This week's prime sky sights are elusive but wondrous. They include a pair of planets and a pair of spacecraft.

The two brightest planets and a sliver of the moon: Observing the two most brilliant points of light in the sky - Venus and Jupiter - is not usually difficult. But this week and next, the two planets are setting so soon after the sun sets that we must look down near the horizon to spot them in the still-bright afterglow of the sun. Binoculars will almost certainly be required, even to see the brightest planet, Venus.

Why bother to search for Venus and Jupiter when they are so low in strong evening twilight? Because the two are approaching each other and next Tuesday, they will have an exceptionally close conjunction, or meeting. Furthermore, this Sunday, they are joined by a very special crescent moon - a crescent more breathtakingly slender than anyone except the most veteran moon observers has ever seen.

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On any clear day this week, you can point your binoculars down near the west-southwest horizon at about 5:50 p.m., only about 20 minutes after sunset, and try to see Venus as a fragile speck of light. Then put Venus in the lower right corner of your field of view and try to see if you can detect much dimmer Jupiter above and slightly farther left. But you should hope Sunday is clear for a glimpse of the ultra-slender moon.

The moon just after sunset Sunday is less than 20 hours past its invisible new-moon phase. If you see it, it will be an astonishing filament of light about 5 degrees, or the width of a typical pair of binoculars' field of view, to the right of the Venus-Jupiter pair. Jupiter is then almost straight above Venus and twice as close to it as the planets are to the moon.

What if Sunday is cloudy or if for other reasons, you fail to see the planets and moon? Well, on Monday, the moon will be much higher and if you look again at about 5:50 p.m., all you need to do is point your binoculars straight down from the moon to bring into sight Venus and Jupiter just above the horizon.

Spacecraft and the thin moon at dawn: Space shuttle Endeavour launched successfully at 4:14 a.m. Monday, the last night launch before NASA retires its aging orbiter fleet. Only four shuttle flights remain.

The launch of Endeavour on a 13-day mission to the international space station was delayed from Sunday to Monday due to clouds. The main goal of the mission is to add a final module, called Tranquility, to the ISS to give astronauts more room to work.

For information on how to see the shuttle and ISS pass over our sky together during some dawns this week, visit:

On Wednesday and Thursday, there is also a bonus at about 6 to 6:30 a.m. very low in the southeast: a lovely waning crescent moon.

The Associated Press contributed to this report.

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

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