Every year the pace of astronomical discovery seems to accelerate, and 2004 will maintain the trend. The next 12 months will see the culmination of some of NASA’s most audacious scientific missions. The universe around us will provide plenty of excitement, too, delivering rare spectacles such as the first passage of Venus across the sun in 122 years.
Space exploration: The first post-Columbia launch of a space shuttle, sometime after September, is sure to make headlines. More significant science will come from unmanned probes.
NASA’s Stardust spacecraft, launched five years ago, arrives at comet Wild 2 this month. And wild the encounter will be, as the probe gathers bits of comet material—the first sample from deep space—and then fires its engine to head back toward Earth. Two years from now, the payload will separate from the craft, plunge into the atmosphere, and parachute toward waiting scientists.
On January 4 and 25, two NASA rovers, Spirit and Opportunity, will land on Mars and start scooting across its rusty surface. Then in May, the Messenger spacecraft is scheduled to blast off for Mercury. Five years from now it will become the first probe to orbit that dense, pockmarked, broiling-hot planet.
By far the planet-mission headliner in 2004 will be Cassini, which reaches Saturn on July 1 after a tortuous seven-year trip past Earth, Venus, and Jupiter. Entering orbit around the ringed world, the spacecraft will drop a probe into the atmosphere of Titan, a Mercury-size moon cloaked in an opaque organic haze and possibly covered with hydrocarbon seas. Cassini will then begin a multiyear tour of Saturn and its environs.
Celestial events: For earthbound observers, 2004 offers a total lunar eclipse, visible throughout North America on October 27, and some fine shooting stars. But most of the action centers on planets, including Saturn, which makes its closest approach in decades.
Saturn reaches its peak of brightness on New Year’s Eve and remains glorious in the constellation Gemini through spring.
Mars, fading rapidly from last summer’s historic close encounter, still stands out among the dim stars of Pisces. Venus, meanwhile, grows more prominent through the first months of the year. That cloud-covered world will become unusually high and dazzling in the southwest evening sky from March until May. Venus and the crescent moon make a beautiful pairing on March 24.
Jupiter, which swallowed the Galileo spacecraft in September, rises in Leo by 10 p.m. this month and by 8 p.m. in February. In the first week of March, it reaches opposition, its closest and brightest moment of the year. It will remain, after Venus, the second-brightest object in the sky through early summer.
All five bright planets—Mercury, Venus, Mars, Jupiter, and Saturn—are visible simultaneously in the evening twilight from mid-March to early April. Mercury makes its best appearance of the year around this time. Early risers get another opportunity to see an unusual lineup when the five reappear in the predawn sky in December.
An even rarer celestial alignment takes place on June 8, when the sun will be partially eclipsed by Venus for the first time since 1882. The event, called a transit, will be visible to the naked eye—but will not be safe to watch without a professional-quality eclipse filter. It will occur at sunrise in the eastern third of the United States and Canada and at midday throughout Europe. All of North America will be able to see the next transit of Venus in 2012.
Finally, the two most reliable meteor showers—the August 11 Perseids and the December 13 Geminids—will occur under optimally dark, moonless skies. Consider it celebratory fireworks for an amazing astronomical year.