Astronomers find 'home from home' - 90 light years away!
Particle Physics and Astronomy Research Council (PPARC)
July 3, 2003
Astronomers looking for planetary systems that resemble our own solar
system have found the most similar formation so far. British
astronomers, working with Australian and American colleagues, have
discovered a planet like Jupiter in orbit round a nearby star that is
very like our own Sun. Among the hundred found so far, this system is
the one most similar to our Solar System. The planet's orbit is like
that of Jupiter in our own Solar System, especially as it is nearly
circular and there are no bigger planets closer in to its star.
"This planet is going round in a nearly circular orbit three-fifths the
size of our own Jupiter. This is the closest we have yet got to a real
Solar System-like planet, and advances our search for systems that are
even more like our own," said UK team leader Hugh Jones of Liverpool
John Moores University.
The planet was discovered using the 3.9-metre Anglo-Australian
Telescope [AAT] in New South Wales, Australia. The discovery, which is
part of a large search for solar systems that resemble our own, will be
announced today (Thursday, July 3rd 2003) by Hugh Jones (Liverpool John
Moores University) at a conference on "Extrasolar Planets: Today and
Tomorrow" in Paris, France.
"It is the exquisite precision of our measurements that lets us search
for these Jupiters - they are harder to find than the more exotic
planets found so far. Perhaps most stars will be shown to have planets
like our own Solar System", said Dr Alan Penny, from the Rutherford
The new planet, which has a mass about twice that of Jupiter, circles
its star (HD70642) about every six years. HD70642 can be found in the
constellation Puppis and is about 90 light years away from Earth. The
planet is 3.3 times further from its star as the Earth is from the Sun
(about halfway between Mars and Jupiter if it were in our own system).
The long-term goal of this programme is the detection of true analogues
to the Solar System: planetary systems with giant planets in long
circular orbits and small rocky planets on shorter circular orbits.
This discovery of a -Jupiter- like gas giant planet around a nearby
star is a step toward this goal. The discovery of other such planets
and planetary satellites within the next decade will help astronomers
assess the Solar System's place in the galaxy and whether planetary
systems like our own are common or rare.
Prior to the discovery of extrasolar planets, planetary systems were
generally predicted to be similar to the Solar System - giant planets
orbiting beyond 4 Earth-Sun distances in circular orbits, and
terrestrial mass planets in inner orbits. The danger of using
theoretical ideas to extrapolate from just one example - our own Solar
System - has been shown by the extrasolar planetary systems now known
to exist which have very different properties. Planetary systems are
much more diverse than ever imagined.
However these new planets have only been found around one-tenth of
stars where they were looked for. It is possible that the
harder-to-find very Solar System-like planets do exist around most
The vast majority of the presently known extrasolar planets lie in
elliptical orbits, which would preclude the existence of habitable
terrestrial planets. Previously, the only gas giant found to orbit
beyond 3 Earth-Sun distances in a near circular orbit was the outer
planet of the 47 Ursa Majoris system - a system which also includes an
inner gas giant at 2 Earth-Sun distances (unlike the Solar System).
This discovery of a 3.3 Earth-Sun distance planet in a near circular
orbit around a Sun-like star bears the closest likeness to our Solar
System found to date and demonstrates our searches are precise enough
to find Jupiter- like planets in Jupiter-like orbit.
To find evidence of planets, the astronomers use a high- precision
technique developed by Paul Butler of the Carnegie Institute of
Washington and Geoff Marcy of the University of California at Berkeley
to measure how much a star "wobbles" in space as it is affected by a
planet's gravity. As an unseen planet orbits a distant star, the
gravitational pull causes the star to move back and forth in space.
That wobble can be detected by the 'Doppler shifting' it causes in the
star's light. This discovery demonstrates that the long term precision
of the team's technique is 3 metres per second (7mph) making the
Anglo-Australian Planet Search at least as precise as any of the many
planet search projects underway.
Notes for Editors:
The team is supported by the UK Particle Physics and Astronomy Research
Council, the Australian government and the US National Science
Dr Hugh Jones will be presenting details of the new planet on 3 July at
the "Extrasolar Planets: Today and Tomorrow" conference in Paris. The
conference will be web-streamed live from www.canalu.fr.The
describing the new planet has been accepted for publication by the
Astrophysical Journal Letters.
Images are available to download from
A) The image shows an impression by David A. Hardy (c PPARC) of the
possible scene from a moon orbiting the extra-solar planet in orbit
around the star HD70642. The planet has a mass about twice that of
Jupiter and orbits the star in around six years, with a nearly circular
orbit at more than three times the Earth-Sun distance. The star HD70642
is a 7th magnitude star in the southern constellation Puppis, and has
properties very similar to that of our Sun. The similarity of the
appearance of the extra- solar planet to that of Jupiter arises because
it has a similar mass. The possible existence of the moons been
inferred from our knowledge of the planets in our own Solar System and
from theories of planetary formation, they have not actually been
Photo credit: David A. Hardy, astroart.org
Copyright (c) Particle Physics and Astronomy Research Council
B. Animation of a trip from the Earth to the new HD 70642 planet.
Notes on the animation: 1) The artist's impression of the planet and
its hypothetical moons is a different one from the David Hardy image at
A; 2) the background Milky Way changes little during the trip because
the star is very close to the Earth, compared to the thousands of light
years to the center of our Galaxy; 3) The Southern Cross is shown at
the start because this southern star (we are observing from Australia)
is not far from the Southern Cross.
C. The 'orbit' diagram shows the size and shape of the star HD70642
orbit compared with the orbits of planets in our own Solar System.
D. Illustration of the Doppler Wobble Technique.
E. An image of the Anglo Australian Telescope at Siding Springs in
Australia can be found at
or a picture
of the dome at sunset
3.9-m Anglo-Australian telescope is the large telescope in the
For more information please contact:
Dr Hugh Jones
Liverpool John Moores University
Mobile: +44 (0) 7956 945276 (will be available during the conference on
Tel: +44 (0) 151 231 2909 (From Friday onwards)
Dr Alan Penny
Rutherford Appleton Laboratory
Tel: +44 (0) 1235 445675
Mobile: +44 (0) 7952-244-350
PPARC Press Office
Tel: +44 (0) 1793 442094
Dr Chris Tinney
Anglo Australian Observatory
Tel: +61 2 9372 4849
Mobile: +61 0416 092 117
Dr Brad Carter
University of Southern Queensland
Mobile +61 0401 337 319
Communications Manager, CSIRO
Tel: +61 2 9372 4251
Carnegie Institution of Washington
Dr R. Paul Butler and Dr C. McCarthy
Tel: +1 202 478 8866
Dr Geoff Marcy and Dr Debra Fischer
University of California, Berkeley
Tel: +1 510 642 1952 / 643 8973
Media Officer, National Science Foundation
Tel +1 703 292 7730
The Anglo-Australian Planet Search Home Page
Exoplanets Home Page
The Extra-solar Planets Encyclopaedia
The Particle Physics and Astronomy Research Council (PPARC) is the UK's
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