Jupiter Today | 08 August 2015 | Io Transits

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 starts today in quad 1 moving east.  Europa and Ganymede continue to appear near one another from Earth's point of view in quad 3 moving west.  Callisto spends one more day in quad 1.

By 6h UTC, Io is going past its eastern elongation and heading into quad 2 moving west.  Europa and Ganymede continue in quad 3 moving west.

At 12h UTC, Io is firmly in quad 2 moving west.  Europa is nearing its western elongation.

By 18h UTC, Io has transited Jupiter and is now in quad 3 moving west.  Europa is now past its western elongation and is now in quad 4 heading east.

At 0h UTC tomorrow, Io is firmly in quad 3 moving west.  Europa is in quad 4 heading east.  Ganymede continues in quad 3 moving west.  Callisto is at its eastern elongation and will be moving into quad 2 for the long trek westward towards Jupiter.

At 17:01 UTC, Io moves through its apojove (the furthest it will be from Jupiter in this orbit) at a distance of 432,494.2 km.

At 0h UTC, the position of Jupiter on Earth's celestial sphere is RA 10h 05m 55.3s and DEC +12d 36m 44.4s.  The phase angle today is 2.634 degrees, which is 0.134 degrees less than yesterday.  The angular distance between Jupiter and the Sun as seen from Earth is 14.122 degrees, which is 0.743 degress less than yesterday.  We're getting ever closer to Superior Conjunction on 26 August.  This distance between Jupiter and the Sun is 805,354,698 km, which is 37,479 km further away than yesterday.  This means that Jupiter appears to be moving radially away from the Sun at a velocity of 1,561.625 km/h, which is 7.125 km/h slower than yesterday.  The distance between Jupiter and the Earth today is 951,624,941 km, which is 599,185 km further away than yesterday.  Jupiter and Earth are moving away from one another at a velocity of 24,966.042 km/h, which is 1,247.291 km/h slower than yesterday.  This velocity will be at a minimum at the moment of Superior Conjunction.

From 15:22 to 17:41 UTC, Io transits Jupiter.  The shadow of Io follows from 15:40 to 17:58 UTC.

From 09:32 to 10:16 UTC, Ganymede occults Europa.  This is a 44.6 minute event with an impact parameter of 0.184 arc seconds.  A very nice occultation!  From 11:48 to 12:12 UTC, Ganymede eclipses Europa.  This is a 23.8 minute event with an impact parameter of 0.761 arc seconds.  So this is just a grazing occultation.  Both moons are pretty far from Jupiter, so if you can somehow deal with the glare of the Sun, this might be a great pair of mutual events.

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.