2018 March Equinox

   Tuesday 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 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 16:15 UT on the 20th (11:29 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.


   Celebrate Solar Week March 19th-23rd. 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 Not in Pisces


  According to the pseudoscience of astrology the Sun enters the constellation of Pisces the Fishes on Sunday 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.

   
   
   

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.

Mercury at Superior Conjunction

mercury at superior conjunction
   Saturday February 17th the innermost planet Mercury reaches superior conjunction – on the opposite side of the Sun from the Earth. For those that are curious, Mercury at superior conjunction is approximately 1.384 AU (128,650,837 miles; 207,043,453 km) from the Earth – the combined distance of the Earth to Sun distance plus the radius of Mercury’s orbit.
   Mercury is not visible while in conjunction with the Sun but within the next week or so Mercury will reappear on the east side of the Sun and start becoming visible over the western horizon at sunset.

   
   
   

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.

August Moon at Ascending Node – and Oh Yeah, A Total Solar Eclipse!

   Monday August 21st the new Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.

   On August 21st the new Moon will be crossing the plane of the ecliptic at 10:34 UT (5:34 am CDT) within the constellation Leo the Lion. 8 hours later, at 18:30 UT (1:30 pm CDT), the Moon will reach new phase. This close timing between the new Moon phase and a node crossing means only one thing – eclipse!!

   My eclipse viewing area will be at an Elementary School in the North Kansas City School District. From that location totality will be approximately 80 seconds. This short video showing totality for 80 seconds, was clipped and edited from a video shot during the November 2012 total solar eclipse viewed from Australia.

   Read a bit more about this eclipse from a previous post.

      Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

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.

2017 June Solstice

21june-ecliptic   Northern hemisphere spring comes to an end and its summer begins on Wednesday day June 21st at 4:24 UT (11:24 pm CDT Tuesday June 20th) 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 just entering the boundaries of the astrological constellation Cancer the Crab. Interestingly about 11 hours later, June 21st at 15 UT (10 am CDT) the Sun will actually be entering the region of the Gemini Twins as it crosses the boundary between Gemini and Taurus.
Just had to include this!!
   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.

February Moon at Descending Node and a Solar Eclipse

26feb-descending-node
   Sunday February 26th the new Moon will be crossing 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. The time for new Moon phase 14:59 UT while the time for the node crossing is 8 hours earlier at 6:40 UT. Given the close times for the two events means that there will be a solar eclipse. However the Moon, because of its elliptical shaped orbit, will be at a further distance from the Earth such that it will appear smaller in diameter than the Sun appears. This means that at mid-eclipse, or totality, the Moon will not completely cover the Sun, instead there will be a ring of sunlight around the Moon. The ring of sunlight is called the annulus and so this is an annular solar eclipse. The eclipse will be visible from parts of southern Argentina and western central Africa.
annular-eclipse-ani   On my birthday in 1994 I was ‘honored’ to not only have an annular solar eclipse on that day but the eclipse path, the path of annularity, crossed right over where I live southeast of Kansas City Missouri. This animation is of the May 10th annular solar eclipse.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

Sun Enters Scorpius-2016

   Tuesday November 22nd the Sun, in its apparent eastward motion along the ecliptic, moves out of the constellation Libra the Scales and into the constellation of Scorpius the Scorpion. 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.