Archive

Posts Tagged ‘Great American Eclipse’

08/14/2017 – Ephemeris – Safe ways to view the eclipse

August 14, 2017 1 comment

Ephemeris for Monday, August 14th. The Sun rises at 6:44. It’ll be up for 14 hours and 4 minutes, setting at 8:49. The Moon, at last quarter today, will rise at 12:46 tomorrow morning.

It is one week to the Great American Eclipse, next Monday August 21st. Whether you’re heading out to the path of totality, or staying here it is imperative that you view the Sun safely. Solar filters may be purchased from some reputable stores. But there are some unsafe solar filters being sold out there. Beware. Also never use eclipse glasses to view the Sun with binoculars. The concentrated sunlight coming out of the eyepiece will burn through the plastic of the solar filter in an instant. The best method is to project the Sun’s image with a pinhole in a box or place a mirror in an envelope with a quarter-inch or so hole in it, and project the Sun on the shady side of a building. There’s plenty of Internet links at http://www.gtastro.org.

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

Addendum

Two pinhole solar projection methods

Two pinhole solar projection methods. Credit NASA.

The danger at looking at the Sun without proper filter

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

 

07/25/2017 – Ephemeris – Why do solar eclipses happen?

July 25, 2017 1 comment

Ephemeris for Tuesday, July 25th. The Sun rises at 6:21. It’ll be up for 14 hours and 54 minutes, setting at 9:15. The Moon, 2 days past new, will set at 10:48 this evening.

We have a day less than 4 weeks before the Great American Total Solar Eclipse on August 21st will occur. Solar eclipses occur at new moon, when the moon is aligned so its shadow falls on the Earth. It doesn’t happen every new moon because the Moon is a long ways away, and its orbit is tipped some 5 degrees from the Earth’s orbit of the Sun, so usually the Moon is north or south of the Sun at new moon. About one in every 6 new moons produces an eclipse. They occur when the Moon is near the crossing point of the two orbital planes, called nodes. The point where the Moon is passing the node in northward direction is called the ascending node, and 180 degrees around the orbit there is the descending node, but you have to be in the right spot to see an eclipse.

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

Addendum

Anatomy of an eclipse

What happens to create a total solar eclipse. Note the Sun’ distance as being 400 times the distance of the Moon. The Sun is also 400 times the Moon’s diameter, so they appear nearly the same size from the Earth. Credit NASA and the Eclipse2017.NASA.gov website.