Eclipses are for chumps (or, why I'm packing a winter coat to Hawaii)
Most people following my LJ probably already know or have heard of transits of Venus, and given that the media build-up is starting, you possibly/probably also know that the next and last opportunity available to the vast majority of us to see one will occur next Tuesday/Wednesday (depending on local time).
Just to get this out of the way: DO NOT LOOK DIRECTLY AT THE SUN, ESPECIALLY THROUGH BINOCULARS OR A TELESCOPE! Permanent eye damage occurs immediately and without warning (there are no pain receptors in the retina, just the blink reflex of the eye)! Use pinhole projection, or through binoculars (you only need to project through one side, so you can cover up the other one; hold a sheet of paper under the eyepiece -- this works better if you stand with your back to the sun and shade the paper with your body; just don't stand between the eyepiece and the paper, obviously). Or watch one of the bazillion live feeds that will certainly be going.
If you don't already know, the general definition of a transit in astronomy is when from a particular viewer's perspective, one object passes in front of another object (if the relative sizes and distances are such that the foreground object completely obscures the background object, that's an eclipse). Thus, for Earth-bound viewers, the only planets that can transit the sun are Mercury and Venus. Transits of Mercury are relatively frequent; the last couple were in 1999, 2003 and 2006 (I posted some photos -- scroll back to Nov. 2006 under my "mercury" tag) and the next one will be in 2016. Transits of Venus are much rarer; they occur in pairs 8 years apart, and the interval between pairs alternates between 105.5 and 121.5 years. The last one was in 2004; the next one occurs next week; and the next one after that will be in 2117.
A more detailed explanation with diagrams etc. can be found here; the Wikipedia page speaks more to the historical and scientific significance of transits.
To me it is nothing short of astounding that scientists were able to predict the 1631/1639 transits and use them to gauge the relative sizes and distances of the Sun/Venus/Earth, and in 1761/1769 to calculate the absolute size of the solar system. I also find them interesting as temporal markers of civilization -- the last pair was in 1874/1882; in 2004 observations of the event were broadcast live worldwide on the Internet. It is conceivable a young child alive today might live to see the 2117 transit, and with reasonable advances in medicine it seems safe to assume there will easily be people who are alive for both the 2125 and 2247 ToV (assuming we haven't wiped each other out or rendered the Earth uninhabitable by then).
Next week's event will be visible from all of North America (more detailed info, including worldwide visibility maps and timetables (including major cities in the U.S. and Canada) can be found here), although for most of NA the transit will still be in progress at sunset. This is not as disappointing as it may sound -- the most interesting parts are 1st and 2nd contact (which are, respectively, when Venus appears to touch the sun from the outside, and when it has completely "entered" the disk of the sun), and that only covers the first 18 minutes. After that Venus takes 6 hours to cross the face of the Sun, followed by 3rd and 4th contact which again come ~18 minutes apart.
Barring a medical miracle, I knew 2004/2012 would be the only two observational opportunities in my lifetime, and since the 2004 event wasn't visible from the U.S. I traveled to England along with my friend Gina. This was perhaps a dubious choice of locale, given the weather reputation there, but this was June after all. Also, there were a number of outfits offering travel packages to places like Central Europe, Egypt, and South Africa, but England seemed like a good compromise considering the various factors like geopolitical stability, travel hassle, and overall cost. I also scheduled a week-long Globus tour for after the transit so it wouldn't be a total loss in any case, and as it turned out, the skies were clear (and it was scorching hot, 90+F most of the week. I think it only rained once.)
Given the circumstances, I engaged in what is probably a shockingly minimal amount of planning for the event itself -- we arrived in London the day before the transit, and after ascertaining that the Science Museum didn't have any special program planned for 1st/2nd contact (the transit began shortly after 6 AM local time), I went with plan B, which was to find a way to get to Greenwich at the asscrack of dawn (answer: an expensive private car hire/taxi from the hotel) so we could join the crowd at the Royal Observatory (which felt more historically/scientifically appropriate anyway). We spent the time between 2nd and 3rd contacts touring the Observatory (ISTR I avoided having a cliched picture taken of me straddling the Prime Meridian) and the nearby National Maritime Museum and afterward took light rail/tube back to London.
Having accomplished my goal of viewing a transit in person, I could probably give the 2012 event a miss, especially given Internet coverage etc., but there's still something about seeing it live, plus this only happens twice a lifetime, so what the hell. I booked a package in Hawaii that includes exclusive access for our group to view the transit from atop Mauna Kea (thus the need for a winter coat), which should be pretty fucking awesome. On the days/after our itinerary includes science lectures and a tour of the Keck Observatory; besides the down time, I'm also staying 2.5 days afterward on my own since, you know, it's Hawaii (my first time, too).
