2012 viewing prospects for May Solar Eclipse and June ... · PDF fileHow often do Venus transits occur? ... 1882 2012 1874 1639 1769 1761 How many Venus transits have been seen? •The

Observing Prospects for

May 20, 2012 Partial Solar Eclipse

and

June 5, 2012 Transit of Venus

Warning #1

Warning! NEVER look at the Sun directly through a telescope– you could be blinded.

Only use filters from reputable suppliers intended for solarobserving.

Do not assume that a filter which makes the Sun look dark issafe to look through: it may let through infra-red and/or UV.

St Louis Solar EclipsesBetween 1700 and 2100AD, there are 153 solar

eclipses are visible from St Louis.

Of these 153 eclipses, one is total, three are annularand the rest are partial.

That is an average of 3.8 eclipses per decade.

Reference: http://eclipse.astronomie.info/sofi/inter/inter/U386902.HTM

Recent Solar Eclipses• Does it seem like a long time has passed since our last solar

eclipse?• If you count the 1% eclipse of 2005, it has been 7 years!• 10 years if you go back to 2002 for a significant eclipse.

The next solar eclipse willoccur on Sunday May 20, 2012

Sony Super 8 Camcorder with 2X Tele

May 20, 2012 Partial Solar EclipseIn St. Louis, the moon will block 53% of the sun. The sun sets only 40 minutesafter the eclipse begins.

•Starts 7:25pm

•Alt=7.5 deg, Az=296 deg

•Sunset 8:05pm

St Louis at Sunset

May 20, 2012 Partial Solar EclipseThe path of the Annular Eclipse runs from western Texas to Asia

2012 Partial Solar Eclipse1994 was the last time an Annular Eclipse was visible from St. Louis

VHS Video camera with 60mm telescope

2012 Partial Solar Eclipse• Plan to observe from a location with a good western horizon

so you can observe the sun setting while it is still 53%eclipsed.

• Photos below taken from the Chesterfield Mall parking lot• The last 4 images below are “unfiltered”


Future Solar Eclipses• October 23, 2014 the moon will block 39% of the

Sun and once again the sun will set while eclipsed.This eclipse starts with the sun only 16 degrees abovethe horizon and the sun sets 90 minutes later with30% of the sun blocked.

Partial Solar Eclipse begins 5:40pm

Azimuth=311 degrees

Altitude=16 degrees

Maximum eclipse: 6:47pm

50.483%,

Eclipse at Sunset: 7:10pm

40.4%,

Future Solar Eclipses• August 21, 2017, parts of St. Louis are in the path for a Total

Solar Eclipse• The only time during the 400-year period from 1700-2100!• The path for observing totality is very narrow. You must be in

the path to see it

Future Solar Eclipses• The duration of totality is short as seen from South

St. Louis City, where total phase only lasts 39seconds. However, if you travel south to thecenterline, near Desoto or St Clair, MO the totalitywill last 2m 40s.

Future Solar Eclipses• Totality begins at 2:17pm when the sun is 65 degrees high• Look for the moon's shadow approaching from the southwest,

look for eerily cast shadows from poles or buildings.• Look for small pin-hole images of the solar crescent projected

through leaves in trees. The photo below was taken in 1994and show dozens of tiny crescents projected through the leavesof a tree.

12:50pm Partial Eclipse begins:

2:17:41pm Totality begins

2:18:20pm Totality ends

3:44pm Partial Eclipse ends

Future Solar EclipsesOne of the most fabulous sites in nature!

Transit of Venus

June 5, 2012

June 5, 2012What locations can see the transit?

Most of the Earth except eastern S. America andwestern Africa (red area)

121 ½ 121 ½ 105 ½105 ½

8888 8

How often do Venus transits occur?

•Venus transits occur in pairs spaced 8 years apart separatedby 105 and 121 year cycles.

•The ½ year difference means that transits alternate betweenDecember and June

2117

2125

2004

20121882

1874

17691639

1761

How many Venus transits have been seen?

•The first transit was seen in 1639. The 2012 transit will be onlythe 7th witnessed!•The next one visible from St. Louis will be 2125

** Visible from St. Louis

**

**

**** ** **

JuneJune DecDecDec

Why are Venus transits so rare?

Sun

Venus

Earth

Transits can only occur where the orbital planes ofEarth and Venus cross

When the Earth and Venus are not at these locations,Venus passes above or below the Sun

Why are Venus transits so rare?

Sun

Venus

Earth

June

Dec

Venus TransitDec 6, 1882

The transit of Venus, 1882

• America was still awild place in 1882.

Buffalo Bill begins his Wild WestShows in 1882

The transit of Venus, 1882• “Modern” equipment

using “state-of-the-art” 5-inch refractorsand glass photographicplates.

