Scientific reasons behind the seasons of EARTH

Scientific reasons behind the seasons of  EARTH

The seasons are a powerful force in our lives. They affect the activities we do, the foods we crave, the clothes we wear — and quite often, the moods we are in. The seasons officially change once again on Saturday, with summer beginning in the Northern Hemisphere and winter starting in the south.
What is it that causes the change in seasons?
The ability to predict the seasons — by tracking the rising and setting points of the sun throughout the year — was key to survival in ancient times. The Babylonians, the Maya and other cultures developed complex systems for monitoring seasonal shifts. But it took centuries more to unravel the science behind the seasons.
Nicolai Copernicus (1473-1543) radically changed our understanding of astronomy when he proposed that the sun, not Earth, was the center of the solar system. This led to our modern understanding of the relationship between the sun and Earth.

Missing Air asia flight updates- black box recovered

Missing Air asia flight updates- black box recovered

fresh update !

Is a walking, talking plant-person possible? by Groot

Lumbering around on his barky limbs, sprouting flowers and even dancing in a pot, one of the stars of the film "Guardians of the Galaxy" bizarrely blends the plant and animal kingdoms. "Groot," awalking, talking tree, seems to defy nature but how outlandish is the idea of a plant-animal hybrid?
                           

. Some scientists even say Earth's biology suggests the possibility of "thinking plants" somewhere in the universe.Plants that can smell and animals that regenerate show that animal and vegetable kingdoms may not be as far apart as they first appear.

Here, experts tell how Groot-like blending could occur, and some reasons it couldn't. [Science Fact or Fiction? The Plausibility of 10 Scintific-Fiction Concepts]

Plant sight, plant hearing


                               

In the film, Groot clearly hears, sees, feels and talks (albeit, only three words, "I am Groot"). While one would be hard-pressed to find a talking vegetable on Earth, the idea of communicating and sensing plants is not at all outlandish, 

In fact, plants have a much richer, more dynamic life than most people give the leafy beings credit for, Chamovitz said. "We think of plants as un-living, because they're unmoving," Chamovitz said. "The strong scientific evidence is that plants can do everything other than hearing."

They respond to chemicals, with lock-and-key mechanisms that resemble how animals smell. Plants have specific photoreceptors, which are proteins that respond to different wavelengths of light. They "know" when they're being touched, Simon Gilroy, a professor of botany at the University of Wisconsin-Madison, told Live Science.

Plants also have proprioception, or a sense of their location in space, Chamovitz said, which is why they can tell when they're planted upside-down.

Some plants can even "hear," able to distinguish the vibration patterns made by different chewing caterpillars, according to a study detailed this summer in the journal Oecologia, Gilroy said. (Decades-old claims that plants can "hear music," however, have little to no scientific support, he added.)

This plant sensing may not seem evident after all, plants don't scream in pain or comment on Van Gogh's use of color. But senses serve the same function in plants as they do in animals: Plants take in information, which travels through the plant body and causes some sort of response, Chamovitz said. [In Photos: Animals That Mimic Plants]

The familiar scene of houseplants growing toward the window, for example, shows how plants sense and respond to light. When part of a plant gets eaten, that causes distress chemicals to propagate through the plant, which responds with chemical changes to make itself less tasty to the predator, Gilroy said.

Not only can plants send signals within their own "bodies," but those signals can also influence other plants. In other words, they communicate, Chamovitz said. A disease or pest infestation in a neighboring plant sends out chemical signals that cause nearby plants to respond. "They can smell when neighbors are sick," Chamovitz said. "It gives off a chemical, so the plant defends itself."

Researchers have also shown corn seedlings lean toward sounds with a 220-Hertz frequency, the same tune emitted by the plants' roots, and chili seedlings grow quicker when they sense a fennel plant is growing nearby.

Moving but a bit  slowly
                                  

Groot does more than just sense and communicate, though. He also moves around. This woody best friend to a talking raccoon shifts around on mobile stumps and lifts alien bullies up by their nostrils.

"Thinking about it, the feature that really isn't plantlike about Groot is the speed of the movement," Gilroy said.

Plants, for the most part, simply can't move that fast. Animals have "squishy cells" that can move past one another, making muscles feasible, Gilroy said. But a hard wall encloses each plant cell, and neighboring cells are glued together into a rigid grid.

"Things like muscles are impossible with how plants are set up," he said.

Moreover, a plant's entire body-plan centers upon staying put, so they can maximize photosynthesis with networks of branches and roots. Chamovitz calls "rootedness" the primary principle of plant biology.

Plants do make movements, however they just do it by growing, Gilroy said. For example, they "move" toward the sunlight by elongating cells on the dark side of the stem. "Plants grow through the environment," Gilroy said.

