Jupiter Today | 12 August 2015 | Perseids

Hello!

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

Hey make sure to go out and take a look at a few (or more) Perseid meteors.  Go out after midnight on the evening/morning of the 12th/13th and just look up.  If you stand out and look for 15 minutes, I can pretty much guarantee you'll see one.  They'll be appearing to come from the east (from the constellation Perseus).  They are pretty fast, usually white in color, and can leave some pretty nice trails.

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 2 moving west.  Europa is in quad 3 moving west going towards its western elongation.  Ganymede is in quad 1 moving east all day today.  Callisto is in quad 2 moving west all day long.

By 6h UTC, Io is transiting Jupiter and moving into quad 3 moving west.  Europa is at western elongation and moving into quad 4.

At 12h UTC, Io is firmly in quad 3 heading west and Europa is firmly in quad 4 heading east.

By 18h UTC, Io has gone past its western elongation and is now in quad 4 heading east.  Europa is going to be moving behind Jupiter soon in quad 4.

At 0h UTC tomorrow, Io is in quad 4 moving east and will be going behind Jupiter soon.  Europa is also with Io moving behind Jupiter.  Ganymede is nearing its eastern elongation in quad 1.  Callisto spends its last few hours in quad 2 before it transits Jupiter and moves into quad 3 early tomorrow.

At 05:10 UTC, Io goes through its apojove at a distance of 423,487.1 km.

At 0h UTC, the position of Jupiter on Earth's celestial sphere is RA 10h 09m 13.2s, DEC +12d 18m 45.6s.  The phase angle today is 2.086 degrees, which is 0.138 degrees less than yesterday.  The angular separation between Jupiter and the Sun is 11.153 degrees, which is 0.742 degress less than yesterday.  The distance between Jupiter and the Sun is 805,503,953 km, which is 37,376 km further away than yesterday.  This translates to a radial velocity of 1,553.167 km/h, which is 0.708 km/h slower than yesterday.  The distance between Jupiter and Earth today is 953,720,434 km, which is 478,471 km further away than yesterday.  This makes Jupiter appear to be moving radially away from Earth at a velocity of 19,936.291 km/h, which is 1,264.417 km/h slower than yesterday.

From 04:23 to 06:41 UTC, Io transits Jupiter.  From 04:38 to 06:56 UTC, the shadow of Io transits Jupiter.

From 17:34 to 17:50 UTC, Io occults Europa.  This 15.9 minute event has an impact parameter of 0.257 arc seconds.  From 18:10 to 18:31 UTC, Io eclipses Europa.  This is a 20.6 minute event with an impact parameter of 0.203 arc seconds.

And finally, the glorious Orbital Ribbons:

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.