Mercury Planet

It is the closest planet to the sun. A roasting crisp of a world where daytime temperatures reach 800 degrees. And yet, stretched across the surface of Mercury are what look to be patches of ice. It's one of the biggest mysteries of this little planet--a bookend of the solar system and one of our nearest neighbors. While Mercury was visited briefly once, by Mariner 10 in the mid-1970s, less than half of the planet was seen by the spacecraft's cameras.

Scientists poring over their first close-up data from Mercury in almost 33 years say they're delighted by some new discoveries and astonished by the remarkably sharp view of the planet captured by NASA's Messenger spacecraft during its flyby earlier this week. "We're just jumping up and down as each new image gets examined and new data comes down," said Messenger's principal investigator, Sean Solomon of the Carnegie Institution in Washington.

Researchers have cracked a mystery at the core of Mercury -- and say there's molten fluid inside the tiny planet. The finding, reported Friday in the journal Science, helps explain the discovery decades ago that Mercury has a small magnetic field. The discovery by the Mariner 10 spacecraft puzzled scientists, who believed that because of its small size the planet's core had long ago solidified.

Researchers have cracked a mystery at the core of Mercury -- and say there's molten fluid inside the tiny planet. The finding, reported Friday in the journal Science, helps explain the discovery decades ago that Mercury has a small magnetic field. The discovery by the Mariner 10 spacecraft puzzled scientists, who believed that because of its small size the planet's core had long ago solidified.

Japan and the European Space Agency are planning a joint mission that would be the first to land a probe on Mercury. Three probes would map the topography and study the origins of the closest planet to the sun. Russian Soyuz rockets are expected to launch the probes starting in 2010. They would reach Mercury about four years later, with one probe landing on the planet and the other two orbiting and charting its surface for a year.

Scientists poring over their first close-up data from Mercury in almost 33 years say they're delighted by some new discoveries and astonished by the remarkably sharp view of the planet captured by NASA's Messenger spacecraft during its flyby earlier this week. "We're just jumping up and down as each new image gets examined and new data comes down," said Messenger's principal investigator, Sean Solomon of the Carnegie Institution in Washington.

Mercury makes a rare appearance in the evening sky. Look for it during evening twilight at about 8:40 in line with the crescent moon and Venus, and almost twice as far from Venus as Venus is from the moon. Use binoculars. This little planet stays near the sun and is never visible very late into the evening. Mercury is 12 degrees high at 8:40 and sets at 9:45. It remains visible through the end of the month. * Source: John Mosley, Griffith Observatory

Mercury will transit, or pass across the face of, the sun Wednesday, an event that happens about 12 times per century. Because the planet is so small compared with the sun, it will appear only 0.5% as wide. But observers using a small telescope equipped with a solar filter should find Mercury's dark profile readily distinguishable from lighter sunspots. The transit begins at 11:12 a.m. PST and can be viewed live online at www.exploratorium.edu/transit.

Scientists probing Mercury's surface with radio waves now believe that the closest planet to the sun has a hot equator but no internal heat source, as previously thought. They have no clues as to what makes up the interior of Mercury. Last year, the astronomers, from the University of New Mexico and the Los Alamos National Laboratory, probed Mercury with radio wave-emitting equipment. They found that Mercury's erratic orbit, which swings it from 28.5 million miles to 43.

New evidence suggests Mercury has a north pole ice cap formed by "snow" on the planet closest to the sun, according to findings presented last week by scientists surprised by their own discovery. "The general reaction . . . was 'Oh, my God, that can't be ice, can it?' " said Caltech planetary scientist Duane Muhleman at a meeting of the American Astronomical Society in San Francisco. "But once you think about it and do the analysis it makes perfect sense."

Mercury will transit, or pass across the face of, the sun Wednesday, an event that happens about 12 times per century. Because the planet is so small compared with the sun, it will appear only 0.5% as wide. But observers using a small telescope equipped with a solar filter should find Mercury's dark profile readily distinguishable from lighter sunspots. The transit begins at 11:12 a.m. PST and can be viewed live online at www.exploratorium.edu/transit.

NASA's Messenger probe began its seven-year journey to Mercury early Tuesday, blasting off from Cape Canaveral, Fla., at 2:16 a.m. after a day's delay caused by Tropical Storm Alex. Alex cleared the cape area about an hour before the scheduled liftoff, allowing the 1.2-ton craft to begin its voyage after shedding the last stage of its Delta launch vehicle.

NASA's Messenger spacecraft is scheduled to launch Sunday on a 5-billion-mile trip to Mercury -- the first visit in 30 years to the most extreme and least studied of the inner planets. It will take seven years for the $427-million probe to reach Mercury, the closest planet to the sun.

Japan and the European Space Agency are planning a joint mission that would be the first to land a probe on Mercury. Three probes would map the topography and study the origins of the closest planet to the sun. Russian Soyuz rockets are expected to launch the probes starting in 2010. They would reach Mercury about four years later, with one probe landing on the planet and the other two orbiting and charting its surface for a year.

It is the closest planet to the sun. A roasting crisp of a world where daytime temperatures reach 800 degrees. And yet, stretched across the surface of Mercury are what look to be patches of ice. It's one of the biggest mysteries of this little planet--a bookend of the solar system and one of our nearest neighbors. While Mercury was visited briefly once, by Mariner 10 in the mid-1970s, less than half of the planet was seen by the spacecraft's cameras.

On Monday, Los Angeles residents will have their first chance since 1960 to see the innermost planet of the solar system silhouetted against the face of the sun, a rare event known as a transit of Mercury. The next one visible in Los Angeles will be Nov. 8, 2006. From 1:11 to 2:20 p.m., Mercury will pass just inside the northern edge of the sun's disk. Do not look directly at it, however. The transit should be observed by the same techniques used for viewing a solar eclipse.

NASA's Messenger spacecraft is scheduled to launch Sunday on a 5-billion-mile trip to Mercury -- the first visit in 30 years to the most extreme and least studied of the inner planets. It will take seven years for the $427-million probe to reach Mercury, the closest planet to the sun.

On Monday, Los Angeles residents will have their first chance since 1960 to see the innermost planet of the solar system silhouetted against the face of the sun, a rare event known as a transit of Mercury. The next one visible in Los Angeles will be Nov. 8, 2006. From 1:11 to 2:20 p.m., Mercury will pass just inside the northern edge of the sun's disk. Do not look directly at it, however. The transit should be observed by the same techniques used for viewing a solar eclipse.

Mercury makes a rare appearance in the evening sky. Look for it during evening twilight at about 8:40 in line with the crescent moon and Venus, and almost twice as far from Venus as Venus is from the moon. Use binoculars. This little planet stays near the sun and is never visible very late into the evening. Mercury is 12 degrees high at 8:40 and sets at 9:45. It remains visible through the end of the month. * Source: John Mosley, Griffith Observatory

Astronomers taking a closer look at Mercury, the nearest planet to the sun, have confirmed the existence of frozen water in an arid, airless land where daylight is hot enough to melt lead. The planet's lakes of ice, cupped in polar craters miles across and shielded by constant shadows, may be millions of years old, said researchers at the Jet Propulsion Laboratory and the National Astronomy Center at Arecibo, Puerto Rico.