Planatery Ephemerides

Sometimes you look at a chart and see that a planet is retrograde and wonder when it started its backward motion.  Or you may see a planet at the beginning or end of a sign and wonder about the exact moment of crossing.  The Planetary Cycles and Sign Ingresses files at astro.com are an excellent source for gaining quick, precise answers to these questions.  All it takes is a few clicks and in less than 30 seconds you can download the file you need to see how time was flowing before and after the moment you are studying in a chart.

Planetary ephemeris files are a bit different from basic yearly ephemerides.  Nowadays there are many basic yearly ephemerides available for free on the internet.  Some sites even have the files as web pages that do not require downloading.  While the yearly ephemeride files at astro.com include the midnight Universal Time (aka GMT) positions of all planets and the north node for every day of the year, the planetary files focus on the exact Universal Times for points of interest in the cycles of individual bodies.  So instead of just knowing Jupiter entered Scorpio sometime after midnight UT on Oct 10, 2017 you can see the exact moment of ingress.

A few posts back, in Microscope to River, I included screenshots from the 2017 astro.com ephemeris.  Today I present a series of highlighted screenshots showing how to navigate to the ephemeris and download a file for Jupiter.  You need the Adobe pdf app to open and read the downloaded files, or another app to read pdf files may work. 

The first image shows where to click on the astro.com home page.  After selecting the Astrology drop down menu scroll down and click on 9000 Years Ephemeris.  Yes, 9000 years.  Amazing the wealth of perfectly good data people give away for absolutely nothing.  This form of generosity is a constant source of inspiration for me..

Scroll down past the few explanatory paragraphs and the list of centuries and select Planetary Cycles and Ingresses.  From there you can pick your planet and the time period you are interested in. 

For current Jupiter info you want the 1600 - 2100 file under the heading  Jupiter cycle data.  The 4th image shows where to click.  Unless your device is slow it should not take more than a fraction of a minute to download.  Since the file begins at 1600 you have to scroll way down to get to 2017.

The last ephemeris image shows Evening set highlighted on Oct 13 in green and Morning rise on Nov 8 in yellow.  Just above the green line you can see that Jupiter entered Scorpio  Oct 10 at 13:20 UT.  Raleigh converts UT to eastern time by subtracting 5 hours (8:20am) and then adding an hour for daylight savings, giving 9:20 am.  We check our balance of time by requestiing a chart for Oct 10, 9:21am Raleigh to see if it shows Jupiter at 00Scorpio.

You can see Jupiter at 00Scorpio in the chart that wraps up this post.  It was a bit above the eastern horizon in Raleigh, but of course invisible because of Apollo's many arrows.