March Equinox – 2020

   Friday March 20th, this year-2020, is an equinox day. However depending on your local time zone the equinox may occur on the day before as the official time for the equinox is 03:54 UT on the 20th which for my time zone is 10:54 pm March 19th. Regardless, 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 officially (well at least astronomically) begins at 03:54 UT on the 20th which for my time zone is 10:54 pm March 19th 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 23rd-27th. 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).

This slideshow requires JavaScript.


   
   
   


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.


Also Follow me and other great resources at Feedspot..

Sun Does Enter Aquarius-2020

feb-view from earth   Monday February 17th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Capricornus the Sea Goat and into the constellation of Aquarius the Water Bearer. This is the true or actual position of the Sun as opposed to the pseudoscience of astrology which usually has the astrological Sun one constellation ahead or east from the Astronomical Sun’s position, which will be Wednesday February 19th when the sun is not in Pisces according to astrology.

   
   
   

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.


Also Follow me and other great resources at Feedspot.

Imbolog 2020

   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.

   
   
   

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.


Also Follow me and other great resources at Feedspot.

Mornings Have Hang Ups!

   Northern Hemisphere winter in addition to chilly or cold mornings may sort of warm you, at least in your mind. If you are outside looking at the sky, over the eastern horizon is a large triangular shape of three bright stars. One star each from three different constellations. Deneb in Cygnus the Swan, Vega in Lyra the Harp, and Altair in Aquila the Eagle. This is the asterism (star pattern but not a constellation) the Summer Triangle. There, warmer now?!
   So if you are outside checking out the Summer Triangle, or perhaps Mars and nearby Antares and you have an optical aid like binoculars or a lower power wide-field eyepiece in your telescope aim them and your eyes toward the star Altair. In dark enough skies you can make out the stars making up Sagitta the Arrow a few degrees away from Altair.
   As Altair is rising and with binoculars move the field of view up to the left until the stars of Sagitta fill the field of view. This small constellation, yes a constellation, could be used as a sort of pointer stars to look a few degrees away for a small open star cluster, Brocchi’s Cluster, or more commonly known as the ‘Coathanger Cluster’.
   So if mornings with stars like this don’t warm you up then wait a few months of Earth revolution and these same stars will be showing up in the warmer evening skies of Northern Hemisphere summer and fall.

   
   
   

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.


Also Follow me and other great resources at Feedspot.

Earth at Perihelion – 2020

   Feel the Heat?
   Sunday January 5th at 8 UT (3 am CST), as the Earth continues its annual trek around the Sun, 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, 2020, the Earth is 0.9832 AU (91,398,199 miles : 147,091,144 km) from the Sun.

   Approximately one-half year or one-half revolution later, on July 4th, the Earth is at aphelion and is 1.01669 AU (94,507,634 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 2011 Scope on the Skies column Solar Explorations.
   Here is a good classroom activity about the Earth’s orbit and its effect on the apparent size of the Sun: Why Does the Size of the Sun Appear to Change? A Year of the Sun.


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.


Also Follow me and other great resources at Feedspot.

Mid-Winter Skies

   Tuesday evening December 24th around sunset or after the skies darken look toward the western horizon and you can’t miss noticing the bright celestial object – the inner planet Venus. Also, despite the fact that we are now two seasons away from our summer (Northern Hemisphere), over the western horizon are three stars making up the ‘Summer Triangle’. These three stars each belong to a seperate constellation but together they form an asterism,not a constellation, but a recognizable star shape.

   Wednesday morning December 25th look toward the eastern horizon for the ‘Red Planet’ (Mars) to be above the horizon and about 15o from the reddish star Antares in Scorpius the Scorpion. In this graphic Antares is just above the horizon.
Higher above Mars, toward the right or the west, is a the bluish star Spica in Virgo the Harvest Maiden. And higher still but toward the left is another reddish star. This is Arcturus in Bootes the Herdsman.

   As this year and decade come to a close I’d like to thank all my readers and the universe in general for allowing me an opportunity to share things celestial.
Have a happy and safe Holiday however you celebrate.


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.


Also Follow me and other great resources at Feedspot.

Sun Does Enter Sagittarius

16dec-view-from-earth   Wednesday December 18th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Ophiuchus the Healer and into the constellation of Sagittarius the Archer. This is the true or actual position of the Sun as opposed to the pseudoscience of astrology which usually has the astrological Sun one constellation ahead or east from the Astronomical Sun’s position. Ophiuchus the Healer is the 13th Astronomical Zodiac constellation based on the location of the ecliptic and the Sun’s actual position relative to the stars and constellations in the background.

   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.


Also Follow me and other great resources at Feedspot.