Steve’s Virtual Planet

Planning on Venus - pt2

In part one of this post, I described the basic use of Sky View Cafe for planning your viewing of Venus. I hope you’ve already had a chance to see our sister planet off in the west after sunset. It’s been a lot fun showing people how Venus goes through phases, something that most folks don’t know!

In this post, I’ll describe the use of an ephemeris, which by definition, is a chart or table of times at a regular interval with the positions of objects in the sky.

Our fine friends at the Jet Propulsion Laboratory have been generating these data sets for some time, as it turns out. This data has been published on the AstroPixels website in a multi-part table where you can get all the fine details for Venus for each day. You can use this table to plan your sighting of Venus in advance (AstroPixels has charts for the sun, moon and the other planets as well ).  The columns in the list give you the main numbers - date, RA/Dec, Visual Magnitude and phase Illumination.

Once you get the feel of the empheris data layout, the next step is to get the details for Venus’ position for the day you want. You can find the azimuth and altitude numbers for each hour & minute of the day using the SkyViewCafe Sky tab. You can work the time setting back and forth, then place the pointer over Venus to get the Azimuth and Altitude on the info band at the bottom. Then, you can determine where to look by the compass bearing, then the angle up from the horizon.

Finally, I suggest making yourself a planning sheet. You can print the web page(s) but that tends to produce a lot of paper. Better yet, you can copy and paste the text from the web page into a work document. If you use the mouse to select a portion of a table, then copy, this places the text into a clipboard space you can paste into a new document of the work sheet. You can clean up the page by reducing the font size and expanding the margins so it all fits. When you have a nice neat list of items in your table, print it out as a field reference.

Happy “plan it” hunting!!