This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, February 25, 2022.

Information updated weekly or as needed.

Times given as local St. Louis time which is Central Standard Time (CST). 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 when CST.

Public Telescope Viewings

With the changing recommendations from the CDC regarding COVID-19, conversations regarding the return of star parties at the Saint Louis Science Center have begun. We are close to bringing back our public telescope viewings, but a few details still need to be worked out. We will post future updates as we learn more about when we can bring back telescope viewings.

Observing Highlight of the Week

The Big Dipper seen rising in the northeast at 7:30 p.m. Image created using Stellarium. 

If you look northeast this week around 7:30 p.m., you will find a familiar pattern of seven or eight bright stars. If you play connect-the-dots, these stars look like a scoop with a long handle or what some may call a dipper. As you might expect this pattern of stars is the Big Dipper which is best known for helping us find the North Star. It is also an excellent indicator of the seasons.

It may come as a surprise that the Big Dipper is not a constellation. For a long time, constellations were seen as a shape created by bright star patterns. This informal definition became problematic by the early 20th century due to the volume of objects being discovered. In 1928, the IAU formally adopted a list of 88 constellations of which each represented a section of the celestial sphere. Constellations are defined by arcs of right ascension and declination leading to a more efficient way to organize the sky. These 88 official constellations were first published in 1930 and they are still what is used today. It is important to note, people around the world developed their own culturally unique constellations. All of them are worth exploring, but it is useful to have one universal list to work from.

The star patterns not on the IAU list of 88 constellations are called asterisms. The Big Dipper is part of the constellation Ursa Major, but it remains one of the best-known star patterns in the northern hemisphere. The Dipper’s handle is seen as the bear’s tail and the bowl is the back of the bear. Early I described the Big Dipper as seven or eight bright stars. I gave two numbers because some viewers may see two stars where the Big Dipper’s handle bends. The two stars in question are Mizar and Alcor. Often called the Horse and Rider, this pair of stars was used by the Romans as an eye test. It appears the two stars orbit one another making them a binary system. Those with telescopes might see that Mizar is not one but two stars as well. The secondary star is called Mizar B with the primary named Mizar A. It is also known that Mizar A and B along with Alcor are spectroscopic binaries. This means that what we can see as two stars is really a total of six.

The Big Dipper is best known as a guide for finding the North Star. The two stars at the end of the bowl are name Merak and Dubhe. If you follow a line extending from Merak to Dubhe, it points you to the current North Star, Polaris. In a similar fashion, other stars of the Big Dipper can help you find other points of interest. Follow the curve of the handle, and you will find a bright orange star called Arcturus. This is the brightest star in the constellation Boötes the Herdsman. If you continue to past Arcturus, you will find the star Spica in the zodiac constellation Virgo. These are two of the best-known star hops from the Big Dipper but there are many more.

Lastly, I mentioned the Big Dipper is an indicator for the seasons. The Big Dipper is part of the circumpolar sky. This means it never really sets below the horizon. That said, there are times you may not find the Big Dipper as it is skimming the northern horizon and is obscured by trees and buildings. As the seasons change, the Big Dipper will be visible at varying times. If you pick the same time each season to look, then the Big Dipper’s position will vary. Say you choose to look for the Big Dipper after sunset. This time of year, it will be found in the northeast. Looking in late spring and early summer, it will be found overhead in the north.

Peek outside this week and see if you can find the Big Dipper. Around 7:30 p.m. it will be in the northeast. As the night continues, see if you can find it at different times. There are many reasons to spot this asterism of which we only scratched the surface.

The Sun and Moon


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

Sunrise is at 6:38 a.m. on Friday, February 25 and sunset is at 5:50 p.m. providing us with a bit over 11 hours of daylight. Even after sunset, the light from the Sun will dimly illuminate our sky for roughly 1 hour and 30 minutes. This period is called twilight, which ends around 7:18 p.m. this week. For those with a sundial, local noon occurs around 12:13 a.m. this week.

DaySunriseSunset
2022-02-25 6:38 a.m.5:50 p.m.
2022-02-26 6:37 a.m.5:51 p.m.
2022-02-27 6:36 a.m.5:52 p.m.
2022-02-28 6:34 a.m.5:53 p.m.
2022-03-01 6:33 a.m.5:54 p.m.
2022-03-02 6:31 a.m.5:55 p.m.
2022-03-03 6:30 a.m.5:56 p.m.
2022-03-04 6:28 a.m.5:57 p.m.
2022-03-05 6:27 a.m.5:58 p.m.

Moon 

Moonrise for Friday, February 25 occurred at 2:52 a.m. and moonset will occur at 12:09 p.m. On Friday, February 25 the Moon will exhibit a waning crescent phase with 27% of the lunar disk illuminated. New moon occurs on March 2, 2022, at 11:35 a.m.

International Space Station (ISS) Observing

Credit: NASA

Visible passes of ISS from St. Louis for the week of February 25 occur during morning hours. The best pass this week occurs on March 4. Use the table below for information about this and other visible passes this week.

Catch ISS from St. Louis starting Friday, February 25

DateStartsMax. altitudeEnds
TimeAlt.Az.TimeAlt.Az.TimeAlt.Az.
26 Feb-1.3 05:29:0711NNW 05:30:0312NNW 05:31:1710N
27 Feb-1 04:42:4012N 04:42:4012N 04:43:2210NNE
04 Mar-1.1 05:30:1410NNW 05:31:5113NNE 05:33:2910NE

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 Visible Planets

Looking southeast, at 6:00 a.m. February 26, 2022. Credit: Stellarium, EG 

The Moon, Mars and Venus seen at 6:00 am in the southeast on February 27, 2022. Sky image was created using Stellarium. Simulated phase images created using NASA Solar System Simulator v4.0.

This week, two naked eye planets are visible. Venus and Mars are both seen in the southeast before sunrise.

Venus

Venus has started a morning apparition and will be seen in the southeast before sunrise. Venus rises at 4:11 a.m. and should be easy to spot in the southeast by 5:00 a.m. This morning apparition lasts until the third week of October 2022. Venus reaches superior conjunction on October 22, 2022.

Mars

A new apparition for Mars has begun. Mars rises at 4:37 a.m. Start looking for Mars around 5:30a.m. as it clears trees and buildings. Mars will continue to climb out of the Sun’s glare as it heads towards opposition later this year on December 7, 2022.

James S. McDonnell Planetarium

Night Sky Update: February 25 – March 5, 2022