The apparent motion of the sun around the sky is really a reflection of Earth’s yearly cycle around the sun. The seesaw-like up-and-down movement of the sun from season to season is caused by Earth’s titled axis and our planet’s changing orientation to the sun during the year. Credit: Thomas G. Andrews / NOAA

Perihelion Paradox? Closer Sun, Colder Days

Yesterday, while preparing dinner, Earth reached its closest point to the sun for the year. This annual milestone, called perihelion, from the Greek ‘peri’ (close) and ‘helios’ (sun), happens paradoxically every January. Shouldn’t it be warmer if we’re closer to the sun? Earth’s distance from the sun varies over the course of a year because we…
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Sun SDO combo UV Dec28_2015FEA

Aurora May Drop By Your New Year’s Eve Party

Big sunspot group 2473 cut loose a long-lasting M-class flare earlier today. The explosion produced a fast-moving bubble of plasma directed toward Earth. Plasma, a hot mix of negatively-charged electrons and positively-charged ions (atoms that have lost an electron) may look like a gas but it behaves differently enough to be considered its own state of…
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Winter season Orion with snow pines FEA

Happy Winter Solstice As We Arrive At The Longest Night Of The Year

Each of us senses the flow of time differently. For me, December’s gone by quickly. For you, maybe not. Either way, we’ve arrived at the start of winter or the winter solstice. At precisely 10:48 p.m. CST (11:48 p.m. EST, 9:48 p.m. MDT, 8:48 p.m. PST) Monday Dec. 21st, the sun will reach its lowest point…
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A few more images of the pellet-shaped 2003 SD220 from Arecibo Observatory. Some online reports are suggesting the asteroid could cause earthquakes. Asteroids can't and don't do this, unless a large one happens to hit Earth. This will pass over 6 million miles from us. No worries. Credit: NASA/NSF

Auroral Alert Tonight Dec. 18-19 / Holiday Asteroid Parade

Keep watch on the northern sky tonight. Several recent solar blasts are working their way toward Earth as you read this. Expect the bee-like swarm of subatomic particles to buzz past the planet and possibly link into out magnetic domain by late afternoon. Minor (G1) storming is expected during the early evening hours over the U.S.…
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As a display evolves, rays often grow from the arcs, stretching upwards while flickering and moving along the band. Credit: Bob King

Auroras May Bloom Dec. 6-8

With the moon dwindling to a crescent, conditions look great for northern lights viewing. Good thing because minor G1 storms are forecast for late tonight Dec. 5th through Sunday morning (Dec. 6) and continuing through dawn. After a daytime lull, G1 conditions recur from 9 p.m. till midnight Sunday night (Dec. 6) and Monday night, Dec. 7 during the…
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