Just to get this out of the way: DO NOT LOOK DIRECTLY AT THE SUN, ESPECIALLY THROUGH BINOCULARS OR A TELESCOPE! Permanent eye damage occurs immediately and without warning (there are no pain receptors in the retina, just the blink reflex of the eye)! Use pinhole projection, or through binoculars (you only need to project through one side, so you can cover up the other one; hold a sheet of paper under the eyepiece -- this works better if you stand with your back to the sun and shade the paper with your body; just don't stand between the eyepiece and the paper, obviously). Or watch one of the bazillion live feeds that will certainly be going.
If you don't already know, the general definition of a transit in astronomy is when from a particular viewer's perspective, one object passes in front of another object (if the relative sizes and distances are such that the foreground object completely obscures the background object, that's an eclipse). Thus, for Earth-bound viewers, the only planets that can transit the sun are Mercury and Venus. Transits of Mercury are relatively frequent; the last couple were in 1999, 2003 and 2006 (I posted some photos -- scroll back to Nov. 2006 under my "mercury" tag) and the next one will be in 2016. Transits of Venus are much rarer; they occur in pairs 8 years apart, and the interval between pairs alternates between 105.5 and 121.5 years. The last one was in 2004; the next one occurs next week; and the next one after that will be in 2117.
A more detailed explanation with diagrams etc. can be found here; the Wikipedia page speaks more to the historical and scientific significance of transits.
To me it is nothing short of astounding that scientists were able to predict the 1631/1639 transits and use them to gauge the relative sizes and distances of the Sun/Venus/Earth, and in 1761/1769 to calculate the absolute size of the solar system. I also find them interesting as temporal markers of civilization -- the last pair was in 1874/1882; in 2004 observations of the event were broadcast live worldwide on the Internet. It is conceivable a young child alive today might live to see the 2117 transit, and with reasonable advances in medicine it seems safe to assume there will easily be people who are alive for both the 2125 and 2247 ToV (assuming we haven't wiped each other out or rendered the Earth uninhabitable by then).
Next week's event will be visible from all of North America (more detailed info, including worldwide visibility maps and timetables (including major cities in the U.S. and Canada) can be found here), although for most of NA the transit will still be in progress at sunset. This is not as disappointing as it may sound -- the most interesting parts are 1st and 2nd contact (which are, respectively, when Venus appears to touch the sun from the outside, and when it has completely "entered" the disk of the sun), and that only covers the first 18 minutes. After that Venus takes 6 hours to cross the face of the Sun, followed by 3rd and 4th contact which again come ~18 minutes apart.
Barring a medical miracle, I knew 2004/2012 would be the only two observational opportunities in my lifetime, and since the 2004 event wasn't visible from the U.S. I traveled to England along with my friend Gina. This was perhaps a dubious choice of locale, given the weather reputation there, but this was June after all. Also, there were a number of outfits offering travel packages to places like Central Europe, Egypt, and South Africa, but England seemed like a good compromise considering the various factors like geopolitical stability, travel hassle, and overall cost. I also scheduled a week-long Globus tour for after the transit so it wouldn't be a total loss in any case, and as it turned out, the skies were clear (and it was scorching hot, 90+F most of the week. I think it only rained once.)
Given the circumstances, I engaged in what is probably a shockingly minimal amount of planning for the event itself -- we arrived in London the day before the transit, and after ascertaining that the Science Museum didn't have any special program planned for 1st/2nd contact (the transit began shortly after 6 AM local time), I went with plan B, which was to find a way to get to Greenwich at the asscrack of dawn (answer: an expensive private car hire/taxi from the hotel) so we could join the crowd at the Royal Observatory (which felt more historically/scientifically appropriate anyway). We spent the time between 2nd and 3rd contacts touring the Observatory (ISTR I avoided having a cliched picture taken of me straddling the Prime Meridian) and the nearby National Maritime Museum and afterward took light rail/tube back to London.
Having accomplished my goal of viewing a transit in person, I could probably give the 2012 event a miss, especially given Internet coverage etc., but there's still something about seeing it live, plus this only happens twice a lifetime, so what the hell. I booked a package in Hawaii that includes exclusive access for our group to view the transit from atop Mauna Kea (thus the need for a winter coat), which should be pretty fucking awesome. On the days/after our itinerary includes science lectures and a tour of the Keck Observatory; besides the down time, I'm also staying 2.5 days afterward on my own since, you know, it's Hawaii (my first time, too).