WASHINGTON -- Astronomers announced Wednesday they had discovered what could be the first planet outside Earth's solar system, a mysterious world that appears to be orbiting the flashing remains of a collapsed star.
'It's not 100 percent sure they're right, but if they are it's trailblazing and historic,' said Cornell University astronomer Carl Sagan.
Although scientists have long thought other planets exist elsewhere in the universe, the discovery could end the long hunt and provide new reason to believe that extraterrestrial life may be possible, the researchers said.
'It's the first concrete evidence that there may be other planetary systems other than our own in the universe. Ours could have just been a fluke. But if we see other planets it means our star is not alone in having a planetary system,' said Andrew Lyne, who led the British team that found the possible planet.
'If there are other planetary systems then it means that there are other possible platforms for life in the universe. Planets are about the only place in the universe that we think that life could exist in any form that we could imagine,' he said in a telephone interview.
Lyne said he doubted life existed on the newly discovered planet because any living organisms would probably have been destroyed when its sun collapsed in a massive nuclear explosion.
In addition, its sun -- a pulsar -- emits most of its energy in the form of deadly gamma ray radiation, which would constantly bathe any planet and kill any life, Lyne said.
However, he added that there is a remote possibility the planet was formed after the sun collapsed, or it could have some type of atmosphere that could protect life.
If it has an atmosphere, the gamma rays from the star probably produce a constant light show similar to Earth's northern lights as gamma rays hit the atmosphere every third of a second, he said.
Other astronomers, however, remained skeptical, saying more research had to be conducted before anyone could conclude the researchers had in fact discovered a planet.
'It's the Holy Grail of astronomy -- to find a new planet. There have been a number of announcements that have all turned out to be either premature or incorrect,' said NASA astronomer Stephen Maran. 'The question is, is this more of the same or is this the breakthrough we're all waiting for?'
Sagan said there was about a 50-50 chance that the body would turn out actually to be a planet. If true, the discovery raises a host of questions about how planets and pulsars form, Sagan said in a telephone interview.
The search for other planets and other solar systems has been difficult because telescopes on Earth are not powerful enough to detect relatively small planets circling much brighter stars that are so far away it takes light, traveling at 186,000 miles per second, years to reach Earth.
In the new report in the British journal Nature, Lyne and colleagues used a radio telescope at the Nuffield Radio Astronomy Laboratories of the University of Manchester in Cheshire, Britain, to study a star known as pulsar 1829-10.
When the cores of massive stars exhaust their nuclear fuel, outward radiation can no longer offset the inward pull of gravity. As a result, such stars can suddenly collapse and explode, leaving a small core just a few miles across that is so dense normal atoms are crushed into a sphere of uncharged neutrons.
Spinning neutron stars are called pulsars because they emit regular flashes of radiation as they spin about in the depths of space like cosmic lighthouses.
In 1985, Lyne and his colleagues discovered the pulsar about 30,000 light years from our solar system near the center of the Milky Way. A light year, the distance light travels in a year, is about 6 trillion miles.
The researchers have been studying the radio signals it emits and intensified their observations in an attempt to understand what appeared to be an irregularity in its pulse every six months. About six weeks ago, the astronomers began to suspect that the irregularity was caused by the gravitational pull of an orbiting body.
'It took a few days to dawn on us. We were worried there might be something wrong with our equipment,' Lyne said. 'But we were very excited when we realized what this implied.'
After accounting for other possible explanations, the scientists concluded the oscillation was caused by a planet orbiting the star in a highly circular orbit every six months.
The planet appears to be about twice the diameter and 10 times the mass of Earth and is about the same distance from its sun as Venus is from our sun.
The astronomers are continuing to study the pulsar to learn more about the possible planet and determine whether there are any other planets orbiting the star, Lyne said.
'There's an indication in our data of some effects that could be attributable to other planets. They would be further away from the star, ' he said.
In an article accompanying the new report, David Black of the Lunar and Planetary Institute in Houston, said that if the planet is confirmed it could challenge existing theories about planet and pulsar formation.