Jesse James killed 1882

The transit of Venus, 1882

• Sun was to be above thehorizon for the entire transit,which began at 8:13 am St.Louis time and ended 6hours later.

• Faculty from WashingtonUniversity, St. LouisUniversity and ChristianBrothers College preparedto observe the transit.

Sitting Bull returns to UScustody in 1882, 6 yrs afterCuster’s Last Stand

St. Louis prepared, but cloudsinterfered

June 8, 2004Conditions were not favorablefor St. Louis. Only the last 42

minutes of the transit werevisible from St. Louis

June 8, 2004

• At sunrise, the Sun’sdisk was distorted dueto the atmosphere.

• By 6:05am Venus hadbegun exiting theSun’s disk

• Photo taken fromSpringfield, OH


Special phenomena

• One sight notseen in 1882 wasthat of acommercial jet asit transited theface of the Sun.

• Some sites inEurope reportedthe transit of theISS during thetransit of Venus


June 5, 2012 - Predictions

Warning #2




The transit of Venus, Jun. 5, 2012

• Transit starts at 5:07pm; Alt=35 deg, Az=272 deg

• Transit ends at sunset 8:19pm; Az=300 deg

• Scout the site a few days before the event

• Chose an observing site with a flat western horizon

• Avoid asphalt or concrete that creates heat waves that willdistort your images

• Use specially filtered telescope or binoculars, Venus is barelyresolvable with unaided eye. 30X is needed to make Venusappear as large as the Full Moon to the unaided eye.

• Shade can be important. Consider a light block of some kind.Keep your equipment cool

I --First Contact Venus is invisibleuntil it makes contact with theSun’s edge. Look for a notch togrow

II – Second Contact Venus’s disk iscompletely on the Sun

It will take about 16 minutes fromFirst Contact for Venus to reachSecond Contact

Universal Time -Subtract 5hours toconvert UTto CDST

The transit of Venus, Jun. 5, 2012• First Contact 5:04pm• Venus makes first contact

on the NE edge of theSun’s limb

• Using the horizon as 3and 9 o’clock positions,Venus will contact theSun at the 1 o’clockposition

• Use an accurate clock ortime signals to catch thefirst contact

The transit of Venus, Jun. 5, 2012• Use high power, look

for halo effect asVenus moves onto theSun

• A 12-bit or higherresolution cameramay capture thiseffect. Post-processthe image to “stretch”the image

The transit of Venus, Jun. 5, 2012• Second Contact 5:21pm• 16 minutes after first

contact Venus furthestlimb will enter

• Look for black drop-effectas Venus moves awayfrom Sun’s limb

• Typically the larger thescope and higher themagnification the lesspronounced the black-drop effect should appear

The transit of Venus, Jun. 5, 2012

• Here is a sequence from 2004 with Venus leaving theSun’s disk

Orion Videoeyepiece with

12” SCT

The transit of Venus, Jun. 5, 2012• As Venus moves across

the Sun look for closeencounters with sunspots

• There have been noreports of strangephenomena as Venuspasses over sunspots, sowatch carefully and reportany strange effects

The transit of Venus, Jun. 5, 2012• When sunset occurs at

8:19pm Venus will bemidway across theSun’s disk.

www.transitofvenus.org

www.facebook.com/groups/108400462513165/

www.transitofvenus.nl

http://sunearthday.nasa.gov

Resources

ResourcesSky and Telescope Magazine

http://www.skyandtelescope.com/observing/objects/sun/3304056.html?page=1&c=y

http://www.skyandtelescope.com/equipment/vendors/3304076.html

http://science.nasa.gov/science-news/science-at-nasa/2003/30may_solareclipse2/

Solar Filter Safety

Solar Filter Suppliers

Solar Pinholes

Warning #3




What are my viewing options?

UNSAFE Solar ViewingMethods

SunglassesMultiple SunglassesMylar BalloonsMylar Food Wrappers (Pop Tart Bags, etc.)Smoked Glass X-Ray FilmFilm NegativesCD's or CD-ROM'sStacked Welder's GlassLiquid FiltersCoffee, Sun tea.Eyepiece Solar FiltersEclipse Glasses and Telescopes Together

Jul 10, 1972

SAFE Solar Viewing Methods

Indirect Viewing MethodsPinhole ProjectionTelescope ProjectionViewing with camera or video

Direct Viewing MethodsNaked-Eye Solar FiltersTelescope or binoculars with Filters

Pin-hole Projection

• A small hole in abox or card canform an image ofthe Sun

• Very small image• Not for Venus

Transit

Pin-hole Projection• The geometric size of the Sun’s image ½

degree is determined by the distance fromthe pinhole to the projection screen

• The diffraction quality of the Sun’s imageis the ratio of the pinhole diameter and thedistance to the screen. Must be at least 500to 1 ratio

PinholeScreen

>500:1

Pin-hole Projection• Box at least 5 feet long, a piece of aluminum foil, a pin, and a sheet of

white paper.• The longer the box, the bigger the pinhole image. To find the size of the

image, multiply the length of the box by the number 0.00873. For a box5 feet (60 inches) long, your solar image will be 60 x 0.00873 = 0.52inches in diameter. A 1mm pin at 60” is a ratio of 1500:1

On thisscaleVenuswould be0.4mm indiameter!

