January Moon at Descending Node


   Wednesday morning January 22nd the waning crescent 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.

   On the date of the descending node the 27-day old thin waning crescent Moon will be about 4o to the west from the outer ringed planet Jupiter. Both rise within an hour of local time for sunrise.

   
   
   
   
   

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Sun Enters Capricornus not Aquarius- – 2019


 Monday January 20th at 9 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 15 UT Monday January 20th, the Sun should be entering 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.


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January Moon at Ascending Node

   Wednesday January 9th the 14.8-day old nearly full Moon rises between the legs of the Gemini Twins. The Moon will be about 14-15o to the west from the ‘Twin’ Stars Pollux and Gemini.

   As it is rising the Moon will be crossing the plane of the ecliptic moving north. 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.

   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)

   

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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Where is Jupiter?

   For the past several months the outer planets Jupiter and Saturn have been the brightly shining ‘evening stars’ over the western horizon at sunset. They have recently been joined by the inner planet Venus, but at the same time as Venus has become more prominent each evening Jupiter and Saturn have been setting earlier as they gradually move closer to the horizon at sunset.

   And now Jupiter is no longer in the ‘picture’. So what happened to Jupiter, and will soon happen to Saturn? All solar system objects orbiting the Sun beyond Earth’s orbit move at a slower pace around the Sun than the Earth. The Sun has an apparent motion toward the east which is the same as the Earth’s actual motion. So what happens is that over time the Sun catches up with Jupiter, then Saturn. Eventually the Sun passes them and the planets become visible in the morning skies rising ahead of the Sun.

   At some point along their respective orbital path they will be on the opposite of the Sun from the Earth. This is known as solar conjunction, and that is where Jupiter will officially be on Friday December 27th.

   
   
   

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 Does Enter Sagittarius

16dec-view-from-earth   Wednesday December 18th 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. Ophiuchus the Healer is the 13th Astronomical Zodiac constellation based on the location of the ecliptic and the Sun’s actual position relative to the stars and constellations in the background.

   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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December Moon at Ascending Node

   Friday December 13th the 17.5-day old waning gibbous Moon rises between the legs of the Gemini Twins. The Moon will be about 10-11o to the west from the ‘Twin’ Stars Pollux and Gemini. As it is rising the Moon will be crossing the plane of the ecliptic moving north. 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.

   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)

   

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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Tales Along the Ecliptic

   Once in a while the planets are arranged such that they are spread across the sky as they look in this graphic. However over time, several days, this arrangement changes as the planets continue moving along their orbits.
   The planets are not lined up in a straight line outward from the Sun but rather are arranged along the ecliptic. The ecliptic is the Earth’s orbital path around the Sun and the respective orbit of each planet is inclined from the ecliptic. And this is one of those times when it is easy to visualize the ecliptic. Click here to read a previous posting about the ecliptic and planet inclination.

   This animated graphic is showing the terrestrial planets as they move along their respective orbits for this month. They are not ‘lined up’ as they appear to be in the above horizon picture.

   This graphic shows the solar system out to Neptune and from this perspective the planets are obviously not in a straight line on December 1st.

   
   
   

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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