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. Here's the current SOHO image showing the steady progress:
At 0h UTC, Io begins the day in quad 2 moving west. Europa is in quad 3 also moving west. Ganymede spends all day moving east in quad 1. Callisto spends all day in quad 4 moving east towards Jupiter.
By 6h UTC, Io is about to begin its transit of Jupiter. Europa is close to its western elongation and will be moving into quad 4 heading east.
At 06:51 UTC, Io goes through an apojove (the furthest it will be from Jupiter in this orbit) at a distance of 423,487.7 km.
At 0h UTC, the position of Jupiter is RA 10h 15m 01.1s, DEC +11d 46m 48.1s. The phase angle today is 1.12 degrees, which is 0.138 degrees less than yesterday. The angular separation between Jupiter and the Sun is 5.97 degrees, which is 0.738 degrees less than yesterday. The distance between Jupiter and the Sun is 805,762,860 km, which is 36,814 km further away than yesterday. Jupiter and the Sun are moving apart at a velocity of 1,533.917 km/h, which is 0.958 km/h slower than yesterday. Wobble, wobble, wobble. The distance between Jupiter and the Earth is 956,210,424 km, which is 263,205 km further apart than yesterday. Jupiter and Earth are moving away from one another at a velocity of 10,966.875 km/h, which is 1,286.917 km/h slower than yesterday. So while we're moving away from Jupiter, we are decelerating at an ever larger amount. It's very similar to going over a very large speed bump.
From 06:25 to 08:43, Io transits Jupiter. From 06:32 to 08:50, the shadow of Io transits Jupiter.
From 21:22 to 22:00 UTC, Io occults Europa. This is a 38.3 minute event with an impact parameter of 0.305 arc seconds. A graze. From 21:54 to 23:21 UTC, Io eclipses Europa. This long 87.1 minute event has an impact parameter of 0.093 arc seconds, which is a pretty nice eclipse. From 23:46 to 01:21 UTC tomorrow, Io eclipses Europa once again. This is also very long ad deep at 94.7 minutes with an impact parameter of 0.081 arc seconds. I can't figure out the motions such that we'd see two eclipses back to back. I'll try to figure that out and report on in over the next couple days.
And now 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.
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