The Celestial Sphere

By Matthew Johnson

The long-awaited vernal or spring equinox occurs on March 19 at 11:06 p.m., when the sun is directly over the equator. On the equinox (from the Latin for “equal”), we have an almost equal 12 hours of daylight and 12 hours of nighttime, signifying the first day of spring in the Northern Hemisphere and of fall in the Southern Hemisphere. 

Once the Earth reaches the vernal equinox in its revolution about the sun, each day gains approximately three more minutes of daylight until the maximum amount of daylight on the summer solstice in June. 

Planets
Mercury is one the most challenging planets to observe, since it can only be seen just before sunrise or just after sunset. It is best viewed on March 24 looking to the west, about 30 to 40 minutes after sunset. It will be approximately 10 degrees above the western horizon, with Jupiter about 30 degrees to its upper left and Uranus about 3 degrees directly above Jupiter. Binoculars, a small telescope or a spotting scope are recommended. The horizon to the zenith is 90 degrees.

Venus will remain the brightest morning “star” all month long. (Venus is often referred to as the evening or morning star even though it is a planet.) On March 1, about a half hour before sunrise, Mars and Venus will be less than 5 degrees apart but very low in the eastern sky. Mars is quite distant now and may require binoculars to view. 

Jupiter is the gem in the sky this month. Look toward the west early in the the month just after sunset. With binoculars, a telescope or spotting scope one can observe Jupiter’s four Galilean moons as well as much of its atmosphere, especially the two brownish belts spanning the planet’s equator. The planet’s Great Red Spot also comes into view approximately every 10 hours. In 1610, Galileo Galilei was the first to view Jupiter’s four largest moons.

On March 21, Saturn can be viewed about 20 minutes before sunrise just below Venus. The two planets are so close together that they may appear to be a single bright object. Use binoculars to separate Saturn from the brilliant light of Venus. Additionally, Mars is to the upper right of the two planets on this morning. At 6:30 a.m. on March 29, Saturn will be approximately halfway between Venus below and a faint Mars above. 

Moon
March 3: Last quarter (left half of the moon illuminated).

March 10: New moon (no visible moon). The best time of the month to observe faint objects is in the days before and after the new moon because there is no moonlight to interfere.
March 17: First quarter (right half of moon illuminated).

March 25: Full moon. 

March’s full moon was historically known by Native American tribes as the Worm Moon, because earthworms and grubs tend to emerge from their winter dormancy at this time of year, attracting robins and marking a sign of spring. It is also referred to as the Sap Moon, since this is the time when the sugar maple trees begin to produce sap to be rendered into maple syrup and sugar candy.

Lunar Eclipse
During the full moon on Monday, March 25, a penumbral lunar eclipse will occur. The moon’s reflected sunlight will be slightly reduced during the eclipse because 95.57 percent of the moon will be immersed in Earth’s penumbral shadow.

During a penumbral eclipse, the moon passes through the outer part of Earth’s shadow (called the penumbra) created when Earth travels between the sun and the moon and blocks some of the sun’s light from falling on the moon’s surface. The moon’s disk will continue to be illuminated but to a slightly lesser degree. A penumbral eclipse of the moon is very subtle, only perceptible to those who have exceptional vision. 

The Sun 
The National Oceanographic and Atmospheric Administration (NOAA) says on its website that “Space Weather describes the variations in the space environment between the sun and Earth. In particular Space Weather describes the phenomena that impact systems and technologies in orbit and on Earth. Space weather can occur anywhere from the surface of the sun to the surface of Earth.” Examples of space weather are solar flares, Coronal Mass Ejections and geomagnetic storms. Different types of space weather affect different Earth technologies. 

Recently, there have been major solar flares and Coronal Mass Ejections (as I discussed in last month’s “The Celestial Sphere” column). Solar Cycle 25 is expected to create intense solar weather into 2025, with daily sunspot maximums reaching above 150. Monitoring and predicting solar events are extremely important. Even minor space weather has had major impacts on Earth and “near space.” In February 2022, after a successful Cape Canaveral launch, minor geomagnetic storming caused 38 of 49 SpaceX Starlink satellites to fail to achieve their final low earth orbit. On failing to reach orbit, these 38 satellites burned up during reentry into Earth’s atmosphere. 

Daylight savings time begins on March 10 at 2 a.m., so set your vintage and antique clocks and watches to 3 a.m., when we “spring” forward one hour. 

Solar Eclipse
A total solar eclipse is crossing the United States on April 8, about five weeks from now. Plane flights and rental cars are selling out quickly to destinations where “totality” is occurring.

Comet
A comet is approaching. Comet 12P/Pons-Brooks was first discovered by Jean-Louis Pons on July 12, 1812, and independently rediscovered by William Brooks in 1883. It returns about every 71.3 years, classifying it as a Halley-type periodic comet. The comet is possibly the parent body causing the K-Draconids meteor shower. It is expected to reach its maximum brightness in April. Its closest approach occurs just a few days before the total solar eclipse, and it is hoped that the comet will be bright enough to be viewed with the naked eye on April 8.

Additional information related to the celestial sphere, including dates and times for observations, can be found by searching the web under terms such as NASA & James Webb Telescope, NOAA & space weather, astronomy & Earth’s orbit.