Posts Tagged ‘Pi’

03/14/2019 – Ephemeris – Happy Pi Day

March 14, 2019 Comments off

Ephemeris for Pi Day, Thursday, March 14th. Today the Sun will be up for 11 hours and 49 minutes, setting at 7:47, and it will rise tomorrow at 7:55. The Moon, at first quarter today, will set at 4:09 tomorrow morning.

Pi day: the first three digits of the mathematical constant π is 3.14 the ratio of a circle’s circumference to its diameter, so March 14th is Pi day. Why do we use the Greek letter pi? Pi is the first letter of the Greek word perimetros which means circumference. The first Pi Day was celebrated in 1988, organized by Larry Shaw at San Francisco’s Exploratorium. There are other lass known pi related days on the calendar. The fraction used in pi approximations is 22/7ths. So July 22nd is Pi Approximation Day. In many formulae π is multiplied by two, or 2π. 2π to two decimal places is 6.28, so it’s Two Pi Day or Tau (τ) Day, June 28th. So whether you like apple, cherry, or pumpkin, have a happy Pi day.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Check out for more information on pi.

Categories: Concepts, Ephemeris Program Tags: ,

3.1416 – 03/14/2016 – Ephemeris – When Jupiter hits your eye like a big pizza Pi

March 14, 2016 Comments off

Ephemeris for Pi Day 3/14, Monday, March 14th.  The Sun will rise at 7:56.  It’ll be up for 11 hours and 52 minutes, setting at 7:48.   The Moon, 1 day before first quarter, will set at 2:39 tomorrow morning.

We turn again to the giant planet Jupiter which is shining brightly in  the southeastern part of the sky in the early evening.  The first thing one notices in a small telescope are it’s four moons, generally in a straight line, which move back and forth each night.  Notice their plane.  It’s the same direction as the cloud bands are aligned.   Jupiter has a very small axial tilt, and its large satellites orbit pretty much over Jupiter’s equator.  Our Moon doesn’t behave that way, but that’s another story.  Jupiter rotates on its axis in a bit less than 10 hours, which whips its clouds into alternating bands of reddish-brown and cream color.  Also the rotation rate of these clouds lessens with increasing latitude.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Jupiter & Satellite Transits

Transits of Europa and Io across the face of Jupiter at 11 p.m. EDT March 14, 2016. The shadows of the moons are hard to see, but the satellites are even harder. Jupiter’s current cloud bands may not be as shown. Image created using Cartes du Ciel (Sky Charts).

Event EDT Universal Time
Date Time Date Time
Europa Transit Start March 14 09:26 PM March 15 01:26 AM
Europa Shadow Start March 14 09:45 PM March 15 01:45 AM
Io Shadow Start March 14 10:12 PM March 15 02:12 AM
Io Shadow Start March 14 10:21 PM March 15 02:21 AM
Europa Transit End March 15 12:12 AM March 15 04:12 AM
Io Transit End March 15 12:26 AM March 15 04:26 AM
Europa Shadow End March 15 12:33 AM March 15 04:33 AM
Io Shadow End March 15 12:36 AM March 15 04:36 AM

Jovian satellite data from Project Pluto.

Pi Day

Check this out:  Pi Day the NASA Way.

Answer to Friday’s Moon phase poser

Of the two representations of the Moon’s terminator last Friday, the Virtual Moon Atlas was the correct representation.

Categories: Ephemeris Program, Jupiter Tags: