Planets and Stars in Motion

   Over the next several days (evenings) both inner planets, Mercury and Venus, are moving along their respective orbits approaching each planet’s eastern elongation. From the animated graphic you can see that the stars in the background, like the two ‘Twin Stars’ Pollux and Castor, are also moving but toward the western horizon. This is a regular motion of the stars caused by the Earth’s own orbit, revolution, around the Sun. As the Earth revolves the stars appear to move westward – a real motion not to be confused with the apparent motion of stars toward the west as the Earth rotates.

   On the evening of June 25th Mercury will pass within about 5-6o from the star Pollux.

   
   
   
   
   
   
   
   
   

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Moon Conjunction with Spica


   On the evening of June 21st the the 8-day old waxing gibbous Moon will be within about 8o from the blue-white star Spica in Virgo the Harvest Maiden. In two days the Moon will have moved further east and be close to the planet Jupiter.

   
   
   
   
   
   

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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2018 June Solstice

   Northern hemisphere spring comes to an end and its summer begins on Thursday day June 21st at 10:08 UT (5:08 am CDT) 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 according to astrology the Sun is said to be entering the boundaries of the astrological constellation Cancer the Crab. Interestingly about 11 hours later, June 21st at 21 UT (4 pm 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!!

   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.

Venus May Get Stung!

   Over the next few evenings, June 19th and 20th the inner planet Venus, as it orbits toward the east, will pass within about 0.5-1o from the open star cluster known as M-44, or the Beehive Cluster. Venus shines brightly with an apparent magnitude of -4.0 compared to the combined apparent magnitude of 3.7 for M-44. Further to the east is the first quarter Moon, but it should be far enough away so that its reflected light will not interfere too much with seeing the open star cluster.


   This should make for a great sight through binoculars or a wide-field view telescope eyepiece.

   
   
   
   
   
   
   
   
   

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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Moon Near Heart of the Lion

   Sunday evening the 4.3-day old waxing crescent Moon will be about 4o from the star Regulus, the heart of Leo the Lion. Spread across the sky from west to east are three planets, Venus, Jupiter, and 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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June Moon at Ascending Node

   Saturday June 16th the 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 Saturday evening June 16th the 3.5-day old waxing crescent Moon will be about 8o east (left) from the planet Venus and about 3o from the open star cluster, M-44 also, known as the ‘Beehive Cluster’.

   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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Moon Passes the Twins and Venus

   Friday evening June 15th the 3.75-day young waxing crescent Moon will be to the left from the ‘Twin’ stars of Pollux and Castor. A little further east or higher above the Moon is the ‘hard-to-miss’ planet Venus.

   Over the next 24 hours the Moon will have orbited eastward and by the same time Saturday evening June 16th the waxing crescent Moon will be ‘above’ Venus, or further east than Venus is.

   
   
   

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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