Last week, NASA released a newly restored image of a younger Earth. It was
taken from Lunar Orbiter 1 in 1966, the first of several orbiters that helped
gather data for the first moon landing in 1969. The photograph shows Earth just
cresting the Moon’s curving horizon, the first picture of our planet framed by
the surface of the Moon.
When the photograph was published, in 1966, it looked like a newsprint version
of a high-contrast snapshot from space, a stark scattering of whites and blacks.
The data from the lunar orbiter was stored on old analog tape drives. Now,
imaging experts at NASA have digitized those drives — mining data that could not
be recovered when they were first made — and produced a high-resolution version
of that historic photograph.
The rough surface of the moon no longer looks starkly black and white. It has
been rendered instead in a broad palette of grays, which give the moonscape a
dimensional presence it never had in the photograph that first appeared. The
cloud patterns that hide the surface of Earth, a crescent earth, are much more
subtle.
What is most evocative is the awareness that this is our planet in 1966, which
feels like a very long time ago. A train of thought immediately presents itself.
If scientists can recover extensive new information from old electronic data,
shouldn’t there be some way to peer beneath those clouds, back in time, and see
how this planet looked when it had only half its current population?
It is probably not possible to say that one Earth is ever more innocent than
another. And yet there is a feeling of innocence hanging over that beclouded
planet, which was just about to get the first glimpse of itself from the Moon.
If nature is left to its own devices, about 7.59 billion years from now Earth
will be dragged from its orbit by an engorged red Sun and spiral to a rapid
vaporous death. That is the forecast according to new calculations by a pair of
astronomers, Klaus-Peter Schroeder of the University of Guanajuato in Mexico and
Robert Connon Smith of the University of Sussex in England.
Their report, to be published in the Monthly Notices of the Royal Astronomical
Society, is the latest and gloomiest installment yet in a long-running debate
about the ultimate fate of our planet. Only last year, the discovery of a giant
planet orbiting the faint burned-out cinder of a star in Pegasus had suggested
that Earth could survive the Sun’s death.
Dr. Smith called the new result “a touch depressing” in a series of e-mail
messages. But “looked at another way,” he added, “it is an incentive to do
something about finding ways to leave our planet and colonize other areas in the
galaxy.”
As for sentimental attachment to any of the geographic features we might have
come to know and love, Dr. Smith said, “I should add that the Himalayas are a
passing thought anyway. They didn’t even exist until India smashed into Asia
less than 60 million years ago — the blink of an eye compared with the billions
of years we are discussing.”
While he does not expect the argument to end, Dr. Smith said in an e-mail
message that, if anything, in the new calculations he and Dr. Schroeder had
underestimated the forces that would be dragging the Earth down toward the Sun.
“So,” he said, “I would be surprised if anyone were able to rescue the Earth
again in a future paper.”
Roberto Silviotti of the Capodimonte Observatory in Naples, Italy, who found the
planet around that dead star in Pegasus, said it was not surprising that people
were interested in the fate of the earth, adding, “I think that the point is not
only that this is our planet but also that the we know the solar system and the
Sun much better than any other planetary system and therefore we should be able,
potentially, to make much better forecasts.”
Earth’s basic problem is that the Sun will gradually get larger and more
luminous as it goes through life, according to widely held theories of stellar
evolution. In its first 4.5 billion years, according to the models, the Sun has
already grown about 40 percent brighter.
Over the coming eons, life on Earth will become muggier and more uncomfortable
and finally impossible.
“Even if the Earth were to marginally escape being engulfed,” said Mario Livio,
an astronomer at the Space Telescope Science Institute, “it would still be
scorched, and life on Earth would be destroyed.”
About a billion years from now, the Sun will be 10 percent brighter. Oceans on
Earth will boil away. The Sun will run out of hydrogen fuel in its core about
5.5 billion years from now and start burning hydrogen in the surrounding layers.
As a result, the core will shrink and the outer layers will rapidly expand as
the Sun transforms itself into a red giant.
