Astronomers have discovered a planet orbiting the
star Epsilon Eridani.
The relative proximity to Earth - just 10.5 light years
away - means this is the closest star yet to have a planet
found circling about it.
This raises the exciting possibility that the Hubble
Space Telescope may be able to obtain an image of the
planet.
Were this to happen, it would be an astronomical
landmark as it would be the first planet actually seen
circling another star.
The discovery will be announced at the International
Astronomical Union's General Assembly in Manchester, UK,
on Monday.
Larger than Jupiter
The planet orbiting Epsilon Eridani, a star very
similar to our own Sun, was found by a team led by Dr
William Cochran, of the University of Texas McDonald
Observatory.
The planet orbits Epsilon Eridani from a distance of
about 500m km (300m miles) - roughly the distance from the
Sun to the asteroid belt in our own Solar System.
Researchers estimate that the planet is probably just
larger than Jupiter, the largest planet in our Solar
System.
Epsilon Eridani is a star slightly less massive than
our Sun and slightly cooler.
It is most probably younger as well, being only about
one billion years old compared with our Sun's age of 4.5bn
years.
Earth-sized planets
Dr Cochran said of the discovery "is like finding a
planet in our own backyard, relatively speaking."
"Not only is this planet nearby, it lies 478 million
kilometers (297 million miles) from its central star,"
Cochran said.
"Having a large planet orbiting a fair way out from
Epsilon Eridani means there could be room for Earth-like
planets in a reasonably stable orbit closer into the star.
"All the planets found so far that are the size of
Jupiter are much closer to the parent star."
Viewed from Earth
It may be possible to view the new exoplanet with the
Hubble Space Telescope or with the new generation of
advanced imaging systems connected to ground-based
telescopes.
If the planet could be seen as a tiny speck of light
next to the artificially suppressed image of its parent
star, it would be a major scientific achievement - the
first time an image of a planet circling another star
would have been obtained.
With such an image, astronomers could analyse the light
from the planet and determine its physical characteristics
and composition.
To date, current imaging technology has forced
astronomers to use indirect methods to detect the presence
of planets around stars. This can involve looking for a
tell-tale "wobble" in the parent star - behavior that can
be explained only by the gravitational effects associated
with a planet-sized body circling nearby.
