Mercury Transit Views | 11 Nov 2019

My hopes were high to be able to see Mercury during transit with my own optical equipment. But, the weather didn’t cooperate. Our morning was cloudy as 2″ of snowfall was ending. A few moments of sunshine came as the transit ended. But, efforts to get a photo failed. Instead, I visited the space-based Solar Dynamics Observatory to watch the event. They put on a great show at their dedicated transit site. The images and videos are archived there and can be visited any time.

Here is a sample. Watch the planet Mercury cross from left to right during the 5.5hr event. It is very small. This video and all images in this post are “Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.”

Perhaps you wondered why the Sun looked an odd color and appearance. That is because of the wavelength of light used. SDO simultaneously images the Sun in 10 wavelengths. It takes images in 10 wavelengths every 10 seconds. Those are stitched together to show the dynamic activity of the Sun. For example…

The transit was tracked as it started (ingress) in the multiple wavelengths below. Each wavelength is associated with different temperatures and energies at the Sun’s surface. They are colorized to make them easily distinguished from the others. SDO also tracked Mercury in a magnified view as it made its way across and also at the end of transit (egress).

“Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.”

As the transit unfolded, I captured short videos in the different wavelengths as Mercury was tracked. These videos were stitched together into a smooth transition from one color to the next.

The next transit of Mercury will be in 2032. The orbit of the planet is tilted with respect to our orbit and prevents a transit alignment for quite a while. Don’t hold out hopes for the next Venus transit. It will not occur until 2117.

Right Place | Right Time

Sometimes things work out just right. The Sun was high about 2pm in very clear blue sky. The Space Station passed over me and did a very brief transit of the Sun lasting only 0.63 sec. I drove 2 miles and put myself as close to the centerline as possible. The path of visibility was only about 3 miles wide. I needed to be in the right place at the right time. The video is slowed to 10% normal speed so you don’t blink and miss the transit.

Frame grab of the ISS in transit. Solar panels easily visible.

Of course, it is easy to be in the wrong place at the wrong time, or the wrong place at the right time. One of my favorite performers, Dr. John, captured the situation of being in the right place at the wrong time. Enjoy.

Ice Ring Halo

I stepped outside and looked up toward the sun. An arc of faint color caught my attention. It was actually a full circle of color around the sun. These halos are 22˚ in radius from the sun caused by refraction of light through ice crystals of the high cirrus clouds between me and the sun. The color saturation has been enhanced a little to show the redness of the inner edge and blueness of the outer edge due to their different wavelengths of light.

I went out several minutes later. The cirrus clouds were gone, as was the halo. It was my lucky day.

Cast a Long Shadow

Previously, I shared a post about a conversation with my son about the rising sun viewed at different latitudes. During that conversation, we also discussed how the length of our shadow varied over the course of a year. In winter at noon in the northern hemisphere, when the sun is low in the sky, our shadows are cast long to the north. In summer, our shadows are shorter due to the higher angle of the sun in the sky.

Imagine a plane extending through the earth at the equator. Extend that equatorial plane out into space. Between late March and late September, the sun appears above that plane. It reaches its highest extent in late June at the summer solstice. The sun appears at the elevation of the plane on the equinoxes in late March and late September. It appears at its farthest extent below the equatorial plane in late December at the winter solstice. The farthest north and south of the equatorial plane reached by the sun is 23.5˚.

Normal Shadows

Melanie and I live about 42˚ north of the equator. In the summer months, the sunlight direction is above the equatorial plane several degrees. Our short shadows are cast to the north at noon. In the winter months, the sunlight direction is below the equatorial plane. Our shadows are cast longer to the north. The blue man in this figure is not to scale, but illustrates the concept of casting of shadows.

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Noon @ Ollantaytambo

We climbed the 245 steps to the top of the Inca ruins at Ollantaytambo in Peru and reached the Temple del Sol. It was noon with the sun high overhead. Someone looked up and noticed an ice ring encircling the sun. I had to capture this photo.

I grew up and continue to live at about 40-42˚ north latitude in the center of the U.S. The sun has never been directly overhead. But now, at noon about 13˚ south latitude, the sun was nearly straight up. I looked down to my feet and saw something I’d never seen before. My shadow was directly below me. That was fun to see.