Moon – Saturn Conjunction

   Mid-evening Monday July 15th as the nearly full Moon rises it will be in a close conjunction with the outer ringed planet Saturn. The two will be separated by about 1-2o and both will easily fit within the field of view of binoculars, or a wide field telescope eyepiece.

   
   
   

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Moon – Jupiter Conjunction

   Saturday evening July 13th the 11-day old waxing gibbous Moon will be about 2o from the outer ringed planet Jupiter as the two rise in the east around sunset local time. Both will nicely fit within the field of view of binoculars.
   Using the binocular field of view (FoV) as a ‘ruler’ shift the binoculars about 1 FoV to the west, right, putting Jupiter on the left edge of the FoV and the reddish star Antares will be at the right edge.

   
   
   

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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Saturn at Opposition – 2019

   Tuesday July 9th the outer planet Saturn reaches its orbital position known as opposition. This is a position which has the faster moving Earth passing Saturn and at opposition is centered between the outer planet and the Sun. Picture the arrangement with the Moon at full phase; Sun – Earth – Moon, and that is similar to the arrangement for Saturn at opposition.
   When an outer planet, like Saturn, reaches opposition that planet rises around local time for sunset and is visible all night.
   The 7.5-day old waning gibbous moon will be west from Saturn and a few degrees above the bluish-white star Spica in Virgo the Harvest Maiden – both over the southwestern horizon. Look for the planet Jupiter and the reddish star Antares, the ‘heart’ of Scorpius the Scorpion to be just to the west from Saturn.

   
   
   
   
   

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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Earth at Aphelion – 2019

Earth at Perihelion   Thursday July 4th, as the Earth continues its annual trek around the Sun, the Earth reaches a point in its orbit that is called aphelion. Aphelion is the greatest distance that separates the Earth from the Sun, and we are the furthest from the Sun for the year at this point in the orbit. So, at 23 UT (6 pm CDT) on Thursday July 4th the Earth is 1.01670 AU (94,508,169 miles; 152,096,155 km) from the Sun.
   Approximately one-half year or one-half revolution earlier, on January 3rd, the Earth was at perihelion, its minimum distance from the Sun for this year (0.9833 AU (91,403,445 miles; 147,099,586 km). This difference, about 3%, 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.
   

   
   
   

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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July Moon at Ascending Node

   Wednesday July 3rd the 1.5-day old waxing crescent 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 the day of the node crossing the thin waxing crescent Moon will be close to the planets Mars and Mercury, however all three are low over the western horizon as the Sun is setting. Since this node crossing was close to the new Moon phase, about 12 hours after, there was a total solar eclipse. Visible from the Southern Hemisphere, Chile and Argentina.

   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.


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Total Solar Eclipse – Southern Hemisphere Only

   Tuesday July 2nd the new Moon will be about 12 hours away from crossing the plane of the ecliptic, its ascending node. When a node crossing is close to new Moon phase, or full Moon, there will be an eclipse. On July 2nd there will be a total solar eclipse visible throughout the day along a curving path of totality starting southwest of the Pitcairn Islands in the South Pacific Ocean then crossing the Pacific coast of Chile and on to the Atlantic coast of Argentina. The eclipse ends as the Sun is setting for the residents of Buenos Aires.
   Click here to go to the Hermit Eclipse web site for information including a detailed map and eclipse stage times

   
   
   

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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June Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Sunday June 23rd. At that time the Moon will be at a distance of 31.71 Earth diameters 251,374 miles (404,548 km) from the Earth.

   The 20-day old waning gibbous Moon rises around midnight local time and sets later that same day.

   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)

   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 go to bobs-spaces.


Also Follow me and other great resources at Feedspot.