The Moon, Mars, and NASA’s Perseverance

   Thursday evening February 18th the 7-day old almost first quarter but still waxing crescent Moon will be about 3o from the ‘Red Planet’ Mars. Despite the -11.75 apparent magnitude of the Moon Mars, with an apparent magnitude of 0.75, will still be visible.

   
   NASA Perseverance is scheduled to land on Mars on 18 February 2021, at around 20 UT or 2 pm CST.

   
   
   
   
   
   
   
   

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Eppur Si Muove


   February 15th is Galileo Day.
   Quoting Galileo, “and yet it still moves”, in reference to the Earth actually orbiting the Sun. So how to acknowledge his achievements and contributions to modern Science? Read on…

   Jupiter’s Moons
   One enjoyable pasttime is to observe the constantly changing four largest moons orbiting Jupiter. Sometimes known as the Galilean Satellites, they are: Io, Europa, Ganymede, and Callisto. Named after Galileo who made many observations of the moons and from these observations and other observations led him to question the Geocentric model of the solar system. These four planet-sized moons are visible as small bright stars on either side of Jupiter and depending on the time and date of viewing their arrangement around Jupiter is never the same as this animated graphic, set to 1-Earth day intervals, is showing.
   Recreate Galileo’s observations of the Galilean satellites through the use of an online simulation, the Java applet, Juplet. Input dates or times to see the position of the four Galilean satellites.
The Juplet will display the planet and the satellite configuration for the date and time on the computer, or you could easily edit the date and time, and after pressing the Enter key see a different configuration. To keep track of these changes the position of each satellite relative to Jupiter could be drawn on a data table similar to Galileo’s data table.

   This video, ‘Orbs of Jupiter’, was one of the videos I made for a live musical performance at the Gottleib Planetarium at Science City in Kansas City MO. The original videos were made for full-dome projection – this one has been flattened. Music was written by Richard Johnson and performed by Rebecca Ashe (Flute) and Cheryl Melfi (Clarinet). Live and pre-recorded Electro-acoustical sampling by Richard Johnson and Daniel Eichenbaum. The soundtrack for the video is from the live performance by Dark Matter.

   
   
   

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Crescent Moon – Neptune Conjunction

   Saturday February 13th the 2-day old thin waxing crescent Moon will be about 2-3o from the outer planet Neptune and about 6-7o to the west from Dwarf Planet Ceres. The Moon will pass by Ceres over the next 24 hours and by about this time tomorrow the Moon will be to the east from Ceres.
   I should point out that Ceres with an apparent magnitude between 8th and 9th and Neptune with an apparent magnitude between 7th and 8th neither will be visible to the unaided eye.
   However when you are looking toward the Moon you will be looking in the direction of these two distant members of our solar system. This graphic shows the position of the Earth, our Moon, Ceres, and Neptune on February 13th. From this perspective objects to the left of the Sun will be seen in the evening skies as the Earth rotates.

   
   
   

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Imbolog 2021

   Watch That WoodChuck!
groundhog newspaper   On February 2, we watch for the groundhog to emerge for reasons that originate from ancient Celtic tradition. Groundhog Day was known as lmbolog, or sheep’s milk, a time for nurturing young sheep and planting spring crops. The belief arose that if lmbolog were to be sunny and clear, then winter’s effects would endure, foreshadowing a long winter. How­ever, if skies were overcast, then the warmer days of spring would arrive early. To farmers then and today, an early spring means early spring plant­ing and a subsequent early harvest. Often fires were lit to commemorate the event as fires were a sign of warmth and light, both of which increased as days lengthened.
not a meteorologist   German immigrant farmers are credited with bringing Groundhog Day with them to the United States as they settled in Pennsylvania. To them, February 2 was called Candlemas Day, because of the practice of lighting candles on this day in celebration of early planting. The Germans believed that the badger was able to predict the weather on the basis of whether or not its shadow appeared. If the badger, or groundhog, saw its shadow on Candlemas, it would be scared and return to its burrow for another six weeks to sleep through the long winter. However, if the skies were cloudy then no shadows would appear, and an early and warm spring would be expected. The importance of this day to German immigrants, and its impact on their farming gave rise to the couplet:
         A farmer would rather see his wife upon a bier,
         than that Candlemas Day should be sunny and clear.

