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Moons of Galileo

In History by Brian Koberlein0 Comments

In the first few months of 1610, Galileo Galilei pointed a small twenty-power telescope at Jupiter. What he observed changed the way we understood the universe.

With his telescope, Galileo saw what appeared to be three faint stars in a straight line near Jupiter. The next evening he saw what appeared to be the same three stars, but it seemed Jupiter had moved in the opposite direction to its expected motion. Within a few days it became clear that Galileo wasn’t observing the motion of Jupiter relative to some faint stars, but rather these stars were moving along with Jupiter.

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Spot On

In Solar System by Brian Koberlein2 Comments

In 1665 Gian Domenico Cassini observed a feature on Jupiter. It was described as an oval about 1/7 the width of the planet itself, and since it appeared reddish in color it became known as the Great Red Spot. Since then the spot has been observed over the years by both professional and amateur astronomers. It has been Jupiter’s most prominent feature for nearly four centuries.

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Good to be the King

In Solar System by Brian Koberlein0 Comments

Jupiter is sometimes said to be a failed star, with a mass just a bit too small to fuse elements in its core. This isn’t really an accurate description, since the it takes at least 13 times the mass of Jupiter to initiate fusion. However, when compared to the other planets in the solar system, Jupiter is king. Jupiter is 2.5 times the mass of all the other planets combined.

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Rocking Asteroids

In Asteroids by Brian Koberlein2 Comments

There are a lot of rocks in the asteroid belt of our solar system. One of the most current asteroid databases lists the orbital parameters of almost 370,000 asteroids. Most of these orbit at an average distance of about 2 AU to 3.5 AU. (An AU, or astronomical unit, is roughly the distance of the Earth from the Sun).

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Whistlers

In Radio Astronomy by Brian Koberlein0 Comments

When radio waves travel through the ionosphere, lower frequency waves travel more slowly than higher frequency ones. This can create an effect with radio signals known as whistlers.