Observing Prospects for May 20, 2012 Partial Solar Eclipse and June 5, 2012 Transit of Venus
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”
Sony Super 8 Camcorder with 2X Tele
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
Sony Super 8 Camcorder with 2X Tele
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
Sony Super 8 Camcorder with 2X Tele
June 5, 2012 - Predictions
Warning #2
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.
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
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.
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
Solar Projection with a telescope
• 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
Solar Projection with a telescope
• 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.
Through the telescope white light filters• You need SAFE
solar filters• Glass or film• $50-$100
• Buy alreadymounted
• Kendrick SolarFilters (film)
Through the telescope white light filters• You need SAFE
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
FL=105mm FL=2600mmFL=1300mm
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)
FL=55mm FL=1500mmFL=700mm
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