The heat from this death rattle will transform the solar system; it will briefly
be springtime in the Kuiper Belt out beyond Neptune. Mercury and Venus will
surely be swallowed, but the Earth’s fate has always been more uncertain.
The reason is that in the course of ballooning outward, the Sun will blow off a
substantial share of its mass. Thus, the Sun’s gravitational grip on its planets
will be weakened, and they will retreat to more distant orbits. The Earth will
wind up about where Mars is now, “on the border line between being engulfed or
escaping engulfment,” as Dr. Livio put it.
Whether or not the Earth is engulfed depends on which of two effects wins out.
At the same time that the Earth is retreating to a safer position, tidal forces
between it and the expanding Sun will try to drag the planet inward and
downward. In 2001, an analysis of these opposing forces by Kacper Rybicki of the
Polish Institute of Geophysics and Carlos Denis of the University of Liege
concluded that it looked bad but that the Earth might have a chance of
surviving.
According to Dr. Smith and Dr. Schroeder, that chance is nil. One key to their
work is a new way of calculating how much mass the Sun loses during its
cataclysmic expansion, and, thus, how big it gets and how far the Earth
eventually moves outward. The more mass lost, paradoxically, the bigger the Sun
swells, like a balloon whose elastic weakens when it is stretched. Using a new
technique, developed by Dr. Schroeder and Manfred Cuntz of the University of
Texas in Arlington, the authors calculated that the lost mass would amount to a
third of the Sun’s original mass, compared with previous estimates of a quarter.
As a result, the red giant version of the Sun — at its maximum — will be 256
times as big across as the star is today and 2,730 times as luminous.
Skimming over the flame tops of this giant, the bare, burned Earth would produce
a bulge in the Sun. But friction would cause the bulge to lag as it tried to
follow the Earth. The gravitational tug from the bulge would slow the Earth and
would cause it to spiral inward, where friction from gases in the Sun’s expanded
atmosphere would slow it even more.
Then it would go down.
After a period of burning helium and shrinking and expanding and then finally
shrinking again, the Sun will wind up as tiny cinder known as a white dwarf,
fading away for the rest of time.
Is there any way out of this fiery end for the robots or cockroaches or whoever
will be running the Earth in a billion years?
One option is to leave for another planet or another star system.
Another option, Dr. Smith said, is to engage in some large-scale high-stakes
engineering.
In the same way that space probes can get a trajectory boost by playing
gravitational billiards with Venus or Jupiter to gain speed and get farther out
in space, so the Earth could engineer regular encounters with a comet or
asteroid, thus raising its orbit and getting farther from the Sun, according to
a paper in 2001 by Don Korycansky and Gregory Laughlin of the University of
California, Santa Cruz, and Fred Adams of the University of Michigan.
Dr. Laughlin said that when their paper first came out, they were praised by the
radio host Rush Limbaugh and other conservatives for forward thinking.
But Dr. Laughlin said they were actually not advocating the orbit-shifting
project, noting that a miscalculation could lead to the comet’s hitting the
Earth.
“There are profound ethical issues involved,” he wrote in an e-mail message,
“and the cost of failure (an Earth-sterilizing impact) is unacceptably high.”
Anyway, such a maneuver would prolong the viability of the Earth for only a few
billion years. After that, the planet would be stranded in the cold and dim.
ORLANDO, Fla. (AP) -- Astrophysicist Stephen Hawking, who has been confined
to a wheelchair for most of his adult life, expects weightlessness to feel like
''bliss'' when he goes on a ''zero-gravity'' flight Thursday aboard a refitted
jet.
''For someone like me whose muscles don't work very well, it will be bliss to be
weightless,'' Hawking told The Associated Press in an interview Tuesday.
Hawking, 65, who has Lou Gehrig's disease, will be the first person with a
disability to fly on the one of the flights offered by Zero Gravity Corp., a
space tourism company.
