Today the Earth is closest to the Sun, a point called perihelion. We will be about 147,098,290km (91,402,639miles) from the Sun. Compare this to the 152,098,232km (94,509,459miles) we will be at aphelion on July 4th, a difference of about 5,411,169km (3,362,344miles) occurs throughout one orbit.
It may seem odd that we are actually at the closest for the middle of northern winter, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.
As we approach solar maximum, large sunspot groups have again become a common sight. The last few years have seen an unusually quiet solar minimum, long stretches of time when not a single sunspot appeared. that has certainly changed, the Sun is now dotted with sunspots, with the occasional monster. At it’s peak, AR1339, seen above, was over 100,000km across. That is larger than 15 Earths, side by side. I mean monster!
The photo was taken with the Canon 60D, a 0.8x TeleVue adaptor, a C-11 and a Thousand Oaks full aperture solar filter.
Sunspot group AR1339 as seen on the afternoon of 5Nov2011
About a dozen times a century Mercury passes in front of the Sun as seen from Earth. The event is observable with a modest telescope and a solar filter, Mercury can be seen as a small black dot crossing the surface of the Sun. If half of those happen when the sun is below your horizon the average person will have the chance to observe five or six in a lifetime. Since the next opportunity will not occur until May 9th, 2016 I didn’t want to miss this one!
90mm refractor Violet Haze photographing the transitI took the day off.
Considering that Mercury never gets very far from the Sun means that most of the time you can observe Mercury it is low on the horizon and is typically seen through a great deal of atmospheric distortion. A transit is one exception to this, during a transit mercury is a sharp disk, very different from the multicolor jello ball that is usually seen.
The 2006 Transit was well timed for observation across western North America, starting just after noontime and ending at 5:09pm MST. This put the Sun high in the sky for all but the last part of the event. Our weather cooperated as well, delivering a cloudless blue sky the entire day in place of the clouds that had been forecast. The air was reasonably steady as well allowing good photographic and observing conditions.
I took advantage of the weather and photographed almost the entire transit, all but the very end when the sun sank below the trees in my neighborhood. I used the Canon 20Da and setup a timer to shoot every 5min. The only issue was the inability to do a polar alignment on the mount when setting up in the middle of the day. The result was I had to manually guide the scope every 10-15 min to keep the sun centered.
I got plenty of good photographic material, enough for a few single photos as well as an animation of the transit. A transit is an impressive demonstration of the scale and arrangement of our solar system. Not hard to visualize the reality of those textbook drawings of planetary orbits after you have had such an opportunity to see the real thing.
No complaints on my second Mercury transit.
The Mercury transit of 8 Nov 2006 in progress. Mercury is about halfway between the center to the bottom, a large sunspot complex is visible on the left edge. Photo with a 90mm APO refractor, a Thousand Oaks full aperture filter and a Canon 20Da camera.