puxs-phil-lied   Year after year, since 1898, crowds have gathered in Punxsutawney, Pennsylvania, on February 2 to wait for a certain groundhog to emerge from its burrow. Today the belief in this as a predictor of weather is not nearly as consequential as it appears despite all the hoopla created by the news media. Yet, there is some scientific rationale to this ritual, albeit not in the accuracy of the forecast. When the skies are clear, temperatures tend to be cold as the ground radiates heat absorbed during the day back into the atmosphere; and when skies are over­cast temperatures tend to moderate as clouds trap heat nearer the ground.
Midpoints
Groundhog-Standing2   To other cultures in the Northern Hemisphere Candlemas Day was celebrated as the midpoint, or cross­ quarter day, between the winter solstice and the spring equinox. Cross-quarter days occur midway between the astronomical events that mark the beginning of each of the four seasons, the solstices and the equinoxes. The second cross-quarter day of the year, as it is calculated mathematically, occurs on May 6, although it is often associated with May Day, on May 1. The third cross­ quarter day of the year is August 7, the only one of the four without a significant event associated with it. Mid-autumn, the fourth cross-quarter day, occurs on the last day of October, Hallowmas Eve, or as we now know it, Halloween.
   Interestingly this system of equinox, solstice, and cross-quarter days has led to some confusion as to when the seasonal midpoints and endpoints occur. For example, June 21-22 is the official date for the start of summer in the Northern Hemisphere, but it is sometimes referred to as midsummer’s day. This would suggest that summer actually begins on May Day and ends in early August. In a similar manner, December 21, the start of winter for the Northern Hemisphere, is some­times referred to as midwinter’s day. This would imply winter actually begins at the end of October, and concludes (assuming no shadow is seen) on Groundhog Day.
groundhog   So will we have a long winter, or will it be short, and our spring be an early spring? No one can predict this, at least not based on seeing one’s shadow. However, come this February 2, rest assured that crowds will once again gather to watch Punxsutawney Phil emerge from his hole.
   Adapted from “Watch that Woodchuck” Scope on the Skies. Science Scope Magazine. February 1993.

   
   
   

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Conjunction – Elongation – Conjunction

   Saturday evening watch for the 11-day old waxing gibbous Moon to be in conjunction with and about 3o from the reddish star Aldebaran in the constellation Taurus the Bull.

   Earlier in the evening the innermost planet Mercury was visible over the western horizon shortly after sunset. Mercury, on this date, will be at its Easternmost Elongation for this orbit. At elongation, eastern or western, Mercury, and also Venus, will be as far ‘out’ from the Sun to the right or left as we see the inner planets from Earth. At eastern elongation the inner planets follow the Sun across the sky during the day and appear as evening planets over the western horizon. At western elongation the inner planets ‘lead’ the Sun across the Sky during the day which means they rise ahead of the Sun and are seen as morning planets.

   But Wait – there’s still more!
   Saturn reaches solar conjunction on this date. During solar conjunction for an outer planet that outer planet will either be too close to the Sun to be seen or is on the opposite side of the Sun. When an outer planet reaches solar conjunction it moves from the evening skies to the morning skies.

   
   
   

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Earth at Perihelion – 2021

   Feel the Heat?
   As the Earth continues its annual trek around the Sun, Saturday January 2nd at 13 UT (7 am CST), the Earth reaches a point in its orbit that is called perihelion. Perihelion is the minimum distance that separates the Earth from the Sun, and we are the closest to the Sun for the year at this point in the orbit. So this year, 2021, the Earth is 0.9833 AU; 91,403,445 miles; 147,099,586 km from the Sun.

   Approximately one-half year or one-half revolution later, on July 5th, the Earth is at aphelion and is 1.0167 AU (94,508,169 miles; 152,096,155 km), its maximum distance from the Sun for 2020. This approximately 3% difference in distances between perihelion and aphelion is due to the shape of the Earth’s orbit being elliptical rather than circular. However the Earth has a mildly elliptically shaped orbit that is closer to being slightly out-of-round than the incorrect, very elliptical orbit that is often shown – like the illustration used here.

sun2014-ani   In Astronomy the shape of a planet’s orbit is called eccentricity, with 0 being a circle and 1 a straight line. Any value between 0 and 1 represents an ellipse. The shape of the Earth’s orbit is so close to being circular that the apparent size of the Sun does not appear to change as this animated graphic shows. The difference between perihelion and aphelion is about 3%.

