Earth at aphelion – 2020

   Saturday July 4th, as the Earth continues its annual trek around the Sun, the Earth reaches a point in its orbit that is called aphelion. Aphelion is the greatest distance that separates the Earth from the Sun, and we are the furthest from the Sun for the year at this point in the orbit. So, at 12 UT (7 am CDT) on Saturday July 4th the Earth is 1.0167 AU (94,507,635 miles, 152,095,295 km) from the Sun.
   Approximately one-half year or one-half revolution earlier, on January 5th 2020, the Earth was at perihelion, its minimum distance from the Sun for this year at 0.9832 AU (91,398,199 miles : 147,091,144 km). This difference, about 3%, in distances 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.
   

   
   
   

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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June Solstice – 2020

   Northern hemisphere spring comes to an end and its summer begins on Saturday June 20st at 21:45 UT (4:45 pm CDT) when the Sun ‘reaches’ the celestial coordinates of 23.5o north declination and 6 hours right ascension. With respect to the Earth’s surface the Sun is described as over the Tropic of Cancer, 23.5o, north latitude of the Earth’s equator. At this same time according to astrology the Sun is said to be entering the boundaries of the astrological constellation Cancer the Crab. Actually it is not. Interestingly about 7 hours later, June 21st at 9 UT (4 am CDT) the Sun will actually be entering the region of the Gemini Twins as it crosses the boundary between Gemini and Taurus.

   We know that it is the Earth’s orbital motion around the Sun that causes the sun’s apparent eastward motion among the stars in the background. This is how the Sun ‘reaches’ a celestial coordinate, how it ‘crosses’ the boundaries between constellations, or how it is ‘in’ a constellation.

   With respect to the southern hemisphere this is the end of their summer and start of their fall season. So thinking globally my preference has been to use the name of the month to designate the season change. Hence the use of the term June Solstice rather than summer solstice.

   
      
   

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 Not Really In Cancer

   According to the pseudoscience of astrology the Sun enters the constellation of Cancer the Crab on Sunday June 21st at 9 UT (4 am CDT). When in fact the actual position of the Sun on this date is still within the boundary of the constellation of Taurus the Bull, but by very little. The Sun is very close to the eastern boundary for Taurus and the western boundary for the Gemini Twins, as this graphic and the banner graphic at the top of the page shows.
   Interestingly the June solstice was yesterday
   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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Sun Not in Gemini

  According to the pseudoscience of astrology the Sun enters the constellation of the Gemini Twins on Wednesday May 20th. When in fact the actual position of the Sun on this date is still within the boundary of the constellation of Taurus the Bull, as this graphic and the banner graphic show.

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 more observing information for this month.

Sun Enters Taurus the Bull – 2020

   Wednesday May 13th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Aries the Ram and into the constellation of Taurus the Bull. 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.


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Sun Not In Taurus – 2020

April 19th  According to the pseudoscience of astrology the Sun enters the constellation of Taurus the Bull on Sunday April 19th. When in fact the actual position of the Sun on the 19th is within the boundary of the constellation of Aries the Ram, as this graphic shows. Actually the Sun had just entered Aries the day before on April 18th.

   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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Sun Enters Aires – 2020

April 19th   Saturday April 18th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Pisces the Fishes and into the constellation of Aries the Ram. 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.


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The Moon and the Lion

   Saturday April 4th the 11.5-day old waxing gibbous Moon will be high above the southern horizon at sunset local time and the Moon will be about 4-5o from the heart of Leo the Lion, the star Regulus.

   If your skies are clear look toward the west for Venus to be very close, on the east side, of the open star cluster the Pleiades. Both will easily fit within the field of view of binoculars or a telescope with a low-magnification eyepiece.

   
   
   

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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Solar Opposites

   Inner planets like all the planets as viewed from Earth appear to be moving from one side of the Sun to the other. As a result the visible planets are seen either in the morning skies when located west from the Sun and rising before the Sun rises, or in the evening skies east from the Sun, and setting after the Sun sets. For the two inner planets, Mercury and Venus, these positions on either side of the Sun are known as elongations – western or greatest western elongation and its counterpart, eastern or greatest eastern elongation.
   As the graphics below show, both inner planets reach their respective elongations – but on opposite sides of the sun. Monday March 23rd Mercury is at western elongation in the morning skies, and on Tuesday March 24th Venus will be at eastern elongation in the evening skies.

   
   
   

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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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).

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