Archive for August 21, 2017

08/21/2017 – Ephemeris – Today’s the day of the solar eclipse!

August 21, 2017 1 comment

Ephemeris for Monday, August 21st. The Sun rises at 6:52. It’ll be up for 13 hours and 45 minutes, setting at 8:37. The Moon is new today, and won’t be visible, except when it’s covering the Sun.

This is it! Later today, we will see, clouds willing, the Great American Solar Eclipse. The Grand Traverse Astronomical Society and the Sleeping Bear Dunes National Lakeshore will host an eclipse watch at the Dachow farm on M-22 at Port Oneida Road. There will be telescopes to view the eclipse and one to project the eclipse on a screen. The first 100 or so visitors can get a pair of eclipse glasses. The times, if you are in the Grand Traverse area, say near Traverse City and Interlochen, are these: The eclipse starts at a couple of minutes before 1 p.m., The maximum eclipse will be at 2:20 when nearly 75% of the Sun will be covered by the Moon. The eclipse will end about 3:40 p.m. These times are within a few minutes for other locations in northern Michigan.

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


Maximum eclipse in Traverse City

What the maximum eclipse would look like with proper filtering in the Grand Traverse area. Created using Stellarium.

Pinhole projection

Pinhole projection is the simplest way to project the Sun’s image.
A long box can be used to project the image inside. The diameter of the pin hole is a compromise between sharpness and brightness of the image.
The farther the image is projected the larger it is.
The throw of the image can be increased by using a mirror masked with a quarter of a inch or larger hole and sending the image 10 or more feet away.

Binocular projection

I’m demonstrating using binoculars to project the Sun. Photo by Bea Farrell (granddaughter).

Tree provided pinholes

Let nature provide the pinholes.
Sit under in the shade.
Stay cool,
And watch the Sun’s images on the ground.

The danger at looking at the Sun without proper filter

The danger with looking at the Sun without proper filter. Credit: University of Waterloo.