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).

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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.

Sun Enters Astronomical Constellation Pisces the Fishes

11 March 2014   Thursday March 11th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Aquarius the Water Bearer and into the constellation of Pisces the Fishes. 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.
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.

Neptune at 2021 Solar conjunction

   Wednesday March 10th the outer ringed planet Neptune will reach a point in its respective orbit where Neptune will be on the opposite side of the Sun as viewed from here on Earth. Neptune, or any of the other outer planets (Mars to Neptune), dwarf planets, or small solar system bodies beyond the Earth’s orbit, will all eventually reach this position on the opposite side of the Sun known as solar conjunction.
   For the two inner planets, Mercury and Venus, when they are at a similar position on the opposite side of the Sun, they are at superior conjunction.
   
   
   

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.

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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Sun Is in Capricornus not Aquarius


   Tuesday January 19th at 15 UT the Sun in its apparent eastward motion along the ecliptic enters the boundaries of the constellation Capricornus the Sea Goat. This is the actual location of the Sun.
   Interestingly, according to the pseudoscience of astrology, 6 hours later, at 21 UT Tuesday January 19th, the Sun should be entering the constellation of Aquarius the Water Bearer.

   
   
   

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Grand Conjunction Part 2: A Triple Conjunction!

   Just when you thought it was over, it is not! Yes Jupiter and Saturn are certainly low over the western horizon and both are setting closer to sunset, however…
   The innermost planet Mercury will be passing by Saturn then Jupiter over the next several evenings (January 7th to 12th) in a series of conjunctions as the graphics below are showing.
   Each of the conjunctions brings the three planets all within the field of view of binoculars and should make for an interesting contrast in apparent magnitudes. Jupiter: -1.94; Saturn: 0.60; Mercury: 0.89.

   
   
            Be careful observing because the Sun is close.

   
   
   

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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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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Sun Enters Sagittarius

   Friday December 18th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Scorpius the Scorpion 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.

   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.

   
   
   

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A December Moon 3 for 1

                              New Phase, Descending Node, and a Solar Eclipse!

   Monday December 14th the new 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. This is an event that happens 2-3 times each month, but when a node crossing happens at new or full Moon phase there will be either a solar eclipse at new Moon or a lunar eclipse at full Moon.
   It’s all about timing, and the closer the node crossing time is to the time for the new or full phase that increases the chances for an eclipse. The time for the descending node crossing is 11:00 UT December 14th and the time for new Moon phase is about 5 hours later at 16:16 UT.

   So we get a total solar eclipse this time around. Hopefully my two camera amigos in Esquel Argentina will get some good pictures. Hint, hint Pablo y Checho!


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Sun Enters Ophiuchus-2020

ophiuchus   Sunday, November 29th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Scorpius the Scorpion and into the constellation of Ophiuchus the Healer. 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-scorpion   Ophiuchus is the 13th constellation of the zodiac (Astronomical) but does not appear in the astrological zodiac nor in the astrology column found in many newspapers. A constellation of either zodiac is defined the same way, using the ecliptic path. If the ecliptic passes through a constellation boundary then that constellation is a zodiac constellation. In the graphics I use the ecliptic path clearly crosses across the boundary for the constellation Ophiuchus the Healer.

   Ophiuchus is described in a mythology story as a healer. In one story following a mortal fight between Orion and Scorpius the Scorpion Ophiuchus kills the scorpion by stepping on it; extracts the venom from the scorpion; and then uses it to bring Orion back to life.
cadeuces   In Ophiuchus’s hands he is holding a long snake, the 2-part constellation of Serpens – Serpens Cauda (tail of the snake) and Serpens Caput (head of the snake). There are many stories about Ophiuchus and the snake including one where this is the origin of the symbol for medicine, the caduceus. However the caduceus is used primarily in the United States as the symbol for medicine, and is depicted as 2 snakes wrapped around a staff with wings. rodIf there is a connection with a medical symbol then it should be with the Rod of Asclepius, a staff with one snake.


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