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Spring Equinoxes

March 20, 2011

It's been a miserable winter for parts of the country, with record-breaking snowfall creating nasty messes. Those messes may or may not be over quite yet, but at least winter is -- it ends at 6:21 p.m. Central Time today -- the vernal equinox. The Sun crosses the celestial equator from south to north, bringing more sunshine and the promise of warmer days ahead.

Other planets have their own equinoxes. That's because, like Earth, almost every other planet in the solar system is tilted on its axis. One planet is even tilted all the way over on its side.

The planet with the most dramatic looking tilt is Saturn. Its axis is tipped just a little more than Earth's is. But the planet is encircled by broad rings. So as Saturn orbits the Sun, its rings "nod" up and down as seen from here on Earth.

Saturn had its own vernal equinox in August of 2009. The rings lined up edge-on to Earth, so they formed a thin line that was barely visible. Now the rings are nodding downward, so Saturn's northern hemisphere is seeing more and more sunlight. That process will continue for another six years, with the rings tilting into better view the whole time -- making Saturn shine brighter and brighter.

The planet already shines pretty brightly right now. Look for it to the upper left of the Moon as they rise around 9 or 10 o'clock. Saturn looks like a bright golden star. The true star Spica is closer to the lower left of the Moon.

Script by Damond Benningfield, Copyright 2011


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