Earth Hour 2021

   Saturday March 27th is the annual Earth Hour celebration. Started in 2007 the Earth Hour celebration is a world-wide citizen-powered effort to call attention to our planet’s environment and the need to better take care of our home (our only home).
   Earth Hour, although one hour, is an ongoing effort to encourage taking action about climate change as well as the destruction of nature and decreases in biodiversity.
   So on Saturday evening March 27th, at 8:30 pm (your local time), turn the electrically powered lights off in your house for one hour. But don’t stop there. Act locally and think globally! Get involved – stay involved.

   With lights out this may be a good time to step outside, weather permitting, and take a look at what could possibly be darker night skies with lights off in your neighborhood. Mars is visible high above the southern horizon near the stars of Taurus the Bull, however this year the light from the full Moon will brighten the skies.

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            Watch this short video story “There Once Was A Sky Full of Stars”.

   From the Earth Hour web site:

Our first-ever Earth Hour “Virtual Spotlight”
Over the years, the lights-off moment saw entire streets, buildings, landmarks, and city skylines go dark – an unmissable sight that drew public attention to nature loss and the climate crisis.
This year – amidst the current global circumstances – in addition to switching off your lights, we also invite you to raise awareness and create the same unmissable sight online, so that the world sees our planet, the issues we face, and our place within it, in a new light.

   That’s us, and we have a home that is danger from not only climate change, the destruction of nature, and decreases in biodiversity, but our only home is also losing to the demands of an increasing population and its effect on the local environment. At the 8 Billion Angels web site there is information about the effect a growing population is having on our planet. Be sure to watch the video trailer and perhaps consider organizing a community viewing.
click on graphic to go to the Earth Overshoot web site   Continue learning about our impact on the Earth by visiting the 8 Billion Angels companion web site Earth Overshoot.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Birds of Galveston Island

   I like to hike and especially the higher the hike (not me!) the happier I seem to be. Less O2, or something in the way I am wired! I don’t know, but this past week my wife and I were at sea-level while staying in Galveston, Texas. Thus giving me an opportunity for a level, no hill, hike along the shoreline and inland.
   Along the shoreline we encountered mostly Sea Gulls – curious how they stand on one leg.
   From studying the area before we went there allowed me to find Galveston State Park and a series of trails amongst the salt-marsh wetlands about 0.5 miles inland from the shoreline. The state park is a habitat for a variety of land and water animals, but early in the morning there seemed to be more birds than during an afternoon visit.
   Other than the day walking along the shoreline the rest of the days had skies that were mostly overcast with thin clouds giving the sky a whitish bland coloring. All pictures were taken using a Canon T7i DSLR with a 250 mm lens and a variety of lens settings. Pictures have been zoomed in and cropped from their original 6000×4000 size to 1920×1280.
   Salt-marsh wetlands panorama looking toward the southwest

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

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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