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This article is from the In-Depth Report The 2012 Transit of Venus

Live Chat: The 2012 Transit of Venus, with SA Editor George Musser

Musser, who covers space for SA, will help us prepare to watch Tuesday's transit and explain the science behind this rare astronomical event
venus transit, venus, sun,



Flickr/NASA Goddard Photo and Video

Join us below at 3 pm Eastern on Tuesday (June 5) for a live 30-minute online chat with SA Editor George Musser, who will discuss the transit of Venus occurring later that evening. We invite you to post chat questions in advance in the comments below.

On June 5 in the Americas and June 6 in the rest of the world, people will be able to see one of the rarest predictable events in astronomy: a solar transit of the planet Venus. Over a six-hour period the disk of Venus will be silhouetted against the sun. Seeing it safely requires a special eye-protection filter, or a telescope or binoculars can safely project an image onto a wall or sheet of paper. But if you miss it, your next chance won't come until the year 2117.

CHAT TRANSCRIPT

Robin Lloyd
Hi everyone. I'll be the host of today's chat -- I'm Robin Lloyd, Scientific American's news editor. But George Musser will be the star of this show.

George Musser
No, the sun will be.

Robin Lloyd
:)

Robin Lloyd
OK let's get started. Welcome everyone to our live 30-minute chat on the transit of Venus, with Scientific American's space editor George Musser

Laura Salgado
hello from Mexico City!

George Musser
Hi everyone!

Robin Lloyd
George Musser is a senior editor at Scientific American whose primary focus is space science, ranging from planets to cosmology.

Robin Lloyd
Hi Laura!

George Musser
@laura how's your weather?

Laura Salgado
rainy day but hot

Robin Lloyd
Just fyi: Musser has won many awards, including the 2010 American Astronomical Society's Eberhart Planetary Sciences Journalism Award. But on with the show.

Mary Starr
Good afternoon from Southeast Michigan where the weather is mostly cloudy.

Robin Lloyd
The #1 thing most people want to know is how to watch tonight. Here is a great overview: http://blogs.scientificamerican.com/observations/2012/06/05/where-to-watch-the-transit-of-venus/

Robin Lloyd
Hi Mary

George Musser
@mary @laura yeah, we have clouds here in New York, too

Robin Lloyd
Yes, everyone give us your weather info! Of course, it's easy to watch this event online too as our post on 'where to watch' states.

George Musser
But go out there anyway... you just need the clouds for part for a few seconds.

DaAmazingUmAh
hmmm if its 21h02 here I'm pretty sure I've missed the show you are all going to see :(

George Musser
@da'ah where are you?

Robin Lloyd
So George, what are your viewing plans for this evening?

George Musser
@robin I'll go to Riker Hill in Livingston, NJ, which has an excellent view of the western horizon. The local amateur astronomers will be there in force.

DaAmazingUmAh
South Africa , it be really darkest africa , right now :)

Mary Starr
We will be watching through a telescope with a filter and I fully expect the clouds to disappear right around 6 p.m.!

George Musser
@daAmazingUmAh it'll be visible, just, from the far east of the country, around Kruger

Laura Salgado
what about Mexico City?

George Musser
@laura yes, Mexico has excellent visibility, assuming the weather cooperates

George Musser
@mary yay!

Robin Lloyd
wow -- so will you bring a telescope, George?

George Musser
@robin no, i'll rely on the others'

Robin Lloyd
George, what intrigues you most about this year's transit?

George Musser
@robin well, it intrigues me for personal reasons: that my daughter can see it... she was only a year old in 2004

markfischetti
My question: Why is the transit pattern two within a couple years, then nothing for a century?

George Musser
@markfischetti the orbit periods of Earth and Venus are almost but not quite in an integer ratio

jmtsn
@Mark, I was just wondering that too...

George Musser
@markfischetti @jmtsn so one transit is (usually) followed by another 8 years later... it's 8 years minus two and a half days. in those 2 1/2 days, Venus moves vertically about 1/3 degree... the sun is 1/2 degree in size from Earth

RPGlennJohnson
got some binocs on a tripod here at work to project on a whiteboard for students as they come into class tonight....

George Musser
@rpglennjohnson excellent, that's the best way, I think

macjohn
is a neutral density filter on a DSLR with short exposures and small aperture enough to prevent damage to my camera?

George Musser
@macjohn hmm, not sure

jmtsn
Hey George, does Mercury ever transit the sun?

RPGlennJohnson
cloudy here in SW ohio right now tho

George Musser
@jmtsn it does indeed... see http://eclipse.gsfc.nasa.gov/transit/catalog/MercuryCatalog.html for the schedule

George Musser
@rpglennjohnson yes, I've been watching the satellite images... clouds over much of the country

Robin Lloyd
slooh.org is a good place to watch if weather fails, but George is urging us to watch the skies for a break in the clouds

George Musser
@robin yes, you really do want to give yourself every opportunity to see it live. from the East Coast of the U.S., once the sun sets, the transit still has four hours to go... so you can go home then and watch on the web

RPGlennJohnson
@george....indeed...simple and

RPGlennJohnson
multiple people can view....we are a bit on the edge of a mass of clouds, but some sun peeks

George Musser
@rpglennjohnson be sure to post your results afterwards in the comment field below

Robin Lloyd
It's not a naked eye event, is it.

George Musser
@robin no, goodness no, you need eye protection... but in 2004 I watched with eclipse shades. you can just about make out the dot without a projector or scope

markfischetti
Good point @gmusser. We think of transit as if the moon is passing by in an eclipse, taking only a few minutes.

markfischetti
But you've got 6 hours. So try to watch live. Then go to the Web later.

