-03-09 6:21 a.m.6:03 p.m.
2021-03-10 6:20 a.m.6:04 p.m.
2021-03-116:18 a.m.6:05 p.m.
2021-03-12 6:17 a.m.6:06 p.m.
2021-03-13 6:15 a.m.6:07 p.m.


Moonrise for Friday, March 5 occurs at 12:28 a.m. and moonset will occur at 10:27 a.m. On Friday, March 5 the Moon will exhibit last quarter phase with 50% of the lunar disk illuminated. Last Quarter moon occurs at 7:30 p.m. on March 5.

International Space Station (ISS) Observing

Credit: NASA

Visible passes of ISS from St. Louis for the week of March 5 occur during morning hours. The best passes this week occur on the mornings of March 9 and 12. Use the table below for information about these and other visible passes this week.

Catch ISS from St. Louis starting Friday, March 5

Date Starts  Max. altitude  Ends  
07 Mar-1.9 05:45:0510NNW 05:48:0228NNE 05:50:5910E
08 Mar-1.4 04:58:0111NNW 05:00:2420NNE 05:02:5710ENE
09 Mar-1.1 04:12:3315NNE 04:12:4215NNE 04:14:4510ENE
09 Mar-3.6 05:46:3710NW 05:49:5974NE 05:53:2010SE
10 Mar-2.7 05:00:0917NNW 05:02:2743NNE 05:05:4010ESE
11 Mar-1.9 04:14:5528NNE 04:14:5528NNE 04:17:4810E
11 Mar-2.9 05:48:3610WNW 05:51:4033SW 05:54:4310SSE
12 Mar-3.8 05:02:5030WNW 05:04:1461SW 05:07:3210SE
13 Mar-2.4 04:17:5737ESE 04:17:5737ESE 04:20:0610SE

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 Visible Planets

Looking Southwest, at 7:00 pm, March 5, 2021
Credit: Stellarium, EG, 

Looking East Southeast, at 5:45 am, March 6, 2021
Credit: Stellarium, EG 

This week, four naked eye planets are visible. Mars is found high in the west after sunset. Jupiter, Mercury and Saturn can be found in the east southeast before sunrise.


Mercury is currently exhibiting a morning apparition with maximum elongation occurring on March 6. As we approach this date Mercury will be seen higher above the horizon each day before sunrise. Unfortunately, due to the angle of the ecliptic, this is not a great apparition for Mercury. The best chance to find Mercury will be to go out about 40 minutes before sunrise and look east southeast.


Currently Mars appears as a 1.0-magnitude object that will be visible high in the south about 30 minutes after sunset. Mars sets by 12:14 a.m. The observing season for this apparition ends around March 10, 2021 and superior conjunction occurs on October 7, 2021.


Jupiter is starting to climb out of the Sun’s glare just before sunrise. For your best chance to see Jupiter, look east southeast 40 minutes before sunrise. 


Saturn has returned to our morning sky. Look east southeast 40 minutes before sunrise to find the ringed planet.

Mars Perseverance Rover Update

After a successful landing on Mars, NASA’s newest rover Perseverance continues to go through testing before it starts its mission. Each week this section will contain a few of the images sent back to Earth as Perseverance explores Jezero crater. If you have not seen it yet, the first thing I would recommend watching is a video NASA released last week of the rover’s landing. Additionally, the rover has released a few panoramic views from its landing site that you will be better off going to NASA’s website to see. The video and panoramic images can be found at here.

NASA’s Mars Exploration Program website will be a good resource to visit each day to find any updates on the rover and its mission. Aside from information about Perseverance, NASA’s website will keep you up to date on any new findings from other Mars missions and research.

Mastcam-Z Image Showing First Target for the SuperCam Instrument
Credit: NASA/JPL-Caltech/ASU/MSSS

Perseverance View of the Delta in Jezero Crater
Credit: NASA/JPL-Caltech/ASU/MSSS

James S. McDonnell Planetarium

Night Sky Update: March 5-March 13, 2021