Sun Not in Aries But it is The March 2017 Equinox

   Monday March 20th is an equinox day. This means that for those in the northern hemisphere winter is ending and spring has ‘sprung’ (starts). For our counterparts south of the equator summer is ending and fall is beginning. 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 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 10:29 UT on the 20th (05:29 am CDT) 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 within the constellation of Pisces the Fishes and not just 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.

sun-earth   Click here to go to the NASA Sun-Earth Days web site.

   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 Picses

11 March 2014   Saturday 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.

Sun Not in Pisces

The view from Earth - 18 February.

The view from Earth – 18 February.

  According to the pseudoscience of astrology the Sun enters the constellation of Pisces the Fishes on Saturday February 18th. In fact the actual position of the Sun is still within the boundary of the constellation of Aquarius the Water Bearer, as this graphic shows. The Sun had just entered Aquarius 2 days ago.

   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.
   
   
   
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 Aquarius – 2017

feb-view from earth   Thursday February 16th 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 Saturday February 18th when the sun is not in Pisces according to astrology.

   
   
   
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 Capricorn and Aquarius

ww   Thursday January 19th at 14 UT the Sun in its apparent eastward motion along the ecliptic enters the boundaries of the constellation Capricorn the Sea Goat. This is the true or actual position of the Sun. However 7 hours later, at 21 UT, according to the pseudoscience of astrology, the Sun,will enter the constellation of Aquarius the Water Bearer.

   
   
   

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.

Moon Moons Uranus

   Thursday January 5th the just past first quarter Moon, a waxing gibbous Moon, is close to the outer planet Uranus, and also two of the Dwarf Planets. But close only in the sense that the three are in the same direction, or line of sight. Uranus as the next-to-last outermost of the 8 planets is 19.8 Au and has an apparent magnitude of 5.8. Ceres and Eris, while both are Dwarf Planets, are at very nearly the opposite ends of the solar system. Ceres is within the asteroid belts at a distance of 2.5 AU and has an apparent magnitude of 7.64. Eris, on the other hand is 96 AU from the Earth and has an apparent magnitude of 18.6.

   
   
   

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.

Earth at Perihelion 2017

Earth at Perihelion   Feel the Heat?
   Wednesday January 4th at 14 UT (8 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 the Earth, this year, is 0.98330 AU (147,101,082 km; 91,404,374 miles) (compared with last year 2016: 0.98331 AU (147,099,586 km; 91,403,445 miles) from the Sun. Approximately one-half year or one-half revolution later, on July 3rd, the Earth is at aphelion and is 1.01668 AU(94,506,310 miles; 152,093,163 km), its maximum distance from the Sun for 2017. This difference 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.
   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.