   Eccentricity for each planet is listed below for comparison.

Planet	   Eccentricity	
Mercury	   0.2056
Venus	   0.0068
Earth	   0.0167
Mars	   0.0934
Jupiter	   0.0484
Saturn	   0.0542
Uranus	   0.0472
Neptune	   0.0086
Pluto	   0.2488

   To read more about the Earth’s orbit and get some teaching ideas click here to download a PDF copy of my January Scope on the Skies column Solar Explorations.


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Following the Arrows

   A few years ago one of my “Scope on the Skies” columns was about the Juno mission to Jupiter, but the focus was more or less about how the Juno spacecraft used solar power as far away as Jupiter, the Planetary Society and their Light Sail project, and a SciFi story by Isaac Asimov. However for me the most interesting part writing the column was learning about large concrete arrows scattered around our country. These turned out to be directional arrows used by pilots in the days of daytime flying and no radar for travel guidance. Arrows later had Beacons with lights, then radio signals were added. Eventually these were replaced with more advanced radios and radar.

   So we loaded the truck, gassed up, and drove from Lee’s Summit, MO southwest across Kansas to near the city of Haysville, KS to find the arrow near there. It was located along a dirt county road and nearly buried in grass and bushes. However the arrow was intact but whatever color it was painted had faded away.
      (37°32’04.7″N 97°25’11.9″W)

   Then we drove further south to near the Oklahoma, Kansas state line to the city of Anthony, KS. A couple of miles west from the city is the Anthony Airport and just off the road near the end of the runway is an Arrow and a Beacon.
      (37°09’06.8″N 98°04’37.0″W)

   Click here to download the ‘Scope’ column about the Arrows.

   
   
   
   
   
   


   
   
   

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July Moon at Descending Node

   Friday July 3rd the 11-day old waxing gibbous Moon crosses the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.

   On the date of the descending node the waxing gibbous Moon will be over the southern horizon around local time for sunset. Look for the Moon to be about 9-10o from the heart of Scorpius the Scorpion, the reddish star Antares.

   
   
   
   
   

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Thin Moon on the Move

   Sunday June 21st, on the other side of the Earth from the U.S.A., the new Moon will be passing between the Earth and the Sun giving that side of the world an annular solar eclipse.
   About 1/2-day later the just past new Moon, an 0.80-day young thin waxing crescent Moon may be seen just above the western horizon at sunset local time. If you see the Moon look closely for a star-like object just to the left from the Moon. This is the inner planet Mercury.
   If you miss the Moon and Mercury on Sunday evening wait until Monday evening June 22nd to see the still thin 1.85-days old waxing crescent Moon near one of the Gemini ‘Twin’ stars, Pollux.
   Not had enough? On Tuesday June 23rd the 2.80-days young waxing crescent Moon will be near M44, the Beehive Cluster.
   Any of these conjunctions will look great in binoculars.

   
   
   

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I Should’ve Gone to Mars!

   Let’s face it. I am a ‘closet geographer’! Can you say Geomorphology? That is my passion when not looking skyward. I am fascinated by landforms and how they came to looking the way they do now. What were the weathering and erosional process that were involved and how did the patterns of those process do what it did? And that leads into this blog, sort of a repeat of a previous blog about taking a road trip on Mars, and two more recent blogs about this trip. This time a road trip, or actually an air trip to my brother’s home in Sun City Arizona, a northwest suburb of Phoenix.
   So imagine the diverse landforms you could see along the way either from the ground in a car or by plane as I did traveling across the United States from my home in Lee’s Summit, Missouri to my brother’s place near Phoenix Arizona. From the wooded and hilly and green western Missouri southwest across the Great Plains of Kansas and Oklahoma to the Texas Panhandle where the terrain takes on a more brownish and rugged look. From the Panhandle the route takes you across New Mexico through Albuquerque then into eastern Arizona to Flagstaff and then south to Phoenix.

   So imagine using the same latitudes and longitudes on Earth, but this time put them on the surface of Mars. Assuming that something like this will become a reality in the future what types of terrain would you see along the way?
(Mars Geologic Map – source: USGS)

   
   
   

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