George Musser
@markfischetti ah, yes, good to remind everyone that the event lasts 6+ hours

Robin Lloyd
from @ZSIZGORIC on twitter? What will be the effect of this transit on science?

George Musser
@robin @zsizgoric frankly it's not a ginormous effect... there are a few unresolved details such as the nature of the black drop effect, but mostly this is for fun. also, it's an example of a technique to search for extrasolar planets

RPGlennJohnson
i live introducing people to astronomy via celestial events like this

George Musser
@rpglennjohnson it's amazing how this draws people in, isn't it?

RPGlennJohnson
@george....yes it is

Katrina Gill
I don't know the how or the why of this event, but the Majesty of it, is what amazes me, I'm always looking at the sky

jmtsn
George, how do you rank a Venus transit compared to a solar eclipse or a lunar eclipse?

George Musser
@jmtsn well, it's not as dramatic as an eclipse, but I think the obscurity is part of the fun

George Musser
at the time of the 2004 transit, no one alive on Earth had ever seen one

George Musser
ditto for 2117

George Musser
fun fact: Venus always shows the same side to us at a transit... exactly 25 Venus days pass between successive transits. there is a truly remarkably, presumably coincidental, commensurability of orbits and rotation periods

Ana Sofia Alvarez
How can I protect my eyes if I don't have special glasses?

George Musser
@ana here are some strategies: http://transitofvenus.nl/wp/observing/six-ways-to-see-the-transit/. also http://www.scitech.org.au/featured/featured/transit-of-venus.html

R. Alan Squire
I'll have to catch the final footage on the Web... Here in Nova Scotia, it's hard to tell if there even *is* a sun ;)

George Musser
it's very easy to take a piece of cardboard or foil and make a pinhole

Ana Sofia Alvarez
Thanks! So glad I'll get to see this. Lifetime event.

Nathan Henderson
Looking forward to it....even though I don't have the 'high tech' imaging equipment that the professionals use....projection all the way!!

George Musser
@alan alas

George Musser
@nathan that's the way to go.... it's not like, saying, Mars or the rings of Saturn, where better equipment =

minfy133
Why is the Transit of Venus so rare? Shouldn't it be less rare than Mars since it orbits the Sun faster?

George Musser
... better result - key here is just to see the black dot

George Musser
@minfy133 well, Earth is moving too, so the two planets come into the same relative orientation every 584 days. what gives the transit a regular period is that 5 * 584 days = 8 years. now, the next ingredient is that Venus's orbit plane intersects Earth's in two places ,corresponding to where Earth is positioned in June and December. so, if Earth and Venus lie in the same plane, as they did on June 8, 2004, they will again lie in the same plane 8 years later.

minfy133
Oh I see... but where did the 5 come from the 5 * 584 calculation?

George Musser
@minfy133 just from looking for the next integer multiple. 584 days = 1.6 years = 8/5 years, so when Earth does 5 laps, and Venus 8, they return to where they were. the trick, though, is that the ratio is not EXACTLY 1.6, but 1.59-something. (off by about 2 1/2 days)

Chapterless
Do you know how this first transit was observed? With what technology?

George Musser
the first one DELIBERATELY observed (and recorded) was in 1639

minfy133
Oh! I understand now! Thanks ^^

George Musser
@chapterless the two English astronomers who say it used rudimentary telescopes

Mary Starr
FWIW: http://en.wikipedia.org/wiki/Transit_of_Venus,_1639

Robin Lloyd
Here's a chapter that describes the transit observation and prediction by Horrox in 1639:
http://www.scientificamerican.com/article/man-who-knew-venus-would-transit-sun-excerpt

jmtsn
So the ~2.5 days explains why we won't see another transit 8 years from now?

George Musser
@jmtsn exactly, because the alignment betweenVenus and Earth won't occur where their orbit planets intersect

suitti
I saw the 2004 Transit. I'm bringing a white light 10' scope to a public event, uhm, real soon.

George Musser
@suitti did you get any images?

suitti
Back in 2004, it was a morning event, and we caught the last half hour.

Mary Starr
@chapterless @george It is amazing that they were 'colleagues' of Kepler

suitti
I used a spotting scope & eyepiece projection onto white paper.

hmackyn
do you know if you'll be able to see the transit through clouds very well?

George Musser
@hmackyn doubtful

suitti
I got some pictures, but they're not online. Pictures of the white paper.

George Musser
@suitti with the image of Venus? why don't you send it to me via Twitter to @gmusser?

Robin Lloyd
Thanks everyone for joining us. We'll close this down in a minute. Again, here is a great overview on how to watch tonight: http://blogs.scientificamerican.com/observations/2012/06/05/where-to-watch-the-transit

Robin Lloyd
Yes, feel free to contact us on Twitter -- @gmusser or @SciAm or @robinlloyd99

Mary Starr
Thanks George - it was fun. Have a great evening everyone

BoraZ
Thank you!

George Musser
be sure to download the mobile app if you have iOS/Android

Robin Lloyd
And comment below or on FB later on to let us know what your viewing experience was like!

Robin Lloyd
what's it called, George?

George Musser
app info: http://www.transitofvenus.org/education/video-new-media/217-phone-app

Robin Lloyd
this one? http://www.scientificamerican.com/article/transfer-venus-app-enables-cosmic-calculations-next-tuesday

George Musser
yup

Robin Lloyd
thanks so much George and everyone who visited. happy skywatching!

hmackyn
Thank you!

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