Pluto at Opposition

orbital-positions   Monday July 6th at 10 UT (5 am CDT) the Dwarf Planet Pluto will be at opposition. All outer planets and other solar system objects that orbit the Sun beyond the orbit of the Earth have opposition. At that orbital position the Earth is between the Sun and the outer solar system object, much like the Sun-Earth-Moon arrangement for a full Moon. At opposition the outer solar system object rises at the local time for sunset and sets at the local time for sunrise – again just like the full Moon.

   Where is Pluto and is Pluto visible to the naked eye? Pluto currently is above the teapot-shaped asterism for Sagittarius the Archer. It is located near a 3rd magnitude star, Xi2 Sagittarii, however Pluto has an apparent magnitude of 14.0 making it too dim to be seen in other than a large telescope or with time exposure images.

Click here to learn more about the New Horizons mission and take part in the mission with some of the interactives created by NASA.

   
   
   
   

Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mercury at Inferior Conjunction

orbital-positions   Saturday May 30th at 17 UT (12 pm CDT) 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.

mercury at inferior conjunction   While at inferior conjunction Mercury is not 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). This past May 23rd Mercury was at its descending node, and for those thinking ahead Mercury crosses the ecliptic moving north (ascending north) next month on June 24th.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Uranus at Solar Conjunction

   Monday April 6th at 14 UT (9 am CST) the outer planet Uranus will be solar conjunction, a position where Uranus is on the opposite side of the Sun as seen from Earth. All of the planets, as viewed from Earth, will reach solar conjunction at some point during their orbit around the Sun. For the two inner planets, Mercury and Venus, this is known as superior conjunction rather then simply conjunction as it would be for the outer planets.

   
   
   
   
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Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Neptune at Solar conjunction

view-from-earth_neptune-solar-conjunction   Thursday February 26th the outer planet Neptune reaches a point in its orbit where it passes behind the Sun as we view this from Earth. Neptune, and the other outer planets, dwarf planets, or small solar system bodies, all eventually reach this position on the opposite side of the Sun known as solar conjunction.

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Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Jupiter at Opposition: 2015

Zooming in on Jupiter at Opposition   On Friday, January 6th, the outer giant planet Jupiter reaches the point in its orbit around the Sun that places the Earth in between Jupiter and the Sun. This is known as opposition, and opposition is an orbital position that applies to solar system objects (outer planets, dwarf planets, asteroids, comets, etc.) orbiting the Sun beyond the Earth’s orbit. An object at opposition will have approximately the same heliocentric longitude as the Earth’s heliocentric longitude – on Friday both planets will have a heliocentric longitude of about 137o.
   For those keeping track, last year Jupiter was at opposition on January 5th. An opposition of Jupiter occurs approximately every 13 months because both Earth and Jupiter are moving. After one Earth Revolution, an Earth year, the planet Earth will be where it was the previous year, at opposition with Jupiter. However Jupiter will not be there because it has moved during the past year as well. It will take the Earth that extra month or so to catch up with Jupiter. Earth moves 360o each year while Jupiter moves approximately 12o each Earth year.

Sunset Local Time

Sunset Local Time

   When an object is at opposition it rises at approximately the same time as local sunset and that same object at opposition sets at approximately the time of local sunrise. In other words an object at opposition will be up all night from sunrise to sunset.
   Picture our Moon at full phase and how it is directly opposite the Sun, with the Earth in between. The full Moon in effect is at opposition but we call it the full Moon instead. And like Jupiter at opposition, a full Moon rises at sunset, sets at sunrise and is visible all night. February’s full Moon, by the way, was on the 3rd.

   
Take a brief tour of the Jovian (Jupiter) system. Music by Dark Matter.
Live recording of music written by Richard Johnson. Video by me!

   
   
   
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Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

retipuJ sdrawkcaB A

Jupiter at 15 Day Intervals

Jupiter at 15 Day Intervals (8 November – 8 May)

   A Backwards Jupiter, or when the giant planet starts retrograde motion. Tuesday December 9th the largest planet in our solar system, Jupiter, begins its retrograde motion. Retrograde motion is an apparent motion that the outer planets, relative to the Earth, have. It is an apparent motion that looks as if the outer planet stops it normal direct motion to the east and reverses direction to the west. After a period of time the apparent westward motion ends and the planet resumes its normal orbital path to the east. Retrograde motion happens as the faster moving Earth catches up with and then passes by the outer planet. It is during this time that the backward apparent motion happens.
   The two inner planets also have retrograde motion but it is a result of their orbit around the Sun and not the Earth passing them by. For approximately one-half of their orbit they move east, from western elongation through superior conjunction to eastern elongation. Then at eastern elongation the inner planet starts moving westward through inferior conjunction to western elongation.
   Read a little more about retrograde motion in my February 2012 Scope on the Skies column, drawkcab planets, in Science Scope Magazine.
Click on graphic to see it full size.

Click on graphic to see it full size.

   Where is Jupiter now? Jupiter is a few degrees west from the star Regulus in Leo the Lion. Jupiter rises around midnight local and is visible above the horizon the remainder of the night.

   
   
   
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Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Saturn at Opposition

saturn-opposition-ani   Saturday 10 May at 1 pm CDT (18 UT) the outer planet Saturn reaches a point in its orbit around the Sun called opposition. This is an arrangement of Saturn, Earth, and the Sun that places the three in a pattern with the Earth in between Saturn and the Sun. Think full Moon and that is a good mental picture of Saturn, or any of the outer planets, at opposition. This animated graphic centered on the Sun shows the Sun, Earth, and Saturn from 15 March to 1 July at 1-day intervals. The faster orbital speed of the Earth allows the Earth to quickly catch up with and pass Saturn.

Click on graphic to see it full size.

Click on graphic to see it full size.

   At opposition, like with a full Moon, Saturn will rise at approximately local sunset time and Saturn will set at local sunrise time – visible above the horizon all night.
Finding Saturn is fairly easy especially if you follow the ‘old’ mnemonic “Follow the arc to Arcturus, then speed to Spica.” Once you have found Spica look down to the left for Saturn and up to the right for Mars and the Moon. On the 10th all four make a fairly straight diagonal line rising up from the eastern horizon toward higher above the southeast horizon.

Click here for Planet Oppositions 2005 to 2020.

   This is a short 4.5-minute video I made as part of a live musical performance called “Orbit” that was performed at the Gottleib Planetarium in Kansas City Missouri in May 2011. This is a piece from the much longer tour of the solar system performance and video and shows a fly-by of Saturn.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.