Montana Earth Science Picture of the Week

You can see what Galileo saw.
Photo courtesy of Mark's Amateur Astronomy Pictures Page

Grab your binoculars. . .
Many of those bright points of light that we call "stars" are not stars at all. Some are planets, many are distant galaxies, and others are clouds of gas and dust called nebulae (plural for nebula). When this picture was posted in March of 2004, it was an especially good time to see Jupiter. October and November of 2011 provide another great opportunity to see the gas giant. With a telescope you can clearly see Jupiter and some of its moons, which were discovered by Galileo in 1610. In spring of 2004 Jupiter was often the brightest object in the eastern night sky. That's the case again this fall (2011), and if you don't have a telescope you don't need to miss out . . . Jupiter and some of its moons are easily visible with a quality pair of binoculars. The moons don't look as big as they are in the image on the right, but you can seen them

CLICK HERE to find out what you can see.

Why October and November 2011? . . .
On October 29, 2011 the planet Jupiter will be lined up with the Earth and the Sun (Sun, Earth, Jupiter). Because it will be opposite the sun, astronomers say that Jupiter is in "opposition" to the Sun. As a result, Jupiter is visible all night, rising in the east as the Sun went down, and then setting in the west as the Sun came up the next morning. On the other hand, when the Earth and Jupiter are on different sides of the Sun, Jupiter cannot be seen for months.

To find our where the planets are in relationship to the Sun (and each other), CLICK HERE, set the "size" at 800, and then select "update".

Galileo rocked the boat . . .
Upon hearing at age 40 that a Dutch optician had invented a glass that made distant objects appear larger, Galileo crafted a telescope and began to look at the heavens. Although it is now known that Jupiter has over 60 moons, Galileo was the first to report seeing the four larger ones (shown in above photo) in 1610. This, along with other discoveries made by Galileo, revolutionized astronomy and challenged some of the religious and philosophical views of the time. His discovery that Jupiter is orbited by moons contradicted the geocentric theory, which held that the Earth was the only center of motion in the universe. With his telescope, Galileo also found that Venus went through phases like our Moon; a phenomenon that could not be explained in terms of an Earth-centered system. Furthermore, his discovery of sunspots showed that it had "blemishes," countering the Aristotelian view that the Sun was perfect. In his old age Galileo was forced by The Inquisition to recant his belief in the Copernican (heliocentric) Theory that the planets orbit around the Sun.

Term: The Inquisition, heretic (Define one of these in your own words!)


Montana's Earth Science Pictures

By Rod Benson
Earth Science Teacher at Helena High School

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