Venus Transit - 2012The last one of YOUR lifetime…

Jim WesselJohnson Space Center Astronomical Society

Transits occur at Conjunctions• I suppose I should clarify that, and say inferior

conjunctions.

View of top of the Solar System

Venus

2117 21252004 20121882187417691639 1761

121 ½ 121 ½ 105 ½105 ½

8 8888

Periodicity of Venus Transits• Venus transits feature a repeating pattern every 243

years.

• At this time (2012), after a pair of transits, 105.5 years will pass, then a first transit happens, then 8 years pass, then the second transit occurs. Then 121.5 years pass, and the transit pair repeats.

Mercury Transits• Orbits in 88 days.

• It’s inclination to the ecliptic is 7° (Venus is 3.4°, Earth is 0°).

• Mercury’s orbital eccentricity is .205 (compared to Venus at .006 and Earth at .0167).1. Kepler’s laws vs. perihelion and aphelion.

2. Parallax

Historical Info:• Ancient cultures (Greek,

Babylonian, Egyptian, Chinese, Mayan) were aware of Venus as a planet, but did not mention transits.

• The first claimed observation of a Venus Transit was in 1032 by Avicenna.

Babylonian Venus Tablet

1631 and 1639 Transits

Johannes Kepler Pierre Gassendi

Jeremiah Horrocks

1663

James Gregory

1716

Edmond Halley

• Concept stealer?

• Provided additional direction for Venus transit observation and timing.

1761 Transit

Mikhail LomonsovMap of the World, circa 1761Venus, via Pioneer flyby, NASA

1769 TransitLt. James Cook

HMS Bark Endeavour, replica

Map of Tahiti

Point Venus

Jérôme Lalande

Fort Venus

Black Drop Effect

Simon Newcomb

1874 and 1882 Transits

2004 event

• Head WEST, young man!

• A flat, western horizon is preferred.

• Texas

Planning:

< California < Hawai’i < TAHITI

Transit Times• 4 Contact points (we’ll see 2…) • First Contact

• Second Contact

• Greatest Transit

= 5:09:38pm CDT

= 5:27:34pm CDT

= 8:29:36pm CDT

8:40pm

1st2nd

GT

Sunset ~ 8:40pm

• Where do you expect to observe the transit?

• Typically, western Texas has less clouds than Houston - Make your travel arrangements according to the level of risk you are willing to accept.

• Stay on top of the weather several days in advance. www.weather.com , www.noaa,gov , www.intellicast.com , www.accuweather.com

• Confirm your viewing method in advance. Use approved solar filters, pinhole projection, others… PRACTICE beforehand.

• Do you intend to record the transit? If so, how?

Planning:

Remember, this is 1x / rest of your life…

Solar TelescopesCoronado/MeadePST (PersonalSolar Telescope)40mm, F/10

$499.00

Lunt LS35THa35mm $598.00

Coronado/MeadeSolarMax II90mm, F 8.8$4399.00

Lunt LS80THa80mm $3246.00

• From personal experience, I can tell you these work nicely at a reasonable price point. But, they aren’t perfect…

Solar Filters

• If you intend to use a projection method, try it out in advance!

Projection viewing

• Practice with your system before the big day.

• 1st class astrophotographysetups can run several $K…

Economic Imaging Equipment:

HIGHLY recommended

Even the Hubble Space Telescope is getting in on the act…

If you are clouded out… (Boo Hiss)

http://sunearthday.nasa.gov/2012/transit/webcast.php

Or Google search “Live webcasts of Venus Transit 2012”

You chose…

… Poorly.

Sources Cited:Wikipedia

http://www.captcook-ne.co.uk/ccne/index.htm

www.transitofvenus.org

www.transitofvenus.nl

http://sunearthday.nasa.gov

http://cdn.transitofvenus.org/docs/Build_a_Sun_Funnel.pdf

http://eclipse.gsfc.nasa.gov/transit/venus0412.html

http://www.scientificamerican.com/article.cfm?id=sun-of-a-gun

5 gal bucket

oil funnelprojector