Flying from Kennedy Space Center in Cape Canaveral, Fla., the jet creates the
experience of microgravity in 25-second bursts of steep plunges over the
Atlantic Ocean. Normally, the plane conducts 10 to 15 plunges for its passengers
who pay $3,750 for the ride, although that fee has been waived for Hawking.
On Hawking's trip, the jet will make a single plunge. Other plunges will be made
only after doctors and nurses who are accompanying the astrophysicist on the
ride have made sure that he is enjoying it.
''We consider ... having him weightless for 25 seconds is a successful
mission,'' said Peter Diamandis, the chairman and CEO of Zero Gravity. ''If we
do more than one, fantastic.''
Unable to use his hands, legs or voice, Hawking can only use his facial
expressions using the muscles around his eyes, eye brows and mouth to
communicate. Otherwise, he relies on a computer to talk for him in a synthesized
voice. The computer is attached to his wheelchair and allows him to choose words
on a computer screen via a sensor that detects motion in his cheek.
He won't have his wheelchair and talking computer on the jet with him, although
his assistant will bring a lap top in case he wants to communicate beyond facial
expressions.
''I hope it goes OK,'' Hawking said. ''But there's always a chance things can go
wrong.''
WASHINGTON (AP) -- For the first time astronomers have discovered a planet
outside our solar system that is potentially habitable, with Earth-like
temperatures, a find researchers described Tuesday as a big step in the search
for ''life in the universe.''
The planet is just the right size, might have water in liquid form, and in
galactic terms is relatively nearby at 120 trillion miles away. But the star it
closely orbits, known as a ''red dwarf,'' is much smaller, dimmer and cooler
than our sun.
There's still a lot that is unknown about the new planet, which could be deemed
inhospitable to life once more is known about it. And it's worth noting that
scientists' requirements for habitability count Mars in that category: a size
relatively similar to Earth's with temperatures that would permit liquid water.
However, this is the first outside our solar system that meets those standards.
''It's a significant step on the way to finding possible life in the universe,''
said University of Geneva astronomer Michel Mayor, one of 11 European scientists
on the team that found the planet. ''It's a nice discovery. We still have a lot
of questions.''
The results of the discovery have not been published but have been submitted to
the journal Astronomy and Astrophysics.
Alan Boss, who works at the Carnegie Institution of Washington where a U.S. team
of astronomers competed in the hunt for an Earth-like planet, called it ''a
major milestone in this business.''
The planet was discovered by the European Southern Observatory's telescope in La
Silla, Chile, which has a special instrument that splits light to find wobbles
in different wave lengths. Those wobbles can reveal the existence of other
worlds.
What they revealed is a planet circling the red dwarf star, Gliese 581. Red
dwarfs are low-energy, tiny stars that give off dim red light and last longer
than stars like our sun. Until a few years ago, astronomers didn't consider
these stars as possible hosts of planets that might sustain life.
The discovery of the new planet, named 581 c, is sure to fuel studies of planets
circling similar dim stars. About 80 percent of the stars near Earth are red
dwarfs.
The new planet is about five times heavier than Earth. Its discoverers aren't
certain if it is rocky like Earth or if its a frozen ice ball with liquid water
on the surface. If it is rocky like Earth, which is what the prevailing theory
proposes, it has a diameter about 1 1/2 times bigger than our planet. If it is
an iceball, as Mayor suggests, it would be even bigger.
Based on theory, 581 c should have an atmosphere, but what's in that atmosphere
is still a mystery and if it's too thick that could make the planet's surface
temperature too hot, Mayor said.
However, the research team believes the average temperature to be somewhere
between 32 and 104 degrees and that set off celebrations among astronomers.
Until now, all 220 planets astronomers have found outside our solar system have
had the ''Goldilocks problem.'' They've been too hot, too cold or just plain too
big and gaseous, like uninhabitable Jupiter.
The new planet seems just right -- or at least that's what scientists think.
''This could be very important,'' said NASA astrobiology expert Chris McKay, who
was not part of the discovery team. ''It doesn't mean there is life, but it
means it's an Earth-like planet in terms of potential habitability.''
