Where is Jupiter?

   For the past several months the outer planets Jupiter and Saturn have been the brightly shining ‘evening stars’ over the western horizon at sunset. They have recently been joined by the inner planet Venus, but at the same time as Venus has become more prominent each evening Jupiter and Saturn have been setting earlier as they gradually move closer to the horizon at sunset.

   And now Jupiter is no longer in the ‘picture’. So what happened to Jupiter, and will soon happen to Saturn? All solar system objects orbiting the Sun beyond Earth’s orbit move at a slower pace around the Sun than the Earth. The Sun has an apparent motion toward the east which is the same as the Earth’s actual motion. So what happens is that over time the Sun catches up with Jupiter, then Saturn. Eventually the Sun passes them and the planets become visible in the morning skies rising ahead of the Sun.

   At some point along their respective orbital path they will be on the opposite of the Sun from the Earth. This is known as solar conjunction, and that is where Jupiter will officially be on Friday December 27th.

   
   
   

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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Neptune at Eastern Quadrature

   Sunday November 29th the position of the planet Neptune with respect to the Earth and the Sun places this ringed planet at what is called eastern quadrature. Neptune is at a 90 degree angle from the Earth – think first quarter Moon as that is a fair comparison of the relative positions. At this position Neptune follows the Sun across the sky from east to west as the Earth is rotating, meaning that Neptune rises after the Sun and sets after the Sun.

   Where is Neptune now? The 8th planet from the Sun is currently within the constellation of Aquarius the Water Bearer and has recently completed its retrograde motion (November 18th).

   
   
   
   This is a 1 minute clip from a video I made showing Neptune and some of its moons as viewed from the Voyager 2 spacecraft. This clip is from a longer video of a tour of the solar system and was part of a live musical performance called “Orbit”. The performances were done in May 2011 at the Gottleib Planetarium in Science City at Union Station in Kansas City MO.

   
   
   
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.

Mars-Mercury Close Conjunction

22apr-bino   Wednesday evening April 22nd at sunset the inner planet Mercury and the outer planet Mars will be within 1-2o from each other as they set over the western horizon. The two should make for a nice view with binoculars as this graphic shows. Actually the two will be close to each other for the next several evenings. However Mars is setting earlier each night while Mercury is moving eastward away from the Sun and Mars. Compare the the relative orbital speeds: Mercury moves around 4o each day while Mars less than 1o. For another comparison look at their relative brightness. Mars has an apparent magnitude of 1.42 compared with the -1.1 for Mercury.

   Viewing the two planets may be a challenge as they are both low above the western horizon at local time for sunset.

   
   
   
   
   
   
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 No Longer Backing Up

   Well that’s a relief!

July 22nd to December 22nd :  Uranus at 30-day intervals

July 22nd to December 22nd : Uranus at 30-day intervals


   Monday December 22nd the outer planet Uranus ends its retrograde motion and resumes its eastward, or direct motion. Uranus begun this current retrograde motion last July 22nd. Retrograde motion is an apparent motion to the west that any outer planet relative to the Earth appears to do whenever the faster moving Earth passes by. Sort of like passing a car on the highway. You know both vehicles are moving in the same direction but from your perspective it could appear that the other car is moving backward as you go by. Regardless, retrograde motion for the outer planets happens at regular intervals as the Earth pass each one. It is always more than a year and always a little further to the east when the retrograde motion begins each time. This is because the outer planet is also moving eastward.

   
   
   
[centup]
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.

Mars at East Quadrature

orbital-positions   Saturday 19 July at 6 UT (1 CDT) the position of the planet Mars, with respect to the Earth and the Sun, places this planet at what is called eastern quadrature. At that orbital position Mars, and actually any outer planet, is at a 90 degree angle from the Earth as this graphic shows, and the banner graphic at the top of the page shows. Think first quarter Moon as that is a fair comparison of the relative positions of Earth, Sun, and Mars. At this position Mars follows the Sun across the sky from east to west as the Earth is rotating, meaning that Mars rises after the Sun and then sets after the Sun.

   This is a short video clip about Mars from a much longer video that I made as part of a live musical performance called “Orbit” at the Gottleib Planetarium in Kansas City Missouri during May 2011.

   
   
   
[centup]
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 West Quadrature

orbital-positions   Wednesday 28 May the position of the planet Neptune with respect to the Earth and the Sun places this ringed planet at what is called western quadrature. At that orbital position Neptune, and actually any outer planet, is at a 90 degree angle from us as this graphic shows. Think third quarter Moon as that is a fair comparison of the relative positions. At this position Neptune leads the Sun across the sky from east to west as the Earth is rotating, meaning that Neptune rises before the Sun and also sets before the Sun.
   

   This is a short video clip from a much longer video that I made as part of a live musical performance called “Orbit” at the Gottleib Planetarium in Kansas City Missouri during May 2011.

   
   
   
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.

Mars Ends Retrograde Motion

Click on graphic to see it full size.

Click on graphic to see it full size.

   Since the first of this past March the ‘red planet’ (love saying that!!) Mars has been moving in retrograde near the star Spica in Virgo. Retrograde, or retrograde motion, is an apparent reversal of an outer planet or dwarf planet’s regular orbital motion eastward around the Sun – as viewed from Earth. On Wednesday 21 May Mars ends its retrograde motion and resumes its regular or direct motion (eastward). Mars is also recently past opposition in April and so it is still near its maximum apparent magnitude (brightness) of -0.75. Nearby, for comparison, is the 3rd magnitude star Porrima.
Read more about the retrograde motion of Mars in a previous blog.

   
   
   
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.