Jupiter Today | 26 August 2015 | Superior Conjunction!

Hello! Today is a special day in that it is the day of Superior Conjunction.  SC is when a planet is in alignment with the Sun with respect to another planet.  Mercury and Venus have both Inferior and Superior Conjunctions as seen from Earth, but all of the planets with orbits larger than Earth have only Superior Conjunctions.  SC is also the time and place where the two bodies end moving away from one another and begin moving toward one another.  This motion will continue until Opposition.

JUPITER TODAY is a daily blog about the dynamic Jupiter system for the purpose of monitoring activity.

We start with the overall view of activity with the Jupiter system, showing the orbits of the four Galilean moons:

This is a view of the Jupiter system looking down on it.  Following the blue line to the left is the line of sight to Earth, while following the gray line to the left is the line of sight to the Sun.  The orbits of the four Galilean moons are shown.  The large dots indicate the position of each moon at 0h, 6h, 12h, 18h, and 24h (0h the next day) UTC for this date.  From this point of view, the moons revolve around Jupiter in a counter-clockwise motion.  For more information about this graphic, see the post from 30 July 2015.

Jupiter continues to move towards Superior Conjunction on 26 August.  These images blow me away they are so incredibly beautiful.  Here's the current SOHO image showing the steady progress:

The graph below shows the positions of the four Galilean moons over the next 24 hours as seen from Earth.  The curved lines show the path of each moon through time.  The dark band in the center is Jupiter.  The x-axis is the distance, in arc seconds, from the center of Jupiter:

At 0h UTC, Io has just gone through its eastern elongation and is now in quad 2 moving west.  Europa starts the day in quad 3 moving west.  Ganymede spends all day in quad 1 heading east.  Callisto has settled into quad 2 moving west and will be there the next few days.

By 6h UTC, Io is now firmly in quad 2 heading west.  Europa is near western elongation and will be moving into quad 4 heading east.

At 12h UTC, Io has transited Jupiter and is now firmly in quad 3 moving west.  Europa has passed its western elongation and is now in quad 4 moving east.

At 18h UTC, Io is near its western elongation and will be moving into quad 4 heading east.

By 0h UTC tomorrow, Io is firmly in quad 4 moving east.  Europa is also in quad 4 heading east.  Ganymede continues in quad 1 moving east.  Callisto is out there nearly 2 million km from Jupiter orbiting in quad 2 heading west.

The position of Jupiter on Earth's celestial sphere today is RA 10h 20m 49.4s, DEC +11d 14m 21.3s.  The phase angle is 0.208 degrees, which is 0.107 degrees less than yesterday.  The angle between Jupiter and the Sun as seen from Earth is 1.109 degrees, which is 0.568 degress less than yesterday.  At the time of Superior Conjunction (about 22h UTC) the separation angle will be at a minimum at 0.873 degrees.  The distance between Jupiter and the Sun is 806,019,276 km, which is 36,484 km further apart than yesterday.  Jupiter and the Sun are moving away from one another at a velocity of 1,520.167 km/h, which is 1.75 km/h slower than yesterday.  The distance between Jupiter and Earth is 957,186,157 km, which is 46,548 km greater than yesterday.  Jupiter and Earth are moving away from one another at a velocity of 1,939.5 km/h, which is 1,288.083 km/h slower than yesterday.  The distance at SC is 957,201,696 km.

From 08:26 to 10:45 UTC, Io transits Jupiter.  Io's shadow also transits Jupiter at nearly the same time interval from 08:27 to 10:45 UTC.

Now the Glorious Orbital Ribbons for this Glorious Superior Conjunction:

Jupiter is so near Superior Conjunction (taking place at 22:00 UTC on 26 August 2015) that photography and other data collection isn't practical.  We'll have to wait about a months after SC to start viewing the Jupiter system again.

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Please send me your feedback, comments, and questions to jupitertoday AT gmail DOT com or the comments section of this blog.

With my gratitude, the data used to create the orbit plots and ribbons was supplied by the JPL Horizons website.  The graphics showing the location of the four moons as seen from Earth are via 'Jupiter Viewer 2.8'.  Jupiter-Satellite and Satellite mutual events data is supplied from IMCEE.

Until tomorrow, I bid you Peace.