Eventually astronomers will rack up discoveries of dozens, maybe even hundreds
of planets considered habitable, the astronomers said. But this one -- simply
called ''c'' by its discoverers when they talk among themselves -- will go down
in cosmic history as No. 1.
Besides having the right temperature, the new planet is probably full of liquid
water, hypothesizes Stephane Udry, the discovery team's lead author and another
Geneva astronomer. But that is based on theory about how planets form, not on
any evidence, he said.
''Liquid water is critical to life as we know it,'' co-author Xavier Delfosse of
Grenoble University in France, said in a statement. ''Because of its temperature
and relative proximity, this planet will most probably be a very important
target of the future space missions dedicated to the search for extraterrestrial
life. On the treasure map of the Universe, one would be tempted to mark this
planet with an X.''
Other astronomers cautioned it's too early to tell whether there is water.
''You need more work to say it's got water or it doesn't have water,'' said
retired NASA astronomer Steve Maran, press officer for the American Astronomical
Society. ''You wouldn't send a crew there assuming that when you get there,
they'll have enough water to get back.''
The new planet's star system is a mere 20.5 light years away, making Gliese 581
one of the 100 closest stars to Earth. It's so dim, you can't see it without a
telescope, but it's somewhere in the constellation Libra, which is low in the
southeastern sky during the midevening in the Northern Hemisphere.
''I expect there will be planets like Earth, but whether they have life is
another question,'' said renowned astrophysicist Stephen Hawking in an interview
with The Associated Press in Orlando. ''We haven't been visited by little green
men yet.''
Before you book your extrastellar flight to 581 c, a few caveats about how alien
that world probably is: Anyone sitting on the planet would get heavier quickly,
and birthdays would add up fast since it orbits its star every 13 days.
Gravity is 1.6 times as strong as Earth's so a 150-pound person would feel like
240 pounds.
But oh, the view. The planet is 14 times closer to the star it orbits. Udry
figures the red dwarf star would hang in the sky at a size 20 times larger than
our moon. And it's likely, but still not known, that the planet doesn't rotate,
so one side would always be sunlit and the other dark.
Distance is another problem. ''We don't know how to get to those places in a
human lifetime,'' Maran said.
Two teams of astronomers, one in Europe and one in the United States, have been
racing to be the first to find a planet like 581 c outside the solar system.
The European team looked at 100 different stars using a tool called HARPS (High
Accuracy Radial Velocity for Planetary Searcher) to find this one planet, said
Xavier Bonfils of the Lisbon Observatory, one of the co-discoverers.
Much of the effort to find Earth-like planets has focused on stars like our sun
with the challenge being to find a planet the right distance from the star it
orbits. About 90 percent of the time, the European telescope focused its search
more on sun-like stars, Udry said.
A few weeks before the European discovery earlier this month, a scientific paper
in the journal Astrobiology theorized a few days that red dwarf stars were good
candidates.
''Now we have the possibility to find many more,'' Bonfils said.
When astronauts return from space, what they talk about isn't the brute force
of the rocket launch or the exhilaration of zero gravity -- it's the view. And
it's mankind's rarest view of all, Earth from afar.
Only two dozen men -- those who journeyed to the moon -- have seen the full
Earth view. Most space travelers, in low orbit, see only a piece of the planet
-- a lesser but still impressive glimpse. They have seen the curvature of Earth,
its magnificent beauty, its fragility, and its lack of borders.
The first full view of Earth came from the moon-bound Apollo 8 during the waning
days of a chaotic 1968. Apollo 8 astronaut Bill Anders put it in perspective in
a documentary: ''We came all this way to explore the moon, and the most
important thing is that we discovered the Earth.''
Some of the photos Anders took were used on posters and pins on the first Earth
Day in 1970. They've been ''an environmental staple of Earth Days ever since,''
said Denis Hayes, the first Earth Day coordinator.
