Planetary charts

Here some charts which show the elongations of the bright planets – Mercury, Venus, Mars, Jupiter and Saturn – from 2018 until 2050.

Planetary Elongation Charts (2018 – 2050)

This is a PDF with a size of ~3MB.

There are plenty of apps and software which can show where the planets are at a given place, date and time.  However, it isn’t so easy to visualise at glance what the planets are doing over longer periods or when two planets will be in conjunction.

I first saw these elongation charts in the 1980s in a book called Amateur Astronomer by Antonín Rükl.  Those charts covered the period 1980 to 2000 (a final year which seemed ridiculously far in the future at the time!)  During my PhD I learned how to code in LaTeX and later, in PSTricks.  One Christmas holiday I decided to see if I could make a chart like those in Rükl’s book.  I changed my version slightly.  The colour scheme for northern and southern hemisphere constellations is inverted and the “unobservable” zone near the Sun is more realistic for Northumberland.  Making a chart for the next year became a Christmas tradition.  I used to get the data from NASA, import it into Excel and then use a number of macros to get it into a format where PSTricks could handle it.  In all it took about 5-6 hours to make a charts.  Eventually I discovered AstroExcel and was able to automate much of the process (now a chart takes about 30 minutes to prepare).  At this stage I was able to generate charts all the way out to 2050 (a ridiculous futuristic date).

Examples for the first four charts of individual years are shown below.

Briefly, the charts show you whether a planet is in the evening sky (after sunset) or in the morning sky (before sunrise).  The chart runs from January 1st at the top to December 31st at the bottom.  You see which constellations the planet is in throughout the year.  Intersections correspond to planetary conjunctions (when a planet overtakes another in the sky).  The elongation – the angular distance between the planet and the Sun – can also be seen.  The position of the Sun runs down the middle of the chart.