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Posts Tagged ‘Pinhole projection’

06/09/2021 – Ephemeris – The Sun will be partially eclipsed as it rises tomorrow morning

June 9, 2021 Comments off

I’ll review the planets tomorrow. However, tomorrow morning, if it’s clear down to the northeastern horizon, we will get to observe, safely, the Sun rise while being in eclipse. Here’s today’s program:

This is Ephemeris for Wednesday, June 9th. Today the Sun will be up for 15 hours and 30 minutes, setting at 9:27, and it will rise tomorrow at 5:57. The Moon, 1 day before new today, will rise with the Sun at 5:57 tomorrow morning.

The Moon rising with the Sun will also be eclipsing the Sun, so the Sun will have a big bite taken out of its left side as it rises tomorrow. We will be witnessing the last 40 some minutes of the eclipse as the Sun rises. The Sun is dangerous to look at. If you have eclipse glasses from the 2017 eclipse, use those. Otherwise, use pinhole projection from one side of a box to the opposite side. The longer the box, the bigger and dimmer the image. If using a corrugated cardboard box, make a big hole at the pinhole end, cover it with a thin piece of cardboard or aluminum foil. Punch several holes of various sizes spaced out on that end to project multiple images of the Sun, so you can choose the best to view. Good luck!

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

Addendum

Two pinhole solar projection methods

 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 pinhole is a compromise between sharpness and brightness of the image. The farther the image is projected, the larger and dimmer it is. The throw of the image can be increased by using a mirror masked with a quarter of an inch or larger hole and sending the image 10 or more feet away. Credit NASA.

Eclipsed Sun rising

A Stellarium creation of what the eclipsed Sun would appear about 10 minutes after rising as seen from the Traverse City/Interlochen area.

The visibility map for the June 10, 2021 annular solar eclipse

The visibility map for the June 10, 2021 annular solar eclipse. In an annular eclipse, the Moon is too far away and appears too small to cover the face of the Sun. So, at maximum, a ring of bright Sun surrounds the Moon. It’s sometimes called a ring of fire. For locations within the big floppy figure 8, the eclipse either ends near sunrise (bottom lobe) or starts near sunset (top lobe). The double line with the ellipses in it is the path of where the ring is visible, the path of annularity. Locations within the grid on the right will see a partial eclipse. Credit: NASA/GSFC/Fred Espenak, adapted from https://eclipse.gsfc.nasa.gov/SEplot/SEplot2001/SE2021Jun10A.GIF

 

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.

 

05/17/2012 – Ephemeris – A safe way to view this Sunday’s solar eclipse

May 17, 2012 Comments off

Ephemeris for Thursday, May 17th.  Today the sun will be up for 14 hours and 54 minutes, setting at 9:06.   The moon, 3 days before new, will rise at 4:44 tomorrow morning.  Tomorrow the sun will rise at 6:10.

Lets talk about a safe viewing method for viewing the sun, for Sunday’s solar eclipse, which starts about 8:19 p.m.  Never look directly at the sun, eclipse or no.  Pinhole projection is a cool method to watch the eclipse without hurting your eyes.  Get a cardboard box, the longer the better.  On one narrow end poke a hole, no larger than an 8th of an inch in diameter.  You can poke several holes an inch apart of varying sizes to get multiple images of the sun of different brightnesses and sharpness.  On the inside of the other end paste a piece of white paper.  Point the holey end at the sun and its image will be projected on the white sheet.  Tomorrow I’ll tell you where to go to get the best view of the eclipse.

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

Addendum

There’s more information on my blog here.

Pinhole projection:

Pinhole Projection of the sun.

Pinhole Projection of the sun.

Note the brightness of the sun was augmented and moon shadow added to give an idea what the solar image would look like.  The box is 39 inches long.  it gives an image 1/3 of an inch in diameter.