Conjunction – Elongation – Conjunction

   Saturday evening watch for the 11-day old waxing gibbous Moon to be in conjunction with and about 3o from the reddish star Aldebaran in the constellation Taurus the Bull.

   Earlier in the evening the innermost planet Mercury was visible over the western horizon shortly after sunset. Mercury, on this date, will be at its Easternmost Elongation for this orbit. At elongation, eastern or western, Mercury, and also Venus, will be as far ‘out’ from the Sun to the right or left as we see the inner planets from Earth. At eastern elongation the inner planets follow the Sun across the sky during the day and appear as evening planets over the western horizon. At western elongation the inner planets ‘lead’ the Sun across the Sky during the day which means they rise ahead of the Sun and are seen as morning planets.

   But Wait – there’s still more!
   Saturn reaches solar conjunction on this date. During solar conjunction for an outer planet that outer planet will either be too close to the Sun to be seen or is on the opposite side of the Sun. When an outer planet reaches solar conjunction it moves from the evening skies to the morning skies.

   
   
   

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Sun Is in Capricornus not Aquarius


   Tuesday January 19th at 15 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 21 UT Tuesday January 19th, the Sun should be entering the constellation of Aquarius the Water Bearer.

   
   
   

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Waxing Crescent Moon – Mercury Conjunction

   Did you miss the 27-day old thin waning crescent Moon conjunction with Venus this past Monday morning? I did!
   Well there is an opportunity to see the thin crescent Moon on this side of new phase this Thursday evening January 14th. The 1.7-day young waxing crescent Moon will be over the western horizon in a line-up of sorts with Mercury, Jupiter, and Saturn all angled downward toward the western horizon. From Saturn to the Moon will span about 13o with Mercury, about 3-4o to the west, (down to the right) being the closest of the 3 planets.

   This animated graphic is set for 2-minute intervals starting at 5:30 pm CST.

   
   
   

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Morning and Evening Conjunctions

   Monday morning and evening, January 11th, offer an opportunity for catching a pair of conjunctions. Low over the eastern horizon at sunrise is the 27.7-day old very thin waning crescent Moon about 3-4o from the inner planet Venus.

   This could be a chance to see the Moon when it is about 24-hours from its new phase.

   Low in the western horizon at sunset is the ongoing triple conjunction between Mercury, Jupiter, and Saturn. Monday evening will be the closest Mercury and Jupiter will be as Mercury continues moving eastward away from the two giant planets.

   
   
   
   
   
   
   
   
   

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Grand Conjunction Part 2: A Triple Conjunction!

   Just when you thought it was over, it is not! Yes Jupiter and Saturn are certainly low over the western horizon and both are setting closer to sunset, however…
   The innermost planet Mercury will be passing by Saturn then Jupiter over the next several evenings (January 7th to 12th) in a series of conjunctions as the graphics below are showing.
   Each of the conjunctions brings the three planets all within the field of view of binoculars and should make for an interesting contrast in apparent magnitudes. Jupiter: -1.94; Saturn: 0.60; Mercury: 0.89.

   
   
            Be careful observing because the Sun is close.

   
   
   

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Earth at Perihelion – 2021

   Feel the Heat?
   As the Earth continues its annual trek around the Sun, Saturday January 2nd at 13 UT (7 am CST), 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 this year, 2021, the Earth is 0.9833 AU; 91,403,445 miles; 147,099,586 km from the Sun.

   Approximately one-half year or one-half revolution later, on July 5th, the Earth is at aphelion and is 1.0167 AU (94,508,169 miles; 152,096,155 km), its maximum distance from the Sun for 2020. This approximately 3% difference in distances between perihelion and aphelion 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 Scope on the Skies column Solar Explorations.


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2020-Winter Solstice

sag-cap-ani   According to the pseudoscience of astrology the Sun enters the constellation of Capricornus the Sea Goat this month when in fact the actual position of the Sun is still within the boundaries of the constellation of Sagittarius the Archer.
   In Astronomical terms the December Solstice is official when the Sun will have reached the celestial coordinates of 23.5o degrees south declination; 18 hours right ascension. With regard to the Earth’s surface this places the Sun over the Tropic of Capricorn, which is at 23.5o south latitude. 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. And of course we know that this signals the start of northern hemisphere winter and the southern hemisphere summer seasons.

   The official time for the change of seasons is at 10:01 UT on Monday December 21st, or 5:01 am CST.
earth-in-gemini

   And for those ‘insanely curious’ like me, while the Sun is at 23.5o South declination and ‘in’ Sagittarius the Earth is opposite at 23.5o North declination and at the feet of the Gemini Twins.

