THE SOUTHWORTH PLANETARIUM

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2021-2022: LXXXVII "It is clear to everyone that astronomy at all events compels the soul to look upwards, and draws it from the things of this world to the other." -Plato

THE DAILY ASTRONOMER

Monday, March 7, 2022

March 2022 Night Sky Calendar Part II

FRIDAY, MARCH 18: FULL MOON

Heavens, the many names that have been conferred onto winter's last full moon. The "worm moon," in reference to the creepy crawlers burrowing their way out of the thawing soil. The "sap moon," alluding to the seasonal flow of tree fluid or also to those of us naive enough to expect spring-like weather soon. Other seasonal full moon sobriquets include "the death moon, " (ho ho ho), "Chaste moon," (I don't want to know) or the "Vernal equinox moon," which, of course, makes no sense at all.

SUNDAY, MARCH 20: VENUS AT GREATEST WESTERN ELONGATION (47 degrees from the Sun)

Greatest elongation marks the time when an inferior planet appears as far from the Sun as possible in our sky. A planet appears in the eastern pre-dawn sky at greatest western elongation and in the western evening sky at greatest eastern elongation. This is definitely the best month of the year to see Venus (See Planet Watch)

SUNDAY, MARCH 20: VERNAL EQUINOX!! (GOLD EVENT!!!)

5:37 a.m.

SPRING IS BORN!!

The infant spring will soon wail, run, and keep us awake with its incessant noise making, while old man winter will be interred in a neglected grave, much to our unbounded delight. Astronomically, the ascending Sun intersects the celestial equator today. Throughout the year, the Sun appears to move along an undulating curve that alternately descends below and then ascends above the celestial equator, the projection of Earth's equator onto the sky.

To understand why the Sun appears to vacillate between a high and low point during the year, we need to view our planet from a position outside its orbit. Earth's axis is tilted relative to the vertical by 23.5 degrees. (See graphic below.) As the planet revolves around the Sun, the orientation of the Sun relative to the north and south poles is constantly changing. When Earth reaches the Summer (June) solstice, the north pole is aligned as close to the Sun as possible. Consequently, the Sun's altitude above the southern horizon is highest. Six months later, the North Pole is aligned away from the Sun as much as possible and the Sun's altitude is lowest. Conversely, in June, the south pole is pointed away from the Sun and in December, the south pole is aligned close to the Sun.

The revolving Earth. If Earth were not tilted on its axis, the Sun's altitude wouldn't change throughout the year. However, Earth's axis is tilted relative to the vertical by 23.5 degrees. As Earth revolves around its parent star., its poles shift alignments relative to the Sun. In the winter, the northern hemisphere points away from the Sun and in the summer, the northern hemisphere is directed toward the Sun. On both the vernal and autumnal equinoxes, neither pole is aligned toward the Sun, which shines directly on the equator. Image: National Weather Service

On the equinoxes, neither pole is aligned toward the Sun, which appears to shine directly on the equator. This date is called the equinox, from the Latin term "aequinoctium," meaning "equal night." Because Earth is neither uniformly dense nor perfectly spherical, the Sun doesn't fall on the planet evenly and we will not have twelve hours of daylight on the equinox.

MONDAY, MARCH 21: VENUS AT DICHOTOMY

Venus at what?

Venus at dichotomy: half lit, half dark from our perspective. Or, if you prefer, a quarter Venus. Like all bodies in orbit around the Sun, Venus is always half illuminated. However, we rarely ever see a half-lit Venus because its orientation relative to Earth always changes. Look through a telescope or binoculars at Venus today and you will see Venus as "D " shaped.

FRIDAY, MARCH 25: LAST QUARTER MOON

MONDAY, MARCH 28: VENUS, MARS AND SATURN WITHIN A CIRCLE 5.3 DEGREES IN DIAMETER (SILVER EVENT!!)

As we'll learn in the "Planet Watch" section, one will have to look into the pre-dawn eastern sky to find planets this month. This morning one will see Venus, Mars and Saturn "clustered" together. A beautiful sight for those who love to observe planets.

