S O L A R V I E W E RS O Y O U WA N T T O B U I L D Y O U R O W N …

W H AT I S T H E S A F E S T W AY T O V I E W T H E S U N ?

P I N H O L E V I E W E R S

photos from Life Magazine

B E C A R E F U L T O P U N C H A C L E A N P I N H O L E !

L A R G E , R O U G H H O L E

P I N H O L E

$ 1 S A F E S O L A R V I E W E R

http://richardsont.people.cofc.edu/safe_solar_folder/index.html

Created by T.R. Richardson (College of Charleston)

$ 1 S A F E S O L A R V I E W E R

http://richardsont.people.cofc.edu/safe_solar_folder/index.html

$ 1 S A F E S O L A R V I E W E R

http://richardsont.people.cofc.edu/safe_solar_folder/index.html

S O L A R P R O J E C T I O NI F Y O U H A V E B I N O C U L A R S O R A T E L E S C O P E

S O L A R P R O J E C T I O NI F Y O U H A V E B I N O C U L A R S O R A T E L E S C O P E

A N O L D S TA N D - B Y

S U N S P O T S !

S O L A R P R O J E C T I O NA N O L D S TA N D - B Y

PROS •Easy to set up!•Bright/large images if using large aperture.•No filter needed!

CONS •Possible for student to look into projector!•Requires lenses and tripod.

S U N F U N N E LR E A R - S C R E E N P R O J E C T I O N

This simple & inexpensive device makes it easy for many people to observe the Sun simultaneously — and safely!

Origin of the Sun Funnel: Amateur astronomers Gene Zajac and Chuck Bueter adapted an existing design for a 2003 Great Lakes Planetarium Association Conference workshop. The rear-screen projection material shown here is an idea borrowed from Bruce Hegerberg’s Sun Gun.

https://eclipse2017.nasa.gov/make-sun-funnel

from a talk by Richard Tresch Fienberg (AAS)

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Supplies & Tools

Red numbers correspond to items listed on the next two pages.

from a talk by Richard Tresch Fienberg (AAS)

Match the Eyepiece to Your Telescope What type of telescope? Refractor!

Eyepiece (no plastic; all metal & glass)

Using a Newtonian reflector or a catadioptric (mirror-lens) telescope is strongly discouraged, as concentrated sunlight can destroy such instruments’ secondary-mirror holders.

Objective (main lens, glass)

Photo: Explore Scientific

Star diagonal (no plastic; all metal & glass)

from a talk by Richard Tresch Fienberg (AAS)

Or, you can calculate the focal length of your telescope from its diameter (D) and focal ratio (f/ratio or f/number):

FLtelescope = Dtelescope × f/ratio

Example: For the 66-mm f/5.9 refractor shown on the previous page, FLtelescope = 66 mm × 5.9 = 389 mm (close enough; round-off error!)

Best eyepiece for a full-disk (~100 mm diameter) solar image:

FLeyepiece (mm) ≈ FLtelescope (mm) ÷ 43

(The derivation of this formula appears later in this document.)

Example: For the Galileoscope, a 50-mm f/10 refractor (FLtelescope = 500 mm), the eyepiece that will produce a full-disk solar image has a focal length of FLeyepiece = 500 ÷ 43 = 11.6 mm. There are many inexpensive 12.5-mm eyepieces available; any would make a good choice.

An eyepiece with a shorter focal length will produce a larger Sun image; an eyepiece with a longer focal length will produce a smaller Sun image.

from a talk by Richard Tresch Fienberg (AAS)

Telescope Eyepiece (FLtelescope) (FLeyepiece)

300 mm 7 mm 400 mm 9 mm 500 mm 12 mm 600 mm 14 mm 700 mm 16 mm 800 mm 19 mm 900 mm 21 mm 1000 mm 23 mm

Sample Pairs of Telescope & Eyepiece Focal Lengths for a Full-Disk Image of the Sun on the Sun Funnel

Don’t worry about getting the eyepiece focal length “exactly right.” Depending on what you have available or what you can buy cheaply, aim to get an eyepiece whose focal length is within ± 10% of the “ideal” value of FLtelescope ÷ 43.

from a talk by Richard Tresch Fienberg (AAS)

Add a Solar Shade to Your Sun Funnel

To improve the view on the Sun Funnel’s screen, it helps to get it out of direct sunlight. An easy way to do this is to make a “solar shade” out of a 16-by-20-inch piece of black foam board, available online or at your local art- or office-supply store. Cut a hole the same size as your telescope tube using an X-acto knife and slip the shade over the tube as shown in the photos here. Tip: Use your lens cap as a template for the hole, but cut the hole a little smaller than the inside diameter of the cap so that the board fits snugly around the tube and will stay where you put it.) from a talk by Richard Tresch Fienberg (AAS)

S U N F U N N E L

PROS •Easy to see•No touching! So no bumping or refocusing•No beam of light to intersect with student’s eye

CONS •May be tricky to find the right eyepiece•Make sure not to overheat your telescope•Not recommended for reflectors

B A A D E R S O L A R F I LT E R S

see astrosolar.com/en/ for instructions

S O L A R F I LT E R S

PROS •“Best” view• Easy to make/use

CONS •Can be tricky to view•Easy to bump telescope•Can’t use if scratched/broken.•Can overheat

S O M E W AY S T O V I E W T H E S U N : 1 . P I N H O L E 2 . S A F E S O L A R V I E W E R 3 . P R O J E C T O R 4 . S U N F U N N E L 5 . S O L A R F I LT E R

W E H AV E S O M E T I M E L E F T… L E T ’ S B U I L D O U R O W N V I E W E R S