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.

This video doesn’t exist
            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.

A View From Mars

   I was looking at this picture from the other evening I got to thinking about the Rovers on Mars would see if they looked toward the Earth?

   So as you wonder about that question, here is a look at Mars, by NASA, from last century (I love saying that instead of many years ago!), using data from the first Mars Orbiters. Take a simulated fly over the Martian surface above Mariner Valley and the large Martian volcanoes. Appropriately titled “Mars, the Movie”.

   What would Earth look like from the surface of Mars?
Here is a picture of Earth taken by the Rover Curiosity.

   Here is what it looks like using Starry Night Pro 8+ software to model the view from the latitude and longitude of the Perseverance Rover landing site in Jezero Crater, (18.4446°N 77.4509°E).
(The viewing location is correct however for depicting the Martian surface my software uses a view at the landing site for the Sojourner Rover.)


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.

March Equinox – 2021

   Saturday March 20th is an equinox day. While typically called the Vernal or Spring Equinox it is more globally appropriate to call this day the March Equinox as it is the start of Fall in the Southern Hemisphere. The official time for the equinox is 09:40 UT on the 20th which for my time zone is 5:40 am CDT. So for those in the northern hemisphere winter is ending and spring has ‘sprung’ (starts). From a geographical perspective we would describe the Sun as being over the Earth’s equator, and as this graphic shows there would be an equal amount of daylight and night on our planet as a result.
    At mid-day on the equator the sun is directly overhead and from that latitude you have no elongated shadow, just a ‘blob-like’ shadow at your feet as this picture of my feet taken at mid-day in Quito Ecuador shows.

    Regardless of your hemispheric preference get outside and cast a shadow!

  Northern hemisphere spring, Astronomically speaking, is when the Sun reaches the celestial coordinates of 0 hours and 0 degrees as it moves northward along the ecliptic crossing the celestial equator. At this location the Sun is just within the constellation of Pisces the Fishes and not entering Aries the Ram as the pseudoscience of astrology would have you believe.

    To learn more about the celestial coordinates click here to read a previous post about seasons and the equinox.

   Click here to see the online world sunlight map used to make the day/night graphic at the top of the page.

   Celebrate Solar Week March 22nd-26th. Click here to go to the Solar Week web site.

   During a trip to Quito Ecuador to visit one of the exchange student we had hosted, and her family, we spent the day at a Museum on the equator, Mitad del Mundo. I brought along my over-sized protractor knowing in advance that we would be at the museum. So at mid-day I had my wife stand on the equator (yellow line) and hold a string to the top of her head while Cathy, a sister of our exchange student, held the protractor. This was done during the summer so the Sun was over the northern horizon at mid-day and the Sun’s angle above the northern horizon was around 75o.

   Here is a short series of hourly pictures taken during the day on the September equinox on the equator in Quito Ecuador at Collegio Menor San Francisco de Quito, a private school that I visited and did the SunShIP project with (Sun Shadow Investigation Project).


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.

Earthkam Week

   Several times each year a down-looking camera on the International Space Station (ISS) is made available by NASA for making picture requests for the surface of the Earth. The camera is the Sally Ride Earthkam and as the blog title says, this is Sally Ride EarthKam Week. As these pictures, show our planet has a remarkably diverse surface.
   A popular thing to do is choose an orbital path and follow it across a part of the Earth you are interested in. Maybe where you live, a place you have visited or want to visit? Zoom in to see more detail, especially where the orbital path (the red one – for daylight), crosses. If satisfied click on the red line and make your request.
   Participating in the program requires registering so you can receive e-mail notifications of the next Earthkam week. I am registered as a classroom Teacher however any educator may apply. This would be great for Scout groups, or any other group interested in learning more about our planet, not to mention learning about NASA and its missions to Earth as well as off world endeavors.

                        Pictures from March 3-5 2021 Earthkam Week


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.

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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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.
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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January Apogee Moon

   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Thursday January 21st. For this apogee the 9-day old waxing gibbous Moon will be at a distance of 31.70 Earth diameters, 251,282 miles (404,400 km) from the Earth.

   On the date of the apogee, and high above the southwestern horizon, is the 8-day old waxing gibbous Moon. The Moon will be about 7o to the east from the planet Mars, and about 9o from the outer planet Uranus.

   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
   *Click here to read my Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)


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

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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.

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.

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2020-Winter Solstice

sag-cap-ani   According to the pseudoscience of astrology the Sun enters the constellation of Capricornus the Sea Goat this month when in fact the actual position of the Sun is still within the boundaries of the constellation of Sagittarius the Archer.
   In Astronomical terms the December Solstice is official when the Sun will have reached the celestial coordinates of 23.5o degrees south declination; 18 hours right ascension. With regard to the Earth’s surface this places the Sun over the Tropic of Capricorn, which is at 23.5o south latitude. We also know that it is the Earth’s tilt on its axis that is the cause for seasons on Earth rather than the distance between the Earth and the Sun. And of course we know that this signals the start of northern hemisphere winter and the southern hemisphere summer seasons.

   The official time for the change of seasons is at 10:01 UT on Monday December 21st, or 5:01 am CST.

   And for those ‘insanely curious’ like me, while the Sun is at 23.5o South declination and ‘in’ Sagittarius the Earth is opposite at 23.5o North declination and at the feet of the Gemini Twins.

   The animated graphic below sets the stage, so to speak, to illustrate the Sun’s actual location with respect to the zodiac constellations in the background. This is as opposed to the location of the Sun according to the pseudoscience of Astrology. The scene is set for 12:15 CST, or mid-day when the Sun is at an azimuth of 180o, or south, and is mid-way between rising and setting. Starting with the Sun at mid-day the scene changes as first the daytime sky is turned off, followed by the horizon being turned off.
   This leaves a sky view like during a total solar eclipse except that the Sun is not blocked out by the new Moon. And like during that solar eclipse the zodiac constellations in the background become visible.
   Then the following are added starting first with Sagittarius, then Capricorn, and then the ecliptic and celestial equator are added to show the relationship between the two constellations and what makes them plus another 11 constellations the astronomical zodiac of 13 constellations. The animation ends with the addition of the constellation boundary lines and labels for the rest of the constellations in this setting.
   It is the ecliptic, the apparent path of the Sun which, if it crosses the boundary of a constellation, makes that constellation one of the zodiac. And during December the Sun’s apparent path takes it across the constellation of Sagittarius rather than Capricorn.

   Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.


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.

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