Mercury at Inferior Conjunction

   Friday March 15th the innermost planet Mercury reaches inferior conjunction. At inferior conjunction Mercury will move between the Earth and the Sun – much like the position of the Moon at new phase. The graphic to the right shows the planet positions relative to the Earth and Sun for both inner planets and outer planets.

   At this inferior conjunction Mercury will not be directly in line with the Earth and the Sun – on the ecliptic. Mercury has an orbital inclination of 7o with respect to the ecliptic. So like our Moon, Mercury during each complete orbit, will cross the plane of the ecliptic moving north (ascending node) and also moving south (descending node). For this inferior conjunction Mercury will be north of the ecliptic, but angling south approaching its descending node toward the end of the month.

   
   
   

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Mercury at Eastern Elongation

orbital-positions    On Tuesday February 26th Mercury, the innermost planet, will reach its orbital position known as greatest eastern elongation. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows.
   From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – from superior conjunction, behind the Sun, out to the left (east) from the Sun to eastern elongation, then reverse and move westward through (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!
   I’ve added Mercury’s orbit to the ‘horizon view’ graphic below. Mercury is never very far ‘out’ from the Sun at elongation because of how close to the Sun is Mercury.
   Currently Mercury is visible over the western horizon at sunset local time. Joining Mercury to the east (up to the left) is the planet Mars. A few degrees west from Mars, (to the right), is the star Hamal. This is the brightest star in the small constellation of Aries the Ram.
   Additionally, if your skies are dark enough it should be possible to see the “Square of Pegasus”, a part of the constellation Pegasus the Winged Horse. And look for the star Mirach, part of the constellation Andromeda the Princess. Just a few degrees to its right is a fuzzy looking smear of light – M-31, the Andromeda Galaxy.
   
   
   

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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Mercury at Superior Conjunction

orbital-positions   Wednesday January 30th the innermost planet Mercury reaches superior conjunction. At superior conjunction Mercury will be on the opposite side of the Sun. The graphic to the right shows the planet positions relative to the Earth and Sun for both inner planets and outer planets.

   While at this superior conjunction Mercury will not be directly in line with the Earth and the Sun – on the ecliptic. Mercury has an orbital inclination of 7o with respect to the ecliptic. So like our Moon, Mercury during each complete orbit, will cross the plane of the ecliptic moving north (ascending node) and also moving south (descending node). For this superior conjunction Mercury will be south of the ecliptic and will reach its furthest position south of the ecliptic on February 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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Jupiter – Mercury Conjunction

   Friday and Saturday mornings, December 21st and 22nd, the outer planet Jupiter and the inner planet Mercury will be within a couple of degrees from each other. Both rise about an hour before sunrise local time and will easily fit within the field of view of binoculars.

   
   
   

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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Mercury at Western Elongation

   On Saturday December 15th Mercury, the innermost planet, will reach its orbital position known as greatest western elongation at 21.3o. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows. Even though it sounds confusing at western elongation for either Mercury or Venus the inner planet will be to the right of the Sun as we view them, meaning that at western elongation an inner planet rises in the east before the Sun rises. And at eastern elongation with the inner planet on the left side of the Sun the inner planet follows the Sun across the sky setting after the Sun sets.

   From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – out to the left (east) from the Sun to eastern elongation, then reverse and move westward (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!


   Mercury is visible in the morning skies just before sunrise local time, as this graphic shows. Venus, to the west from Mercury rises about 2 hours before Mercury, and Jupiter rises shortly after Mercury.

   
   
   
   
   

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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Thin Moon Conjunction with Mercury

   Wednesday morning December 5th the very thin 28-day old waning crescent Moon will be within 4-5o from the innermost planet Mercury. Venus shines very brightly above or west from the Moon. About an hour after the Moon and Mercury have risen the outer planet Jupiter will rise above the eastern horizon.

   
   
   

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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Mercury at Inferior Conjunction

orbital-positions   Tuesday November 27th the innermost planet Mercury reaches inferior conjunction. At inferior conjunction Mercury will move between the Earth and the Sun – much like the position of the Moon at new phase. The graphic to the right shows the planet positions relative to the Earth and Sun for both inner planets and outer planets.

   At this inferior conjunction Mercury will not be directly in line with the Earth and the Sun – on the ecliptic. Mercury has an orbital inclination of 7o with respect to the ecliptic. So like our Moon, Mercury during each complete orbit, will cross the plane of the ecliptic moving north (ascending node) and also moving south (descending node). For this inferior conjunction Mercury will be about 5o north from the ecliptic, approaching its maximum angle of 7o.

   
   
   

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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