Pin-hole Projection

• Multiple images can be formed withpaper or leaves on a tree

Pin-hole Projection

• Even a mirror canform an project animage of the Sunonto a shadowedside of a building

• Larger image butstill not for VenusTransit

• 2” mirror at 230ftRatio=1300:1Sun dia=24”Venus dia=0.8”

Solar Glasses

• Speciallydesigned solarfilter, such asthe one usedin

eclipseglasses

Need 20/20 tosee Venuswith unaidedeye

Dec 13, 1974

Summary

• Pin-hole projection good for eclipses,but projection distance must be >60” tosee good size image

• Pin-hole not good for seeing Venustransit with any detail

• Solar glasses are good for eclipses• Need 20/20 to see Venus with unaided

eye

Solar Projection with a telescope

• Using a telescopeor binoculars toproject the Sun’simage is the bestand safest way toobserve an eclipseor transit

• Warning: Suncould damageyour optics!

• Instructions:• http://www.exploratorium.edu/transit/optical-

instructions.pdf


• Venus will be1cm in diameterif the Sun’simage is 30cm

• 1973 photo of a6-inch reflector,using Solarprojection

• 1999 photo ofMercury transit

Solar Projection

• Simple but effectiveSolar viewers

• SolarScope $80-250depending on model

http://www.solarscope.com/us/index.us.html

Solar Projection

• Simple but effectiveSolar viewers

• Sunspotter $500!!Various sources


• Simple projectionsystems can be madefrom buckets orfunnels

• I don’t recommendusing reflectingtelescopes forprojection, dangerousif Sun missessecondary mirror andsomeone looks downthe tube

Solar Funnel for Telescopes

• $10-20

Through the telescope white light filters

• In 2004 I used a 5 inch F/5 refractor with a 4 inchglass solar filter and 25mm eyepiece (25X). Iused a 2X barlow for 3rd contact.

• For 2012 I plan to use the Solar Funnel

Through the telescope white light filters• You need SAFE

solar filters• Glass or film• Make your own• Baader Film• $44-$90• Astro-Physics, Inc.

11250 Forest Hills Road,Machesney Park, IL 61115, U.S.A.


solar filters• Glass or film• $50-$100

• Buy alreadymounted

• Kendrick SolarFilters (film)


solar filters• Glass types• $50-$200

• Orion Telescopes• Thousand Oaks

Optical• J.M.B.

Safety tips• Tape or secure your filter on tightly, beware of

wind• Remove or cover all finders• Don’t use open tube telescopes• Don’t let people look down the open end of a

reflector• Don’t let anyone place their hand or their eye

between the eyepiece and the projection screen• Don’t leave your scope unattended

Camera

• Never use a camera or camcorder without a filter on yourtelescope

• In order to capture these phenomena, you will need longfocal lengths.

• The Sun subtends .009 radians and Venus .0003 radians.• The Sun’s disk will be 4.5mm in diameter with a 500mm

FL lens

FL=430mm FL=12000mmFL=5500mm

35mm Format

Camera

Resources:Fred Espenak’s site: mreclipse.com

35mm Format

Camera

• Example:

• 35mm format Camera

• 3.5” Questar

• EFL=1280mm

• Sun’s Image= 1280 x .009= 11.5mm

Video Observing

• A video camera andmonitor is a safe wayto observe the Sun.

• You can observe insideor shade

• Many people can viewat same time

• The effectivemagnification can bevery large

1994

1984

Video Eyepiece

• Most video eyepieces are 1/3” format• Image will appear bigger when displayed to same

size as 35mm format


Video Eyepiece

• Example:

• Orion video eyepiece

• Meade 12” SCT

• EFL=3050mm

Camcorder

• Most modern camcorders are ¼” (4.5mm) format• Zoom lenses on camcorders are confusing• It is best to try your camera well in advance.• Consider buying a tele-extender ($100)


Video Camera

• Examples• Sony camcorder with 18X

zoom

• Add 2X tele-extender (36X)

Specialty Telescopes• Narrow wavelength

images of Sun• $500-$5000

Other Considerations• Hopefully it will be a clear sunny day, so protect

you and your equipment

Documents

2012 viewing prospects for May Solar Eclipse and June ... · PDF fileHow often do Venus transits occur? ... 1882 2012 1874 1639 1769 1761 How many Venus transits have been seen? •The