Montana Earth Science Picture of the Week

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, was an especially good time to take a look at Jupiter. With a telescope you would have clearly seen Jupiter and some of its moons, which were discovered by Galileo in 1610. Jupiter is often the brightest object in the eastern night sky, and that was the case in March of 2004. If you didn’t have a telescope, you didn’t have to miss out . . . Jupiter and some of its moons were easily visible with a quality pair of binoculars. The moons didn't look as big as they are in the image on the right, but you would have seen them

Why that week? . . .
On March 3, 2004 around 10 p.m. MST the planet Jupiter was lined up with the Earth and the Sun (Sun, Earth, Jupiter). Because it was opposite the sun, astronomers say that Jupiter was in "opposition" to the Sun. As a result, Jupiter was 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. But that wasn't the case in March of 2004. In fact, Jupiter’s opposition to the Sun that spring also happened at a time when it was as close as it ever gets to the Earth, further enhancing our view of the gas giant.

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 recant his belief in the Copernican (heliocentric) Theory that the planets orbit around the Sun.

Term: The Inquisition