   The animated graphic below sets the stage, so to speak, to illustrate the Sun’s actual location with respect to the zodiac constellations in the background. This is as opposed to the location of the Sun according to the pseudoscience of Astrology. The scene is set for 12:15 CST, or mid-day when the Sun is at an azimuth of 180o, or south, and is mid-way between rising and setting. Starting with the Sun at mid-day the scene changes as first the daytime sky is turned off, followed by the horizon being turned off.
   This leaves a sky view like during a total solar eclipse except that the Sun is not blocked out by the new Moon. And like during that solar eclipse the zodiac constellations in the background become visible.
   Then the following are added starting first with Sagittarius, then Capricorn, and then the ecliptic and celestial equator are added to show the relationship between the two constellations and what makes them plus another 11 constellations the astronomical zodiac of 13 constellations. The animation ends with the addition of the constellation boundary lines and labels for the rest of the constellations in this setting.
   It is the ecliptic, the apparent path of the Sun which, if it crosses the boundary of a constellation, makes that constellation one of the zodiac. And during December the Sun’s apparent path takes it across the constellation of Sagittarius rather than Capricorn.

   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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A December Moon 3 for 1

                              New Phase, Descending Node, and a Solar Eclipse!

   Monday December 14th the new 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. This is an event that happens 2-3 times each month, but when a node crossing happens at new or full Moon phase there will be either a solar eclipse at new Moon or a lunar eclipse at full Moon.
   It’s all about timing, and the closer the node crossing time is to the time for the new or full phase that increases the chances for an eclipse. The time for the descending node crossing is 11:00 UT December 14th and the time for new Moon phase is about 5 hours later at 16:16 UT.

   So we get a total solar eclipse this time around. Hopefully my two camera amigos in Esquel Argentina will get some good pictures. Hint, hint Pablo y Checho!


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Sun Enters Ophiuchus-2020

ophiuchus   Sunday, November 29th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Scorpius the Scorpion and into the constellation of Ophiuchus the Healer. 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-scorpion   Ophiuchus is the 13th constellation of the zodiac (Astronomical) but does not appear in the astrological zodiac nor in the astrology column found in many newspapers. A constellation of either zodiac is defined the same way, using the ecliptic path. If the ecliptic passes through a constellation boundary then that constellation is a zodiac constellation. In the graphics I use the ecliptic path clearly crosses across the boundary for the constellation Ophiuchus the Healer.

   Ophiuchus is described in a mythology story as a healer. In one story following a mortal fight between Orion and Scorpius the Scorpion Ophiuchus kills the scorpion by stepping on it; extracts the venom from the scorpion; and then uses it to bring Orion back to life.
cadeuces   In Ophiuchus’s hands he is holding a long snake, the 2-part constellation of Serpens – Serpens Cauda (tail of the snake) and Serpens Caput (head of the snake). There are many stories about Ophiuchus and the snake including one where this is the origin of the symbol for medicine, the caduceus. However the caduceus is used primarily in the United States as the symbol for medicine, and is depicted as 2 snakes wrapped around a staff with wings. rodIf there is a connection with a medical symbol then it should be with the Rod of Asclepius, a staff with one snake.


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November Moon at Apogee – And the Ecliptic

click on graphic to see it larger   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Thursday November 26th. For this apogee the 12-day old waxing gibbous Moon will be at a distance of 31.82 Earth diameters, 252,211 miles (405,894 km) from the Earth.

   On the date of the apogee the 12-day old waxing gibbous Moon will be about 12o to the east from the planet Mars. The Moon will also be about 11o west from the outer planet Uranus. Currently Uranus has an apparent magnitude of around 5.7 meaning that it could be seen with the unaided in dark enough skies, or with telescopes and even binoculars – as long as the Moon is not in that part of the sky.

   Along the Ecliptic
   You may notice the arrangement of the planets spread across the horizon as shown in the graphic. Many objects in our solar system orbit the Sun in a path that is somewhat parallel with the Earth’s orbit, the ecliptic. All of the orbits are tilted or inclined away from the ecliptic however the 8 classical planets all have orbits that are inclined less than 7o from the ecliptic. Dwarf planets, asteroids, comets, for example, have orbital inclinations greater than 7o.
   The ecliptic also defines the Sun’s apparent path against the background of stars throughout the year. The planets are also in motion as they orbit the Sun as the video below illustrates.
   Take a short cruise along the ecliptic with the Sun!


   Does our Moon actually go around the Earth as this graphic shows? 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)
   
   
   
   

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