Four hundred years ago from Jan. 7 and 8, Galileo first had clear views of the four biggest and bright moons of Jupiter, later named the Galilean moons. If you have a telescope and can find Jupiter - the brightest light in the southwest sky at nightfall - you can recreate Galileo's great sightings.

If you do not have a telescope, fortunately, there are many other interesting astronomy sights to look for this week.

The moon and Jupiter: You can spot, very low near the southeast horizon, the very thin moon just 30 to 45 minutes before sunrise Wednesday morning. An easier observation is a slender lunar crescent very low in the west-southwest sky about 45 to 60 minutes after sunset Saturday.

On Sunday, look to the southwest at nightfall for a thicker crescent moon hanging not too far to the lower right of Jupiter's bright point of light. Last but not least, if the sky on Monday is clear, you can see the moon shining almost directly above Jupiter.

By the way, the brightest planet, Venus, was exactly on the far side of the sun from us yesterday. Not until next month will Venus start emerging into view, very low in the west. When it does, however, there will be a chance to make a challenging but amazing observation of Venus and Jupiter extremely close together in the bright dusk.

The red planet and the red supergiant star: Mars is often called the "Red Planet," although it really looks more like an orange-yellow spark of campfire in our sky when it is near and bright - as it is now. You cannot miss it, rising brighter than anything else in the eastern sky between 6 and 7 p.m. this week.

The planet is not quite as bright as Sirius, the blue-white star that is the brightest of all stars and twinkles in the southeast sky, unlike the steady-shining Mars. But if you look well to the upper right of Sirius, you'll see Orion's belt of three stars in a row. And to upper left from the belt, about one fist-width at arm's length, you will see the brightest star that is orange-yellow: Betelgeuse.

Betelgeuse usually outshines Mars, but with Earth only two weeks away from its closest approach to Mars until 2014, the planet is much brighter. Betelgeuse is fascinating in its own right, however. This star is a red supergiant so big that if we replaced our own sun with it, Betelgeuse would fill our solar system out to beyond the orbit of Mars.

Surprise fireballs: You never know when a "fireball" - a meteor even brighter than Jupiter or Venus - may blaze across the sky.

Two readers recently saw fireballs. At about 10:21 p.m. Dec. 23, Rick McGuire, of Linwood, saw a brilliant orange meteor glide to the lower left and burn out at the feet of Orion, which lasted for about 5 to 7 seconds. At 7:40 p.m. Dec. 28, Roger Linton saw a bright meteor zoom across the southern sky and actually disappear below the eastern horizon.

Fred Schaaf is a local author and astronomer. He can be reached at: