Planet Jupiter at Its Brightest in April | Almanac.com

Planet Jupiter at Its Brightest in April

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This week, the waning gibbous Moon rises an hour later each night, leaving the first part of each night black and ideal for stargazing. The first thing you see is the very brightest “star” in all the heavens—the planet Jupiter.

Jupiter came to opposition earlier this month, so it’s at its very brightest of the entire year.

Let’s be honest, though. You don’t want to fiddle with charts, and you’d like your astronomy fun and easy. Well, here it is: Just find the brightest star anytime between nightfall and midnight, and you’ll find Jupiter.

If you have a small telescope, point it there. It was Jupiter, shining brilliantly in Taurus the bull, that proved the most amazing and controversial target on January 7, 1610, when Galileo saw three stars lined up alongside the dazzling planet. By the 13th, he had watched them change position each night, spotted a fourth as well, and realized they were orbiting around that world.

This, 407 years ago, was no small event. At the time, Church doctrine followed the writings of Aristotle and Ptolemy and insisted that Earth is the center of all motion. For some bizarre reason, they’d made it into a religious principle. So Galileo enjoyed no benefits after he published his startling discovery that proved that Earth is NOT the center of all motion. Instead, those little moons whirling around Jupiter caused Galileo to be brought up on charges, forced him to recant at penalty of being burned at the stake, and left him to die penniless. 

But fast forward to our modern times, and now those four giant moons visible through the smallest cheap telescope are called “the Galilean satellites.” So it all worked out for the bearded, cantankerous Italian, or at least for his disembodied spirit.

There’s a bonus! Directly below Jupiter floats a distinctly blue star. In fact, it’s the bluest bright star in our sky. This is Virgo’s “Alpha” star, Spica (“SPY-ka”). Located a whopping 260 light-years away, it’s the 14th brightest star in our sky. Together with orange Arcturus, far to Jupiter’s left, it’s a traditional sign of spring.

And just as spring colors are returning to nature on the ground around us, it’s fun to compare Jupiter’s yellow-whiteness with the pumpkin hue of Arcturus and the sapphire blueness of Spica.

See more of This Week’s Amazing Sky.

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