Archive for month: March, 2021

Highlights:  Comet Journal, Martian Landers, Meteor Showers, Spring Equinox, Planet Plotting, March Moon

Focus Constellations:  Ursa Major, Ursa Minor, Draco, Cepheus, Cassiopeia, Camelopardalis, Perseus, Auriga, Taurus, Orion, Monoceras, Gemini, Cancer, Leo, Coma Berenices, Bootes

• Comet Journals

Comet C/2020 R4 (ATLAS) is a long period comet from the Oort Belt. It is at 9th magnitude between Aquarius and Aquila and will reach perihelion on March 1. The comet will get progressively brighter as it moves, in April, from east to west in northern skies in Hercules and Bootes and is closest to Earth on April 23 when it may reach between 7th and 9th magnitude. It will dim rapidly in May as it appears to head toward Leo.

No other March comets exceed 12th magnitude in brightness nor are any currently visible comets likely to achieve better than 12th magnitude this year.

• Mars Landers

NASA ignored the valuable techniques revealed by the Forbidden Planet, When Worlds Collide, Star Trek, and Star Wars movies with the 21st Century landings on Mars of Spirit and Opportunity in 2004, the Curiosity Science Laboratory in 2012, the Insight Lander in 2018, and Perseverance in Jezero Crater last month. 

Spirit & Opportunity entered the Martian atmosphere inside of heat shielded capsules that descended as they were slowed by atmospheric friction until it was safe to unfurl their parachutes. The capsules then opened, suspended the landers protected by airbags, and fired its retrorockets to further slow descent until it was safe to release the landers which bounced at least a dozen times before rolling to stops. Due to its weight, Curiosity required a more sophisticated process. After the capsule slowed, it unfurled its parachute, opened and released a “sky crane” which fired retrorockets to halt the descent, then lowered the suspended rover to the ground. The lighter weight Insight lander had its own retrorockets, which enabled it to land after the capsule heat shield and parachute had done their work. Perseverance is heavier so mission scientists relied on the process that safely landed Curiosity and, for good measure, included an array of cameras to display each step for all of us to see. 

InSight’s heat flow measurement experiment was abandoned in January, but seismic and weather observations proceed apace. Scientists analyzed seismic data and suggest that the flurry of marsquake activity last summer, its subsequent reduction, and recent resumption may be due to wind masking lower amplitude seismic waves during the windy season. They also discovered that, like our Moon, quakes on Mars display an absence of surface seismic waves accompanying the seismic body waves. A highly fractured outer ten kilometers of the planet’s crust like that attributed to our Moon may be the cause. Fractures scatter and absorb seismic waves. 

From mid-January to present, Curiosity climbed up through a rubbly bedrock area in the upper layers of the water deposited, clay bearing, 300 foot thick Murray formation, reaching its top where it transitions to the overlying layered sulfate bearing unit which was first identified with spectrometers from orbit. Following departure from the crater floor in 2014, the rover ascended the Murray formation. As it climbs through the transition zone and above Curiosity opens a new chapter. The transition zone has a lower clay bearing unit like the Murray formation and the upper part is composed of sulfate bearing clay minerals. Although Curiosity has not crossed its boundary, long range views of the lower part of the layered sulfate unit appear to show fine sandstone with cross-bedding indicative of wind blown deposition, features visible in the upper part suggest water current deposition.

• Meteor Showers

The 2 meteor showers in March are both rather minor and one is confined to the southern hemisphere. The Virginids are in northern skies and are best viewed around the 14th. They only produce about 5 meteors an hour in dark skies without light pollution.

Early March – Early April: Virginids. Active Jan 25-Apr 15. Radiant 13h00m -04°, ZHR 5. 30km/sec. Waning Gibbous Moon. Progenitor: potentially hazardous near-Earth asteroid 2007CA19 

March 13: Gamma Normids. Active Feb 25-Mar 22, Radiant 16h36m -51°, ZHR 8?, 56 km/sec. Waxing Crescent Moon. Progenitor: unknown 

• Spring Equinox

At 5:40AM EDT on March 20, the Spring (Vernal) Equinox marks the beginning of Spring when the Sun will be above Earth’s equator and will appear to move into the northern hemisphere skies during the following days. Earth will be positioned so that our axis of rotation will be leaning away from our orbiting direction and will be perpendicular to a line between the Earth and Sun. In this orientation, all locations on Earth receive 12 hours of daylight and 12 hours of darkness.

