Jupiter's and Saturn's Moons always lose a day!

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Jupiter's and Saturn's Moons always lose a day!

Postby astrojohn » Fri Jul 18, 2014 2:24 am

Why do you draw the moons charts for Jupiter and Saturn with a day missing? For example, in the August
issue there is only data for 30 days (since there are 31 'midnights'). The dates are adjacent to the lines,
which represent midnight - but is that midnight at the start or finish of that date? If it's the start of the !st, then the 31st is missing.
Why don't you do it the way Sky and Telescope do (surely it's not copyright) - they put the date in the
middle of each day space, that way there is no confusion AND we get a full month of data!

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Re: Jupiter's and Saturn's Moons always lose a day!

Postby Admin » Tue Jul 22, 2014 1:56 pm

In the moon charts for Jupiter and Saturn, each date represents a 24hr day. The moment in clock time when one date moves to the next is midnight; thus 23:59:59 UT is the last second of 31 July and 00:00:00 UT is the first second of 1 August. Therefore the line adjacent to each date in our Jupiter and Saturn moon diagrams represents the start of that date. From the September issue onwards we will be adding the evening of the last date of the month to the diagram, which is currently missing. Thanks for pointing this out John.

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