We've had quite an interesting couple of weeks, astronomically speaking. First the solar eclipse at the end of last month, and just Tuesday, Venus transited the sun!
When Venus passes directly between earth and the sun, we see the distant planet as a small dot gliding slowly across the face of the sun. Historically, this rare alignment is how we measured the size of our solar system.
Transits of Venus have a strange pattern of frequency. A transit will not have happened for about 121 ½ years (prior to 2004, the last one was 1882). Then there will be one transit (such as the one in 2004) followed by another transit of Venus eight years later (in the year 2012). Then there will be a span of about 105 ½ years before the next pair of transits occur, again separated by eight years. Then the pattern repeats (121 ½ , 8, 105 ½ , 8).
If Venus and the earth orbited the sun in the same plane as the sun, transits would happen frequently. However, the orbit of Venus is inclined to the orbit of earth, so when Venus passes between the sun and the earth every 1.6 years, Venus usually is a little bit above or a little bit below the sun, invisible in the sun’s glare.
We watched it using a similar method as we used to watch the eclipse - a pinhole projector. We used binoculars to enhance the image of the sun projected on the paper though. And it worked!
You can see it as a little black dot on the white spot of the sun.
Enlarged and enhanced, you can see it slightly larger.
Did you miss this one? Are you looking forward to the next transit? Mark your calendars - you will be able to see it in 2017, in about 38536 days.
Pin It
When Venus passes directly between earth and the sun, we see the distant planet as a small dot gliding slowly across the face of the sun. Historically, this rare alignment is how we measured the size of our solar system.
Transits of Venus have a strange pattern of frequency. A transit will not have happened for about 121 ½ years (prior to 2004, the last one was 1882). Then there will be one transit (such as the one in 2004) followed by another transit of Venus eight years later (in the year 2012). Then there will be a span of about 105 ½ years before the next pair of transits occur, again separated by eight years. Then the pattern repeats (121 ½ , 8, 105 ½ , 8).
If Venus and the earth orbited the sun in the same plane as the sun, transits would happen frequently. However, the orbit of Venus is inclined to the orbit of earth, so when Venus passes between the sun and the earth every 1.6 years, Venus usually is a little bit above or a little bit below the sun, invisible in the sun’s glare.
We watched it using a similar method as we used to watch the eclipse - a pinhole projector. We used binoculars to enhance the image of the sun projected on the paper though. And it worked!
You can see it as a little black dot on the white spot of the sun.
Enlarged and enhanced, you can see it slightly larger.
Did you miss this one? Are you looking forward to the next transit? Mark your calendars - you will be able to see it in 2017, in about 38536 days.
Posts
Crazy how things just keep going around and around up there...
ReplyDeleteIt was fun to watch. MSN had it as a live feed and I found a cool astronomical site in the bargain.
ReplyDelete