• Planet Plotting 

Mercury (+0.3 to +0.4) in Capricornus and Aquarius, Venus (-3.8) in Aquarius and Pisces, and Jupiter (-1.8)

Saturn (+0.7 to +0.8) in Capricornus are morning planets in March. All appear fairly close to one another and to the Sun. Mercury is at maximum western elongation from the Sun on the 6th, and Venus’ superior conjunction with the Sun is on the 26th. Saturn appears farthest from the Sun, rising 2 hours before sunrise. Mercury and Jupiter are next, rising about an hour and a half before the Sun. Venus rises about 15 minutes before sunrise and, after its conjunction with the Sun on March 10, Neptune (+8.0) in Aquarius moves to the morning sky, rising before the Sun for the rest of the month. On the  5th, Mercury and Jupiter are less than a degree apart, and Venus and Neptune follow suit on the 14th. Mercury and Neptune are slightly more than a degree apart on the 30th. 

Mars (+0.9 to +1.3) and Uranus (+5.8 to +5.9) grace the southern evening skies in Taurus and Aries respectively. They appear after sunset and set about midnight. Mars is over three times farther away than it was at opposition last autumn and is drastically dimmer. Even so, it is still at first magnitude and makes a nice pairing with the Pleiades star cluster which is 2.6° NNW of the red planet on Mar. 5.

Planet	Constellation(s)	Magnitude	Planet Passages	Time	Date
Sun	Aquarius, Pisces	-26.8	New Moon	5:22AM EST	3/13
Mercury	Capricornus, Aquarius	+0.3 to -0.4	Jupiter, 0.32°N	2:00AM EST	3/5
Mercury	Capricornus, Aquarius	+0.3 to -0.4	Max. West Elongation	6:00AM EST	3/6
Mercury	Capricornus, Aquarius	+0.3 to -0.4	Neptune, 1.3°NW	12:00AM EDT	3/30
Venus	Aquarius, Pisces	-3.8	Neptune, 0.37°NW	1:00AM EDT	3/14
Venus	Aquarius, Pisces	-3.8	Superior Conjunction	2:00AM EDT	3/26
Mars	Taurus	+0.9 to +1.3
Jupiter	Capricornus	-1.8 to -1.9	Mercury, 0.32°N	2:00AM EST	3/5
Saturn	Capricornus	+0.7 to +0.8
Uranus	Aries	+5.8 to +5.9
Neptune	Aquarius	+8.0	Solar Conjunction	7:00PM EST	3/10
Neptune	Aquarius	+8.0	Venus, 0.37°SE	1:00AM EDT	3/14
Neptune	Aquarius	+8.0	Mercury, 1.3°SE	12:00AM EDT	3/30

On the 9th, a waning crescent Moon is 3.6° from Saturn at 8:00PM EST, 3.9° from Jupiter at 1:00PM EST on the 10th, 3.5° from Mercury at 11:00PM EST, 3.6° from Venus at 11:00PM EST on the 12th, and 3.9° from Neptune at 2:00AM EST on the 13th. A waxing crescent is 2.5° from Uranus at 1:00AM EDT on the 17th, and 1.9° from Mars at 4:00PM EDT on the 19th.

• March Moon

The New Moon of March on the 13th at 5:22AM EST is the start of Lunation 1215 which ends 29.43 days later with the New Moon of April on the 11th at 10:32PM EDT. The Full Moon of March is on the 28th at 2:48PM EDT. It is commonly known as the “Sap, Crow, or Lenten” Moon. In colonial times, the March Moon was the “Fish Moon” and in Medieval England, it was the “Chaste Moon.” Celts named it the Moon of “Wind or Seed” and the Chinese call it“ Sleepy Moon”.  Anishinaabe (Odawa and Ojibwe) people recognize it as “Onaabani-giizis” (Snowcrust Moon).

At Lunar Perigee, on the 2nd at 12:17AM EST, the Moon is 229551 miles from Earth (57.92 Earth radii). At apogee (maximum solar distance), on March 18 at 1:00AM EDT, the Moon is at 251824 miles (63.54 Earth radii). Another lunar perigee occurs on the 30th at 2:16AM EDT when the Moon is at 223884 miles (56.49 Earth radii).

Planet	Constellation	Magnitude	Moon Passages	Moon Phase	Moon Age
Sun	Pisces	-26.8	5:22AM EST, 3/13	New	0 Days
Mercury	Capricornus	0.1	3.5°SE, 11:00PM EST, 3/10	Waning Crescent	29.12 Days
Venus	Aquarius	-3.8	3.6°SE, 11:00PM EST, 3/12	Waning Crescent	28.75 Days
Mars	Taurus	1.2	1.9°SE, 4:00PM EDT, 3/19	Waxing Crescent	7.08 Days
Jupiter	Capricornus	-1.8	3.9°SE, 1:00PM EST. 3/10	Waning Crescent	28.79 Days
Saturn	Capricornus	0.76	3.6°SE, 8:00PM EST, 3/9	Waning Crescent	27.33 Days
Uranus	Aries	5.9	2.5°SE, 1:00AM EDT, 3/17	Waxing Crescent	5.79 Days
Neptune	Aquarius	8.0	3.9°SE, 2:00AM EST, 3/13	Waning Crescent	2.2 Days