Star date: 05:26:99

Breakfast with the Outer Planets

Jupiter, Saturn, Uranus and Neptune presented amateur astronomers with quite a delight over the winter in the evening sky, and this week, we may see these same outer planets in the eastern sky just before sunrise.

The Sun is currently rising about 5:30am, and so to view these planets, you will want to go outside sometime before 5 when it is still dark out. At this time, these four planets (the four largest in our solar system) will be in a line streching from the eastern horizon to about 30 degrees above the southern horizon.

The first of these we will try to view will also be the most difficult to see at this time. This is the planet Saturn. The reason it will be difficult to find will not be because it is dim. After all, Saturn is clearly visible to the naked eye, and was known to the ancients. In fact, it is so bright that at magnitude 2.1, it ranks as one of the brightest objects in the sky. The reason that Saturn will be so difficult to see this week has to do with the fact that it currently appears very close to the Sun, less than 30 degrees from our parent star. In order to see this planet and its magnificent set of rings, you will need a clear horizon to the east. Saturn will be found just 10 degrees north of east at 5am, and a little over 7 degrees above the horizon. Even with the coming daylight, Saturn should still be able to be found if your eastern horizon is low enough.

Floating in a radiant grace just 16 degrees from Saturn is the mighty king of the planets, Jupiter. Jupiter can be found less than 3 degrees south of due east, and a little over 16 degrees above the horizon. Shining at magnitude -2.2, Jupiter is over 50 times brighter than Saturn. This planet is so large that it contains more mass than all the other planets added together. The four largest moons of Jupiter (Io, Europa, Ganymede and Callisto) can be easily seen by amateur astronomers using backyard equipment. In fact, they are so easy to see that they were first discovered by the famous astronomer Galileo in the opening years of the 17th century. This was the first proof that not every object in the universe traveled around the Earth. Of course the argument was made by some for a while that although these moons revolved around Jupiter, that Jupiter was revolving aroung the Earth and so therefore, so were the moons. This argument lasted for a short while, but the discovery of the Jovian moons was among the first cracks in the armour of the theory of a geocentric, or Earth centered universe. These four moons can be seen to revolve around Jupiter over time, and their progress can be checked and recorded.

There is software and periodicals available which will list where all the moons of Jupiter are so that when you are observing this king of the planets, you can know which moon it is that you are viewing. With all the new remarkable findings from the Galileo spacecraft and other findings, it is quite a joy to know that you can actually view worlds as strange and exciting as the mysterious volcanic moon Io or the ocean covered world of Europa.

Our next target of the morning is the planet Uranus. This was the first planet discovered which was not known to ancient people, since it cannot be seen without a telescope or binoculars. Even a small pair of binoculars will reveal its bluish disk. At magnitude 5.8, Uranus can almost be seen with the naked eye under dark skies, but not quite. Look for it 68 degrees from Jupiter, hovering 13 degrees east of due south at 5am, and 32 degrees above the horizon.

Our last target of the day is the most distant of planets, Neptune. Its bluish green disk can be found just barely west of due south and 31 degrees above the horizon. It will be 12.5 degrees from Uranus, and at magnitude 7.9, it is about 7 times dimmer than Uranus.

Clear skies, and good viewing.

"Understanding is joyous" - Carl Sagan

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