SCIENCE & TECHNOLOGY

Forty years since the first picture of earth from space
Steve Connor

They went to the moon, but ended up discovering the earth. The crew of Apollo 8 were the first people to leave earth’s orbit and pass behind the far side of the moon. They had been drilled and trained for just about every eventuality, save one — the awe-inspiring sight of seeing our own planet hanging over an empty lunar horizon.

Antarctica too is warming
Antarctica, the only place that had oddly seemed immune from climate change, is warming after all, according to a new study. For years, Antarctica was an enigma to scientists who track the effects of global warming. Temperatures on much of the continent at the bottom of the world were staying the same or slightly cooling, previous research indicated.


Prof Yash Pal
Prof Yash Pal

THIS UNIVERSE
PROF YASH PAL

Generally, due to centrifugal force the matter moves away from the centre of a revolving body. But when dissolving sugar in water we revolve the water in vessel and then after it stops the sugar particles settle at the centre of the vessel. Why?

 


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Forty years since the first picture of earth from space
Steve Connor

They went to the moon, but ended up discovering the earth. The crew of Apollo 8 were the first people to leave earth’s orbit and pass behind the far side of the moon. They had been drilled and trained for just about every eventuality, save one — the awe-inspiring sight of seeing our own planet hanging over an empty lunar horizon.

It later became known as “Earthrise” and the image of the world rising in the dark vastness of space over a sun-lit lunar landscape became an iconic reminder of our lonely planet’s splendid isolation and delicate fragility.

The image was captured during Christmas Eve 1968 but the photographs themselves appeared for the first time in print 40 years ago this month. It was an image that would eventually launch a thousand environmental movements, such was its impact on the public consciousness.

The three-man crew of Apollo 8 — Frank Borman, Jim Lovell and Bill Anders — were carrying out the necessary groundwork for the later manned landing on the moon and were the first people to orbit the moon, flying around the far side which is not visible from earth.

They were also in effect the first people to lose complete contact with their own planet, not being able to see or radio Earth for the duration of their journey behind the moon. It was only when they completed the orbit that they could regain contact.

Ironically, for the first three orbits, the crew had their backs to the earth as it re-appeared over the lunar horizon and did not see the iconic view that would change their lives. It was only on the fourth orbit that one of the men turned round and saw the spectacle for the first time.

“Oh my God! Look at that picture over there! Isn’t that something?” he said, his words captured for posterity on the on-board tape recorder. They quickly scrambled for a camera — the first couple of images of “Earthrise” were in black and white, subsequent photos were taken in colour. It is these colour photographs that became the iconic images of the environmental movement.

They showed the stark contrast between the grey, desolate landscape of the lifeless moon and the vivid blue-and-white orb of the fertile earth — a symbol of warmth and life in a bleak desert of deathly coldness.

Sir Fred Hoyle, the great British cosmologist, rightly predicted in 1948 that the first images of earth from space would change forever our view of our own planet. “Earthrise” encapsulated the fragility of a place that seems so immense to the people who live there, but so tiny when viewed from the relatively short distance of its natural satellite.

Since then, hundreds of still images were taken of earth during the nine Apollo flights to the moon, but only 24 people have seen the whole of the earth from space.

The American astronomer Carl Sagan captured the mood well when another picture of earth was taken from space, this time in 1990 by the Voyager 1 spacecraft at a distance of 3.7 billion miles.

In this picture, the earth appeared as a “pale blue dot” surrounded by the vastness of space, like a tiny mote of dust caught in a sunbeam.

“Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives,” Sagan said in 1996.

“Our posturing, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.”

And so it took catching sight of our own place in space to realise that the earth is the only home we have, and we had better look after it.

By arrangement with The Independent, London

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Antarctica too is warming

Antarctica, the only place that had oddly seemed immune from climate change, is warming after all, according to a new study. For years, Antarctica was an enigma to scientists who track the effects of global warming. Temperatures on much of the continent at the bottom of the world were staying the same or slightly cooling, previous research indicated.

The new study went back further than earlier work and filled in a massive gap in data with satellite information to find that Antarctica too is getting warmer, like the Earth’s other six continents.

The findings were published in Thursday’s issue of the journal Nature.

“Contrarians have sometime grabbed on to this idea that the entire continent of Antarctica is cooling, so how could we be talking about global warming,” said study co-author Michael Mann, director of the Earth System Science Center at Penn State University. “Now we can say: no, it’s not true ... It is not bucking the trend.”

The study does not point to man-made climate change as the cause of the Antarctic warming - doing so is a highly intricate scientific process - but a different and smaller study out late last year did make that connection.

“We can't pin it down, but it certainly is consistent with the influence of greenhouse gases,” said NASA scientist Drew Shindell, another study co-author.

Some of the effects also could be natural variability, he said.

The study showed that Antarctica - about one-and-a-half times bigger than the United States - remains a complicated weather picture, especially with only a handful of monitoring stations in its vast interior.

The researchers used satellite data and mathematical formulas to fill in missing information.

That made outside scientists queasy about making large conclusions with such sparse information.

“This looks like a pretty good analysis, but I have to say I remain somewhat skeptical,” Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, said in an e-mail. “It is hard to make data where none exist.”

Shindell said it was more comprehensive than past studies and jibed with computer models. — AP

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THIS UNIVERSE
PROF YASH PAL

Generally, due to centrifugal force the matter moves away from the centre of a revolving body. But when dissolving sugar in water we revolve the water in vessel and then after it stops the sugar particles settle at the centre of the vessel. Why?

As soon as I read your question, it came to my mind that Einstein  had  addressed a similar common observation  that if you stir around a cup of tea with tea leaves  and then stop rotating the spoon,  the leaves settle down in the middle of the cup.

This paper, I think, was written in 1934!  I have not been able to lay my hands on that paper but have done a little thinking about this intriguing observation. I will share it with you with a warning that I may not be entirely correct. Here goes: When you spin the tea around, the centrifugal force raises the level of the liquid towards the wall of the cup. (Indeed it can be shown that the surface  of the liquid  would become concave  acquiring a parabolic shape). 

When you stop stirring, the liquid close to the walls of the cup starts descending from all sides and forms a sort of whirlwind around the centre of the cup.

A vortex is formed and the velocity of rotation at the centre of this vortex is minimum resulting in a calm area where the settled grains of sugar or tiny soaked tea leaves are not disturbed. Away from the centre such a calm area is not established for quite a while. This might be the reason for the observation you have made. I hope I have not goofed in giving you this explanation.

As per my information gathered from planetariums and encyclopaedias, all the material in space is either in solid or gaseous state. Why not liquid? Please clarify.

It is true that the range of temperature within which matter can be in liquid state is rather small at ordinary pressures. But think of the surface of the earth. This is also part of space. Water covers most of it. Even inside the earth, where the temperature and pressure are both very high, we have melted rocks and metal. This would also be true in other large planets.

Readers wanting to ask Prof Yash Pal a question can e-mail him at @@palyash.pal@gmail.com

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