Jupiter Today | 09 August 2015 | The Conjunction of Io and Europa

Hello!

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.

At 0h UTC, Io begins the day in quad 3 moving west towards its western elongation.  Europa is in quad 4 moving east.  Ganymede starts the day on the west side of Jupiter in quad 3 moving west.  Callisto is passing through its eastern elongation and will spend the next few days in quad 2 moving west.

By 6h UTC, Io has passed through its western elongation and is now in quad 4 moving west.  Europa continues to move east in quad 4.

At 12h UTC, Io and Europa are passing behind Jupiter and moving into quad 1.  Ganymede is going through its western elongation and will be moving into quad 4 heading east.

At 18h UTC, Io and Europa are still very near one another from Earth's point of view and are both now in quad 1 heading east.  Ganymede is now firmly in quad 4 moving east.

By 0h UTC tomorrow, Io is very near its eastern elongation and will be moving into quad 2 heading west.  Europa continues in quad 1 moving east.  Ganymede is still in quad 4 moving east.  Callisto is now firmly in quad 2 heading west.

At 14:04 UTC, Europa moves through its apojove at a distance of 677,662.9 km.  At 14:18 UTC, Io moves through its perijove at a distance of 420040.1 km.

At 0h UTC, the position of Jupiter on Earths celestial sphere is RA 10h 06m 44.7s DEC +12d 32m 16.0s.  The phase angle (the angular separation between the Earth and Sun as seen from Jupiter) is 2.498 which is 0.136 degress less than yesterday.  The angular separation between Jupiter and the Sun is 13.38 degrees, which is 0.742 degress less than yesterday.  The distance between Jupiter and the Sun is 805,392,091 km.  This is 37,393 km further away than yesterday.  This results in a radial velocity between Jupiter and the Sun of 1,558.042 km/h, which is 3.583 km/h slower than yesterday.  The distance from Jupiter to Earth is 952,194,122 km, which is 569,181 km further away than yesterday.  This gives a radial velocity between Jupiter and the Earth of 23,715.875 km/h, which is 1,250.167 km/h slower than yesterday.

At 11:53 UTC, Europa moves behind Jupiter.  At 12:38 UTC, Io moves behind Jupiter.  At 15:12 UTC Io appears from the shadow of Jupiter.  Finally, at 15:23 UTC, Europa appears from the shadow of Jupiter.

As expected, there are some mutual events between Io and Europa.  From 03:59 to 04:13 UTC, Io occults Europa.  This is a 13.3 minute event with an impact parameter of 0.252 arc seconds.  From 04:41 to 04:57 UTC, Io eclipses Europa.  This 16.7 minute event has an impact parameter of 0.264 arc seconds.  The two moons now whip around the far side of Jupiter, and from 15:04 to 15:36 UTC Io occults Europa once again.  This is a 32.3 minute event (quite long for these moons) with an impact parameter of 0.066 arc seconds.  This is a near total occultation.

Orbital Ribbons for today:

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.