WEDNESDAY, MARCH 30: MOON NEAR JUPITER One could almost consider this event to be "academic." Academic events are either not visible or scarcely visible. One will see the waning crescent moon (1% illuminated) close to Jupiter very low along the eastern horizon. An observer MIGHT see these two bodies this morning just before the brightening twilight obscures them, but they'll both be difficult to see. Good luck!

PLANET WATCH

A prefatory note: All the visible planets are currently congregating in the early morning eastern sky.

MERCURY
Host constellations: Early month - Capricornus; Mid month - Aquarius; Late month - Pisces, then Cetus

By virtue of its proximity to the Sun, Mercury always remains close to it in our sky. This month, Mercury inches closer to the Sun in the eastern pre-dawn sky. This fleet-footed planet flits swiftly between the morning and evening skies. For most of the month, it remains in the early morning sky. By the last week of March, however, it vanishes and will emerge in the evening sky next month. VERDICT: Mercury watchers are accustomed to frustration. However, to minimize that frustration, seek it out early this month.

WAIT A MINUTE!! How can Mercury appear in the constellation Cetus?! Cetus is not part of the zodiac!

Oh, I was wondering if you'd notice that. We know that the Sun can only pass through the thirteen constellations comprising the Zodiac: Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Ophiuchus, Sagittarius, Capricornus and Aquarius. However, the planets, though confined to a band centered on the zodiac, are not quite as constrained. Planets can veer slightly away from the zodiac into adjacent constellations. In theory, according to Belgian astronomer Jean Meeus*, planets can occupy 24 constellations. Of course, most of the time, one will find them in the zodiac patterns.

VENUS: PICK PLANET! Host constellation Sagittarius - month's beginning; Capricornus - starting from the month's second week

A gorgeous sight for early risers! This Dantean sphere of flame and tumult dazzles and delights in the eastern pre-dawn sky. Although Venus' brightness dims slightly throughout the month (magnitude -4.4 on March 1; -4.2 on the 31st), it remains an eye-pleasing spectacle for those intrepid enough to venture outside before Sunrise. VERDICT: Who needs a warm bed when you can stand before a pre-dawn goddess?

MARS

Host constellation Sagittarius - month's beginning; Capricornus - starting from the month's second week

One must feel an immense amount of sympathy for Mars: the dim, awkward older brother standing in the shadow of its brilliant and beguilingly beautiful sister Venus. While Venus mesmerises the masses, Mars merely exudes a moderately bright glow that commands scant attention. Of course, through the month Mars brightens as it continues to draw closer to Earth. (Magnitude 1.4 on March 1st; 1.1 on March 31st.) Despite this brightening, Mars will appear about 130 times dimmer than Venus. VERDICT: Be a balm to Martian feelings and give it a glance or two in those moments when Venus' allure might wane.

JUPITER

Host constellation: Aquarius

Well, what can one say? After having served so dutifully as our evening sky beacon, the giant Jovian has snuck behind the Sun for a well-deserved hiatus. This bloated behemoth will insinuate itself into the pre-dawn eastern sky toward month's end, but remain exceedingly difficult to see. VERDICT: Breathe. Be one with Jupiter's absence. If you must behold the behemoth, you might snatch a glimpse in the pre-dawn by month's end. Otherwise, wait until April when Jupiter joins the morning sky throng of planets.

SATURN

Host constellation: Capricornus

As you can probably guess, Saturn is also to be found in the early morning sky. Though dimmer than Mercury and Venus, it shines a bit brighter than Mars. The Ring Lord world tends to shine less brilliantly than the other because of its distance. In fact, the mean distance separating Saturn and Jupiter is about equal to the distance separating Jupiter from the Sun. The gas giants have certainly been allotted ample amounts of space. VERDICT: Seek out Saturn while you're admiring Venus, pretending to care about Mars and trying to locate Mercury.

*Not to be confused with the Belgian ice hockey player of the same name.

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