Solstice at 17:48 on 2009-12-21

Jupiter is following the Moon down to the horizon

Jupiter is following the Moon at present, and this sight prompted me to dig up some of my old astronomical Web pages and spreadsheets. Below are some highlights. The Web site is available on this server in the kepler directory.

Screenshot of the solstice spreadsheet with 2009 data showing

My Solstice spreadsheet based on Jean Meeus’ routines from his Astronomical Algorithms is predicting the instant of the winter solstice for 2009 within one minute of the USNO prediction. Not bad for a simple spreadsheet.

Screenshot of spreadsheet that calculates and displays the altitude of the sun and moon for a given position on earth and instant

You can see how short the day is on the 21st by looking at a screen grab from my illustrative spreadsheet above. Click on the thumbnail to get the full resolution grab. You can download the spreadsheet in XLS (MS Excel) format. The Sun and Moon altitude spreadsheet will work in OpenOffice 3.1 but you can’t save in ODS format, if you do the graphic stops being hotlinked to the calculations.

I’ll try to sort that out!

             sun       c twi    n twi     a twi     moon
date        r    s   b    e    b    e    b    e     r    s
------------------------------------------------------------
20091216  0813 1554 0732 1635 0647 1720 0605 1801  0832 1535
20091217  0814 1554 0732 1635 0648 1720 0606 1802  0916 1637
20091218  0814 1554 0733 1636 0648 1720 0607 1802  0949 1746
20091219  0815 1555 0734 1636 0649 1721 0607 1802  1012 1856
20091220  0815 1555 0734 1636 0650 1721 0608 1803  1031 2007
20091221  0816 1556 0735 1637 0650 1722 0608 1803  1046 2117
20091222  0817 1556 0735 1637 0651 1722 0609 1804  1100 2226
20091223  0817 1557 0736 1638 0651 1723 0609 1804  1112 2336
20091224  0817 1557 0736 1639 0651 1723 0610 1805  1125 ----
20091225  0818 1558 0737 1639 0652 1724 0610 1806  1138 0047

You can calculate the sun rise and set times, the twilights and the times of moonrise using my javascript sunrise calculator. This javascript uses a slightly more robust algorithm than the trial and improvement system that Meeus uses, and so it will work closer to the Arctic Circle.

I still get a number of inquiries about my approximate astronomical positions web pages. They are hosted on bodmas, but there is a mirror that has slightly out of date pages on that has a higher Google rank!

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