Early-morning joggers, dog-walkers and commuters are enjoying a dazzling pre-dawn light show in the eastern sky this week.
Jupiter and Venus, the two brightest planets visible to the naked eye, are converging on each other in a dramatic conjunction that will only get better next week.
"It's pretty spectacular," said Jim O'Leary, director of the Maryland Science Center's Davis Planetarium. "It reminds you of the ancients and their mythology, and how they referred to the planets as gods because they could easily wander the sky."
"A conjunction like this was always a momentous gathering of the gods in the sky," he said. "It's sort of a neat connection to our ancestors."
The two planets appeared less than a degree apart this morning, about the width of a full moon.
It's an optical illusion, of course. Venus, the brighter object of the pair, is actually 118 million miles away. Jupiter is almost five times as distant -- about 580 million miles away, and on the far side of the solar system. It appears so bright only because it is so much larger than Venus.
Each morning in the coming days, Venus will move lower in the sky, widening its apparent distance from Jupiter. But the sky show will get even better Tuesday morning, when the waning crescent moon joins the two planets in the pre-dawn sky. "Early risers should notice it," O'Leary said.
Such close conjunctions of Jupiter and Venus occur at regular intervals. They cluster in morning-and-evening pairs about once every 2 1/2 years.
This week's conjunction will be followed by its evening counterpart in the western sky on Sept. 2. The two planets will converge again in February and December 2008, and then in May 2011 and March 2012.
The current conjunction, in addition to being an unusually close pairing of the two planets, has one added bonus, O'Leary said. Tuesday morning, when the crescent moon joins the two planets in the eastern sky, it will actually pass directly in front of Jupiter, blocking it from view for 63 minutes beginning at 11:08 a.m.
Because this "occultation" will occur in the daylight hours in Maryland, however, it won't be visible without a telescope.
Weather permitting, O'Leary said, the Davis Planetarium will train its observatory telescopes on the moon and transmit video images of the occultation of Jupiter to visitors in the Science Center's SpaceLink gallery.
Information: http://science. nasa.gov/headlines.