As some of us stood amazed at the haphazard dance of northern lights last Saturday night, a team of scientists and graduate students from New Hampshire’s Space Science Center watched with equal amazement night as a rocket laden with sensors arced 200 miles into the sky over the Poker Flat Research Range in Fairbanks, Alaska. Its purpose – to learn how Earth’s magnetic bubble (magnetosphere) couples with the upper atmosphere to deliver displays of the northern lights.
Instruments on board sampled changes in the magnetic and electric fields stimulated by a barrage of electrically charged particles streaming into Earth’s ionosphere from the sun. Scientists hope the information gathered and relayed back to the ground station will help them better understand magnetic waves called Alfvén waves in our upper atmosphere. The waves are thought to be the driving force in the creation of the thick arcs of northern lights often seen spanning the northern sky from east to west during auroral displays. We saw some of these arcs in last Saturday’s aurora.
According to Marc Lessard, an associate professor at the UNH Institute for the Study of Earth, Oceans, and Space (EOS) and department of physics, the Alfvén resonator is a channel in the ionosphere several hundred miles tall and only about six miles wide that acts like a guitar string when “plucked” by energy delivered by the solar wind to Earth’s magnetosphere high above. It’s thought that electrons from the sun’s solar wind (or delivered by flare or coronal mass ejection) are pumped into the channel to create a column of aurora. Complicated physics for sure.
We’ve come a long way since the days when people once thought the aurora was sunlight reflecting off polar ice!
In other news, a meteor flared over Huangzhong County, Qinghai Province, China on the afternoon of Saturday February 11 leaving several meteorites scattered across the landscape and gouging out at least two small craters. To date four pieces have been recovered. The largest, weighing over 25 lbs., fell on a snowy mountaintop. Clicking on the picture above will take you to an excellent report on the fall by a Chinese TV station.
Take a good look at the fresh meteorite. It’s very typical – pale, cement-like interior with a matte-black fusion crust of melted rock from its high speed burn through the atmosphere. From the appearance alone, the new Chinese meteorite looks like a very primitive but common type of stony chondrite from the outer crust of an asteroid. For photos of some of the smaller pieces and villagers searching for more, click HERE.
By the way, did you see the partial eclipse of the sun earlier today? No? Neither did I, since the eclipse wasn’t visible from the ground, but NASA’s Solar Dynamics Observatory did from geosynchronous orbit some 22, 369 miles away. That can only mean that today is new moon. Watch for the moon to scoot away from the sun and return to the evening sky tomorrow.