Andrew Yee[_1_]
February 26th 08, 04:17 PM
Press and Communications Office
University of Sussex
For more information, contact:
Jacqui Bealing or Maggie Clune
University of Sussex Press Office
01273 678888
21 February 2008
The Sun will vaporise the Earth unless we can change our orbit
New calculations by University of Sussex astronomers predict that the Earth
will be swallowed up by the Sun in about 7.6 billion years unless the
Earth's orbit can be altered.
Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously
calculated that the Earth would escape ultimate destruction, although be
battered and burnt to a cinder. But this did not take into account the
effect of the drag caused by the outer atmosphere of the dying Sun.
He says: "We showed previously that, as the Sun expanded, it would lose mass
in the form of a strong wind, much more powerful than the current solar
wind. This would reduce the gravitational pull of the Sun on the Earth,
allowing the Earth's orbit to move outwards, ahead of the expanding Sun.
"If that were the only effect the Earth would indeed escape final
destruction. However, the tenuous outer atmosphere of the Sun extends a long
way beyond its visible surface, and it turns out the Earth would actually be
orbiting within these very low density outer layers. The drag caused by this
low-density gas is enough to cause the Earth to drift inwards, and finally
to be captured and vaporised by the Sun."
The new paper was written in collaboration with Dr Klaus-Peter Schroeder,
previously at Sussex, who is now in the Astronomy Department of the
University of Guanajuato in Mexico.
Life on Earth will have disappeared long before 7.6 billion years, however.
Scientists have shown that the Sun's slow expansion will cause the
temperature at the surface of the Earth to rise. Oceans will evaporate, and
the atmosphere will become laden with water vapour, which (like carbon
dioxide) is a very effective greenhouse gas. Eventually, the oceans will
boil dry and the water vapour will escape into space. In a billion years
from now the Earth will be a very hot, dry and uninhabitable ball.
Can anything be done to prevent this fate? Professor Smith points to a
remarkable scheme proposed by a team at Santa Cruz University, who suggest
harnessing the gravitational effects of a close passage by a large asteroid
to "nudge" the Earth's orbit gradually outwards away from the encroaching
Sun. A suitable passage every 6000 years or so would be enough to keep the
Earth out of trouble and allow life to survive for at least 5 billion years,
and possibly even to survive the Sun's red giant phase.
"This sounds like science fiction," says Professor Smith. "But it seems that
the energy requirements are just about possible and the technology could be
developed over the next few centuries." However, it is a high-risk strategy
-- a slight miscalculation, and the asteroid could actually hit the Earth,
with catastrophic consequences. "A safer solution may be to build a fleet of
interplanetary 'life rafts' that could manoeuvre themselves always out of
reach of the Sun, but close enough to use its energy," he adds.
Notes for editors
* 'Distant Future of the Sun and Earth Revisted', by Dr Klaus-Peter
Schroeder and Professor Robert Smith, Astrophysics
http://uk.arxiv.org/abs/0801.4031
* Earlier press release, 2002
http://www.sussex.ac.uk/press_office/media/media191.shtml
* 'Astronomical engineering: a strategy for modifying planetary orbits'. D G
Korycansky of the University of California at Santa Cruz, with colleagues
Greg Laughlin and Fred Adams: (Astrophysics & Space Science, 275, 349-366,
2001)
University of Sussex
For more information, contact:
Jacqui Bealing or Maggie Clune
University of Sussex Press Office
01273 678888
21 February 2008
The Sun will vaporise the Earth unless we can change our orbit
New calculations by University of Sussex astronomers predict that the Earth
will be swallowed up by the Sun in about 7.6 billion years unless the
Earth's orbit can be altered.
Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously
calculated that the Earth would escape ultimate destruction, although be
battered and burnt to a cinder. But this did not take into account the
effect of the drag caused by the outer atmosphere of the dying Sun.
He says: "We showed previously that, as the Sun expanded, it would lose mass
in the form of a strong wind, much more powerful than the current solar
wind. This would reduce the gravitational pull of the Sun on the Earth,
allowing the Earth's orbit to move outwards, ahead of the expanding Sun.
"If that were the only effect the Earth would indeed escape final
destruction. However, the tenuous outer atmosphere of the Sun extends a long
way beyond its visible surface, and it turns out the Earth would actually be
orbiting within these very low density outer layers. The drag caused by this
low-density gas is enough to cause the Earth to drift inwards, and finally
to be captured and vaporised by the Sun."
The new paper was written in collaboration with Dr Klaus-Peter Schroeder,
previously at Sussex, who is now in the Astronomy Department of the
University of Guanajuato in Mexico.
Life on Earth will have disappeared long before 7.6 billion years, however.
Scientists have shown that the Sun's slow expansion will cause the
temperature at the surface of the Earth to rise. Oceans will evaporate, and
the atmosphere will become laden with water vapour, which (like carbon
dioxide) is a very effective greenhouse gas. Eventually, the oceans will
boil dry and the water vapour will escape into space. In a billion years
from now the Earth will be a very hot, dry and uninhabitable ball.
Can anything be done to prevent this fate? Professor Smith points to a
remarkable scheme proposed by a team at Santa Cruz University, who suggest
harnessing the gravitational effects of a close passage by a large asteroid
to "nudge" the Earth's orbit gradually outwards away from the encroaching
Sun. A suitable passage every 6000 years or so would be enough to keep the
Earth out of trouble and allow life to survive for at least 5 billion years,
and possibly even to survive the Sun's red giant phase.
"This sounds like science fiction," says Professor Smith. "But it seems that
the energy requirements are just about possible and the technology could be
developed over the next few centuries." However, it is a high-risk strategy
-- a slight miscalculation, and the asteroid could actually hit the Earth,
with catastrophic consequences. "A safer solution may be to build a fleet of
interplanetary 'life rafts' that could manoeuvre themselves always out of
reach of the Sun, but close enough to use its energy," he adds.
Notes for editors
* 'Distant Future of the Sun and Earth Revisted', by Dr Klaus-Peter
Schroeder and Professor Robert Smith, Astrophysics
http://uk.arxiv.org/abs/0801.4031
* Earlier press release, 2002
http://www.sussex.ac.uk/press_office/media/media191.shtml
* 'Astronomical engineering: a strategy for modifying planetary orbits'. D G
Korycansky of the University of California at Santa Cruz, with colleagues
Greg Laughlin and Fred Adams: (Astrophysics & Space Science, 275, 349-366,
2001)