ENTERING THE SOLAR WIND STREAM: As predicted, today Earth is feeling the first brush of a solar wind stream that could envelop our planet for the rest of the week. Last night, the stream's leading edge sparked a bright display of auroras over Scandinavia, shown here in a photo from Ole Salomonsen of Tromsø, Norway:
"I drove about an hour from Tromsø and stopped by a river--a great place for reflections," says Salomonsen. "Strong auroras were dancing overhead. It was a fantastic display."
The solar wind is flowing from a large hole in the sun's atmosphere. NASA's Solar Dynamics Observatory photographed the yawning structure directly facing Earth on Jan. 3rd:
Coronal holes are regions where the sun's magnetic field peels back and allows solar wind to escape. The stream of wind emerging from this coronal hole recently blew past NASA's STEREO-A spacecraft with peak speeds near 700 km/s. Now it's our turn as the stream reaches Earth.
NOAA forecasters say there is a 60% to 65% chance of polar geomagnetic storms on Jan. 4th-5th as the fast-moving stream buffets our planet's magnetic field. Residents of the Arctic should expect G1-class geomagnetic storms and bright auroras in the nights ahead. Free: Aurora Alerts.
ANALEMMA TIMES 9: If you took a picture of the sun at the same time each day, would it remain in the same position? The answer is no, and the figure-8 shape traced out by the sun over the course of a year is called an "analemma." Over the years, many photographers have created analemmas. In 2016, however, Steven Riegel of Colorado Springs CO took it up a notch. He photographed the sun 9 times a day, creating the rare nonalemma:
"I opened up a year-long (1 Jan - 31 Dec 2016) analemma exposure on New Year's Day," explains Riegel. " The result is a record of the position of the sun on the hour between 7:00 am and 3:00 pm every day for a full year."
"The camera is just a light-tight box with a pinhole in the side. I put an 8x10 piece of B/W photo paper inside. The pinhole was uncovered for two minutes each hour by a rotating paper mask attached to a cheap electric clock. The image is burned into the photo paper by the bright sunlight."
" I can't claim originality for the technique, but I've only seen a couple of other similar examples done previously," says Riegel. "It's a nerve-wracking time waiting for the year to see if you set things up correctly!"
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