For Earth Day this year -- at a time when perhaps some perspective is needed --
The Associated Press asked space travelers to recall what it's like to see Earth
from above:
''It was the only color we could see in the universe. ... ''We're living on a
tiny little dust mote in left field on a rather insignificant galaxy. And
basically this is it for humans. It strikes me that it's a shame that we're
squabbling over oil and borders.''
--Bill Anders, Apollo 8, whose photos of Earth became famous.
''It's hard to appreciate the Earth when you're down right upon it because it's
so huge.
''It gives you in an instant, just at a position 240,000 miles away from it, (an
idea of) how insignificant we are, how fragile we are, and how fortunate we are
to have a body that will allow us to enjoy the sky and the trees and the water
... It's something that many people take for granted when they're born and they
grow up within the environment. But they don't realize what they have. And I
didn't till I left it.''
--Jim Lovell, Apollo 8 and 13.
''The sheer beauty of it just brought tears to my eyes.
''If people can see Earth from up here, see it without those borders, see it
without any differences in race or religion, they would have a completely
different perspective. Because when you see it from that angle, you cannot think
of your home or your country. All you can see is one Earth....''
--Anousheh Ansari, Iranian-American space tourist who flew last year to the
international space station.
''Up in space when you see a sunset or sunrise, the light is coming to you from
the sun through that little shell of the Earth's atmosphere and back out to the
spacecraft you're in. The atmosphere acts like a prism. So for a short period of
time you see not only the reds, oranges and yellows, the luminous quality like
you see on Earth, but you see the whole spectrum
red-orange-yellow-blue-green-indigo-violet.
''You come back impressed, once you've been up there, with how thin our little
atmosphere is that supports all life here on Earth. So if we foul it up, there's
no coming back from something like that.''
--John Glenn, first American to orbit the Earth (1962) and former U.S. senator.
''I think you can't go to space and not be changed, in many ways ....
''All of the teachings of the Bible that talk about the creator and his creation
take on new meaning when you can view the details of the Earth from that
perspective. So it didn't change my faith per se, the content of it, but it just
enhanced it, it made it even more real.''
--Jeff Williams, spent 6 months on the space station and set a record for most
Earth photos taken.
''Earth has gone through great transitions and volcanic impacts and all sorts of
traumatic things. But it has survived ... I'm not referring to human conflicts.
I'm referring to the physical appearance of the Earth at a great distance. That
it generally is mostly very peaceful (when) looked at from a distance.''
--Buzz Aldrin, second man to walk on the moon.
''I see the deep black of space and this just brilliantly gorgeous blue and
white arc of the earth and totally unconsciously, not at all able to help
myself, I said, 'Wow, look at that.'''
--Kathy Sullivan, first American woman to spacewalk, recalling what she said
when she saw Earth in 1984.
''...From up there, it looks finite and it looks fragile and it really looks
like just a tiny little place on which we live in a vast expanse of space. It
gave me the feeling of really wanting us all to take care of the Earth. I got
more of a sense of Earth as home, a place where we live. And of course you want
to take care of your home. You want it clean. You want it safe.''
--Winston Scott, two-time shuttle astronaut who wrote a book, ''Reflections From
Earth Orbit.''
''You change because you see your life differently than when you live on the
surface everyday. ... We are so involved in our own little lives and our own
little concerns and problems. I don't think the average person realizes the
global environment that we really live in. I certainly am more aware of how
fragile our Earth is, and, frankly, I think that I care more about our Earth
because of the experiences I've had traveling in space.''
--Eileen Collins, first female space shuttle commander.
''You can see what a small little atmosphere is protecting us.
''You realize there's not much protecting this planet particularly when you see
the view from the side. That's something I'd like to share with everybody so
people would realize we need to protect it.''
--Sunita Williams, who has been living on the international space station since
Dec. 11, 2006.
''I left Earth three times. I found no place else to go. Please take care of
Spaceship Earth.''
--Wally Schirra, who flew around Earth on Mercury, Gemini and Apollo missions in
the 1960s.
