SOMETHING SPECIAL ABOUT MARCH: If you feel like March has been a good month for auroras ... you're right. According to 75 years of historical records analyzed by solar physicist David Hathaway, the months around equinoxes are almost twice as likely as solstices to have geomagnetic disturbances. Indeed, according to this plot, March may be the best month of the year for Arctic auroras:
Photo credit: Caroline/AdventureMutzz of Ersfjordbotn, Norway. Mar. 8, 2017
Researchers have long known that auroras favor equinoxes, but they didn't fully understand why until NASA launched the THEMIS satellites 10 years ago. In 2007, THEMIS detected magnetic 'ropes' occasionally connecting Earth's upper atmosphere directly to the sun. Solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras.
It turns out that rope-like magnetic connections between the sun and Earth are favored in spring and fall. It's a matter of geometry: As Earth goes around in its orbit, Earth's tilted magnetic poles make different angles with respect to the Sun, tipping back and forth with a one-year cadence. Around the time of the equinoxes, Earth's magnetic field is best oriented for "connecting-up" with the sun.
Northern spring is coming. Arctic sky watchers, enjoy the green!
THE TRANSFORMATION OF VENUS: On March 25th, Venus will pass almost directly between Earth and the sun--an event astronomers call "inferior solar conjunction." As Venus approaches the sun, the planet is turning its night side toward Earth, reducing its luminous glow to a thin sliver. Astrophotographer Raffaello Lena of Rome, Italy, has been monitoring the transformation:
"The progression of the crescent as Venus approaches inferior conjunction is clear," says Lena. "I took these pictures using an 18 cm (7 inch) Mak Cassegrain telescope."
You don't need such a large telescope, however, to see the shape of Venus. Even ordinary binoculars will show the crescent. Amateur astronomers are encouraged to monitor Venus in the lead-up to inferior conjunction. In the nights ahead, the crescent of Venus will become increasingly thin and circular. The horns of the crescent might actually touch when the Venus-sun angle is least on March 25th.
Look for Venus shining brightly in the western sky at sunset--you can't miss it!
NORTHERN LIGHTS SPACE PENDANT: To raise money for their trip to the Arctic Circle, on March 2nd the students of Earth to Sky Calculus flew a payload-full of Northern Lights pendants to the edge of space above California. You can have one for $69.95. Each piece of jewelry comes with a greeting card telling the story of the pendant's trip to the stratosphere and certifying its peak altitude: 112,200 feet above Earth's surface.
Bonus: Would you like your pendant to fly above the Arctic Circle as well? Make a note in the COMMENTS box at checkout and we will take your pendant to Sweden for a second trip to the stratosphere.
More far-out gifts may be found in the Earth to Sky Store. All proceeds support STEM education and high-altitude ballooning.
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