June 2019 Solstice

   Northern hemisphere spring comes to an end and the summer season begins on Tuesday June 21st at 8 UT (3 am 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 of the Earth’s equator. At this same time the Sun is just entering the boundaries of the astrological constellation Cancer the Crab. Interestingly about 19 hours later, Wednesday June 22nd at 3 UT (10 pm CDT June 21st) the Sun will actually be entering the region of the Gemini Twins as it crosses the boundary between Gemini and Taurus.

   According to the pseudoscience of astrology the Sun, at this date, would be entering the astrological sign of Cancer the Crab.

   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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2015 June Solstice

21june-ecliptic   Northern hemisphere spring comes to an end and its summer begins on Sunday June st at 16:38 UT (11:38 am 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 the Sun is still within the boundaries of the constellation Taurus the Bull – but just barely. Interestingly about 12 hours later, June 22nd at 2 UT (June 21st – 9 pm CDT) the Sun ‘will move’ into the region of Gemini as it crosses the boundary between Gemini and Taurus.
   According to the pseudoscience of astrology the Sun, at this date, would be entering the astrological sign of Cancer the Crab.
Just had to include this!!   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.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Sun Not in Capricornus aka the December Solstice

  According to the pseudoscience of astrology the Sun enters the constellation of Capricornus the Sea Goat on Sunday December 21st, when in fact the actual position of the Sun is still within the boundaries of the constellation of Sagittarius the Archer.

Click on graphic to see it full size.

Click on graphic to see it full size.

   In reality on Sunday December 21st at 23:03 UT, 5:03 pm CST, the Sun will have reached the celestial coordinates of 23.5o degrees south; 18 hours right ascension. With regard to the Earth’s surface this places the Sun over the Tropic of Capricorn, which is also 23.5o south. We know that this signals the start of northern hemisphere winter and the southern hemisphere summer seasons. 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.
   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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Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

December Solstice 2013

sagittarius-dec21   On Saturday, 21 December, at 11:11 CST (17:11 UT) the Sun will have reached its southernmost distance (in degrees of latitude and/or declination) from the Earth’s surface and celestial equator. Using Geographical coordinates the Sun is over the Tropic of Capricorn at a latitude of 23.5o South. Using Astronomical coordinates the Sun is -23.5o South (declination) and 18Hours RA (right ascension).

December Solstice
seasons   In its annual trek around the Sun the Earth reaches certain orbital positions that define the beginning and end for each of our four seasons. In either hemisphere, northern or southern, we learn these as the spring equinox, summer solstice, autumn equinox, and winter solstice. However the seasons are reversed or the opposite for each hemisphere. Winter in the northern hemisphere, for example, starts when summer in the southern hemisphere begins, and so on. This gives rise to the idea that it may be more practical to simply refer to these dates by the month that it occurs in. So for example rather than saying this is the “winter solstice” and then specifying which hemisphere you are referring to folks in either hemisphere would know which solstice, equinox, and or season it is by simply stating the name of the month for that event, i.e., December Solstice, March Equinox, June Solstice, September Equinox.

Along the Ecliptic
   How are the dates for these changes of seasons selected? As the Earth revolves around the Sun the Sun appears to move eastward against the stars in the background, regardless of the hemisphere. The apparent path the Sun follows is known as the ecliptic and in reality it is the orbit of the Earth superimposed on the stars in the background. seasons on ecliptic-aniAs a rule the starry sky is referred to as the celestial sphere, an imaginary sphere surrounding the Earth on which the ecliptic, stars, planets, and our Moon are located. The Earth’s equator and lines of latitude and longitude are likewise superimposed on the celestial sphere. This is a system similar to the use of latitude and longitude on the Earth’s surface that allows for the positioning or plotting of celestial objects including stars, galaxies, and closer to home the location of the Sun and orbiting planets.

   With regard to the Sun there are specific locations along the ecliptic that mark the change of seasons that correspond to geographic locations on the Earth’s surface. In the northern hemisphere we traditionally say that the Winter Solstice (change to December Solstice) (first day of winter) occurs when the Sun is south of the equator over the Tropic of Capricorn. The Spring Equinox (change to March Equinox) (first day of spring) is when the Sun is over the Earth’s equator. The first day of summer or the Summer Solstice (change to June Solstice) is when the Sun is north of the equator and is over the Tropic of Cancer. And finally when the Sun is back over the Earth’s equator it is the Autumn Equinox (change to September Equinox) and the start of autumn.

Mid-day Sun at 40oNorth

Mid-day Sun at 40oNorth

   These dates are more precisely determined by when the Sun has reached a specific astronomical coordinate on the celestial sphere. However without knowing the calendar date or astronomical position one can easily determine this date by observing the Sun’s apparent daily path regularly.
   In the northern hemisphere on the first day of winter during December the Sun will be south of the equator and will follow the shortest apparent path from east to west. It will rise in the southeast at its furthest south point from due east and set in the southwest at its furthest south point from due west. Midway between rising and setting the Sun will be at its lowest mid-day point above the southern horizon. In contrast it is the start of summer in the southern hemisphere during December. From those latitudes the Sun will follow its longest apparent path from east to west. The Sun will rise in the southeast at its furthest south point from due east and set in the southwest at its furthest south point from due west. Midway between rising and setting the Sun in the southern hemisphere would be at its highest mid-day point above the northern horizon.

The View From South of the Equator
   Keep in mind that these observations are based on the direction one typically faces to view the apparent path of the Sun follows between rising and setting. This direction is always toward or relative to the Earth’s equator and is centered mid-way between due east and due west. It is also latitude-dependent in that the length of daylight and night varies with latitude – more hours of daylight close to the equator where the Sun’s apparent path takes it higher above the horizon and subsequently giving more time above the horizon. Moving away from the equator the Sun’s apparent path doesn’t take it as high above the horizon and thus less daylight time. Nonetheless those in the northern hemisphere face toward south while those in the southern hemisphere face toward north. Remember – the Sun and all other celestial objects always rise in the east!

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Sun Enters Sagittarius Today

Click on graphic to see it full size.

Click on graphic to see it full size.

   On 18 December at 7 UT, 1 am CST, 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.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

June Solstice

Sun's Apparent Motion Along the Ecliptic

Sun’s Apparent Motion Along the Ecliptic – from Taurus to Gemini

   Northern hemisphere spring comes to an end and its summer begins at 12:04 am CDT (05:04 UT) on 21 June as the Sun ‘reaches’ the celestial coordinates of 23.5oN and 6 hours right ascension. With respect to the Earth’s surface the Sun is described as over the Tropic of Cancer, 23.5oN of the Earth’s equator. At this same time the Sun is still within the boundaries of the constellation Taurus the Bull – but just barely. Interestingly 9 hours later, (9:00 am CDT – 14 UT), the Sun ‘will move’ into the region of Gemini as it crosses the boundary between Gemini and Taurus.
   We know that it is the Earth’s orbital motion around the Sun giving rise to the sun’s apparent eastward motion amongst 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 the limited to northern hemisphere term summer solstice.

   Follow the seasons by observing how vegetation changes during 1 year. The video below was produced by an Earth orbiting satellite operated by the NASA/NOAA Suomi National Polar Orbiting Partnership (NPP). It is a really interesting narrated tour of the Earth from orbit over a variety of geographic features and landscapes.

Just had to include this!!

Just had to include this!!

   
   

   Click here to go to the Qué tal in the Current Skies web site for more observing information.