2022, February 24: Stellar Properties, Morning Planets, Moon


February 24, 2022: Venus, Mars and the moon are in the morning sky.  A stellar sample of stars is visible in the southern sky after sunset.

Chart Caption – Winter’s stellar sampler is in the south during the early evening hours of February.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:33 a.m. CST; Sunset, 5:35 p.m. CST.  Check local sources for sunrise and sunset times for your location.

The bright stars of the winter season at the mid-northern latitudes gleam from the southern sky during the early evening.  The sky is a representative sample of the types of stars that have been studied and cataloged.

In astronomy, star color (planets are not included) indicates temperature.

Over a century ago, Henry Norris Russell and Ejnar Hertzsprung, along with their observing groups, determined fundamental stellar properties.  These groups developed a classification system for stars through the chemical analysis of the spectra of stars (Annie Jump Cannon) and the relationship between the average stellar brightness and length of time it takes for variable stars to go through a period of brightness change (Henrietta Levitt).

Chart Caption – The Hertzsprung-Russel Diagram is a chart to compare stellar properties. (Credit: European Space Agency)

One resulting achievement of the research is a chart known as the Hertzsprung – Russell Diagram (H-R diagram).  The x and y axes are labeled with interchangeable terms.  Luminosity and absolute magnitude appear on the y-axis, while color, temperature, wavelength, or spectral class may be displayed on the x-axis.

The spectral class refers to the chemistry of the star and uses the letters O, B, A, F, G, K, and M, from hottest to coolest, blue to red. (Type O stars are hottest and appear bluish in color, while type M stars are “coolest” and are reddish.)

When the sun’s characteristics are plotted on the chart, it is not as bright as the named stars in the sky, but it is brighter than most of the dim stars that are near our solar system.  Astronomers sometimes refer to our central star as a “typical star” or “garden variety star,” because many other stars are like it.  It seems average compared to other stars.

Stars are neither sapphire blue nor ruby red.  Notice the subtle colors on the star chart at the top of this article.  The colors of the stars’ names have been set to the approximate color our eyes perceive.

Take a binocular or small telescope outside to view winter’s Hertzsprung-Russell collection of stars. Some optical aid amplifies a star’s brightness as well as its subtle color.  Here’s our tour of the winter stellar sampler.  Use the chart above.

  • Spectral Class O: Alnitak – the eastern star in Orion’s belt, Zeta Orionis (ζ Ori, m = 1.7), 815 light years distant (l.y.);
  • B: Rigel, Beta Orionis (β Ori, m = 0.2), 860 l.y.
  • A: Sirius, Alpha Canis Majoris, (α CMa, m = −1.5), 9 l.y.
  • F: Procyon, Alpha Canis Minoris (α CMi, m = 0.4), 11 l.y.
  • G: Capella, Alpha Aurigae (α Aur, m = 0.1), 40 l.y.
  • K: Aldebaran, Alpha Tauri (α Tau, m = 0.8), 70 l.y.
  • M: Betelgeuse, Alpha Orionis (α Ori, m = 0.4), 500 l.y. 

As you observe the stars beginning with the O spectral class, which spectral classes show a distinct difference of color? 

Morning Sky


Chart Caption – 2022, February 24: Venus and Mars are in the southeast before sunup.

Brilliant Venus is in the southeast before sunrise.  The planet rises nearly two hours, 30 minutes before sunup.  The planet outshines all other “stars” in the night sky. Through a spotting scope or small telescope, the planet shows a morning crescent phase that is 35% illuminated.

Dimmer Mars is 5.5° to the lower right of the brilliant planet.

Both planets are moving eastward in front of the stars of Sagittarius. Mars moves into Capricornus on March 6, followed by Venus the next morning.

These morning planets are racing eastward along the ecliptic.  Venus is picking up speed after its retrograde ended nearly a month ago.

Venus passes Mars for the final conjunction of a triple conjunction series on March 6.

Chart Caption – 2022, February 24: The moon is to the upper left of Antares, the heart of the scorpion before sunrise.

At this hour, the thick crescent moon – 44% illuminated – is about one-third of the way up in the southern sky, 3.9° to the upper left of Antares – “the rival of Mars.”

On celestial artwork, Antares marks the heart of the Scorpion.  The star Al Niyat, sometimes known as “the artery,” is to Antares upper right.

A globular star cluster, known as Messier 4 (M4 on the chart), is in the same binocular field as the moon and Antares this morning. 

Antares is an M spectral class star, like Betelgeuse.  Notice its reddish color with the binocular.

Photo Caption – Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all. (NASA/ESA Photo)

The cluster appears as a “pile of stars” against the sky.  Such clusters have been used to map the center of the galaxy and the sun’s location.  As the moon moves away from this region, look again on the next clear morning to see Antares and the cluster against a slightly darker sky.

Scorpius is one of the constellations that resembles its namesake, a scorpion.  The head is marked by three stars to the upper right of Antares. Two are Graffias – “the crab” – and Dscubba – “the forehead.”

The body of the scorpion curves toward the horizon and points back up into the sky with two stars at its stinger – Lesath, “the scorpion’s sting,” and Shuala, “the cocked-up part of the scorpion’s tail.”

Three planets are in transition in the sun’s bright glare.  Mercury was easily visible earlier in the month.  The speedy planet rises sixty minutes before sunup, and it is below the horizon during mid-twilight.

Saturn is slowly crawling into the morning sky.  It passed its solar conjunction over three weeks ago, rising thirty-nine minutes before the sun this morning.  It begins to appear low in the southeastern sky before sunup next month.

Jupiter is slowly departing the evening sky.  This evening it sets thirty minutes after sundown.

This summer, all five of the bright planets and the moon are in the morning sky before sunrise.  The same occurs in the evening sky as the year closes.

Tomorrow, the waning crescent moon is close to Venus and Mars.



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