The sun is showing signs of perking up lately, which for one thing means it’s getting warmer, thankfully.

The sun is getting higher in the sky as the Earth, which is tilted by 23.5 degrees, swings us Northerners back more directly into its rays. Not only that, but sunspots are reappearing after a prolonged minimum in their 11-year cycle that had the solar astronomers wondering what their absence signified about the workings of the sun. Sunspots showed up every day in February, in contrast to 2009 when unexpectedly there were none at all on 260 days.

The warmer days, luckily, regenerate reliably according to plan. Also according to plan is an annual Earth occurrence that fascinates and partly stumps the astronomers. The less they understand something, the more it fascinates them, it seems. In this I feel connected to them.

Around the vernal equinox (March 20 this year), auroras start firing more intensely in the northern sky.

I’ve stood on the edge of a field in Troy in past years and watched them fill the sky — huge snakes of polar green kindling like ice and fire between me and the Big Dipper. They twist and seem to shimmer with blue and violet tinges, then fade away like thoughts. Then re-emerge. The farther north you go, the brighter and more enormous they are. You can only think how the imagination of an ancient Abenaki Indian standing in a clearing might have been struck by the huge cloud mountains running like water through waves of light. What did they signify?

Nowadays we explain the auroras like this: The sun generates streams of electrically charged atomic particles called the solar wind. Some of the particles moving us-ward get trapped in the Earth’s magnetic field, and they tend to flow toward the poles. There, they interact with other particles, energy is released, and arcs of green light, stupendous to our eyes, slowly bend and twist across the sky.

Around the vernal equinox, when the Northern Hemisphere has reached the halfway point between its full tilt away from the sun in December and its full tilt toward the sun in June, the auroras intensify. The scientists do not know why, exactly. It has nothing to do with temperatures. It’s thought that “ropelike magnetic connec-tions” develop along the angle between the Earth and sun, and more charged particles travel along those connections and channel toward the magnetic pole. In turn, the northern lights intensify.

On the sun, flares, prominences and ejections of material which amount to colossal explosions take place pretty frequently. Some of them are associated with sunspots, and sometimes the explosions are so huge they disrupt radios and electric grids on Earth. Their causes are not understood well enough to predict when they’re going to happen in most cases. This spring, though, right on schedule, the space weatherologists have been reporting that the solar wind is picking up, meaning more auroras with brighter “auroral substorms” should be generated soon, right on cue.

The sun and Earth have invisible connections; this much is known. Some of those connections make themselves known from time to time as tremendous green serpents of light in the sky. And those connections intensify — for reasons not fully understood — just when spring and winter are haggling over March, which is the tip-ping point toward summer. They’re a sign summer will soon blaze up, as quick as a straw fire, or as an auroral substorm, or as a thought. Afterward come the auroras of autumn. What significance this has, exactly, I have no idea. The sky’s the limit.

naturalist@dwildepress.net