Due to some clever mechanisms, a few notable species buck the rule of the slow-moving plant. The famous Venus flytrap shuts its jaws rapidly by essentially "growing them shut," Gilroy said. Acid released at the flytrap's hinge softens cell walls and makes them expand quickly. [Image Gallery: Carnivorous Plants]

Finally, plants have to stay put because movement burns so much energy

photosynthesis simply can't power animal-style activity, which is why animals eat plants and other animals. To move around like Groot does on screen, such a tree creature would have to eat other things, too, Gilroy said.

Stem cells and Groot

                             

Despite his (relatively) quick movements, Groot still maintains some plantlike characteristics. Capable of unlimited growth and regeneration, he grabs an out-of-reach battery by simply growing taller. His lopped-off arms return, and there's even a bit in the movie about replanting a Groot "cutting."

Clearly, the movie speeds up such vegetable growth, but real-life plants can indeed keep growing in ways animals can't, Ed Rayburn, an extension specialist and forage agronomist for West Virginia University, told Live Science. Those plant species capable of "unlimited growth" can keep going and going "for what, to humans, seems like forever," he said. And plants commonly regenerate lost limbs.

Those abilities derive from the way plants are structured and their access to stem cells.

Arranged in modular body plans, plants can grow limbs in different directions and add secondary limbs in a fractal pattern. Animals, by contrast, grow to a predetermined size and shape, and much of that happens in the womb, Gilroy said.

"We cram all our development into as short a time as possible," Gilroy said. But since plants can't run, and so will inevitably suffer damage, they have to keep growing throughout life, he said.

Plant stem cells are found in meristems, "small groups of cells that stay perpetually embryonic," Gilroy said. Located at stem and root tips, these plant stem cells are pluripotent, meaning they can develop into any type of plant cell. After injury, any plant cell can revert to similar pluripotency.

Animals, by contrast, lack meristems, and stem cells are much harder to come by, as shown by the difficulties faced by cloning efforts, Rayburn said. Some animals do approach plantlike regenerative growth, but usually those with simple body plans, like the planarian worm, Gilroy said.

plants that are called Intelligent plants?

Plant communication even has some researchers in the new field of plant neurobiology considering the potential for leafy intelligence. Alien worlds, some scientists say, could theoretically birth sentient plants.

But, Chamovitz said, such green thinkers would have to change the core trait of plants their rootedness. Animals developed thought because of their "searching" strategy for finding food, he told Forbes. Alien tree-thinkers would have to incorporate movement, perhaps with "some type of root system that can push itself out of the ground, take three steps forward and then re-root," he told Forbes.

As for creating plant-animal hybrids here on Earth, that's most likely to happen in a geneticist's lab. It's theoretically possible, given the right gene transfers, to give people a coating of green, photosynthetic skin. To actually make much use of such a feature, however, people would have to grow a canopy of leaves.

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Have we already found Earth 2.0?

Have we already found Earth 2.0? 

Within 20 years, NASA expects to confirm ‘we are not alone’ and find the first traces of alien life

Exoplanets: Searching for Earth 2.0 6:44

Astronomer Dr Alan Duffy is on the search for exoplanets in our distant universe and explains how we'll find extraterrestrial life.


100 MILLION worlds may hold alien life in our galaxy. Now NASA has detailed exactly how it expects to find the first inhabited planet other than our own within our lifetimes.
“Just imagine the moment, when we find potential signatures of life. Imagine the moment when the world wakes up and the human race realises that its long loneliness in time and space may be over — the possibility we’re no longer alone in the universe,” Matt Mountain, director and Webb telescope scientist at the Space Telescope Science Institute in Baltimore said this morning.
That moment, he believes, is likely to be within the next 20 years.

Exoplanets
A meeting was held at NASA’s Washington headquarters this morning to detail international efforts aimed at finding life out there.
The presentation detailed NASA’s road map for the search for life in the universe, involving a series of current and future telescopes.
“Sometime in the near future, people will be able to point to a star and say, ‘that star has a planet like Earth’,” Sara Seager, professor of planetary science and physics at the Massachusetts Institute of Technology in Cambridge, Massachusetts, told the gathering of NASA and affiliated planet hunters.

Planet hunters ... John Grunsfeld, John Mather, Sara Seager, Dave Gallagher and Matt Moun
Planet hunters ... John Grunsfeld, John Mather, Sara Seager, Dave Gallagher and Matt Mountain discuss "the scientific and technological road map that will lead to the discovery of potentially habitable worlds among the stars". Source: AFP
The meeting comes after a group of international astronomers and astrobiologists published new research assessing the possibility of complex life on other worlds.
Their estimate — described as conservative — calculates 100 million worlds in our own galaxy are able to sustain complex alien life. That’s from among the 17 billion Earth-sized worlds believed to be spinning around the Milky Way’s 100 billion stars.
“I think in the next 20 years we will find out if we are not alone in the universe,” NASA Astronomer Kevin Hand said yesterday.
The planet hunt has been picking up pace in recent years. What started as ground-based radio observatories and telescopes has already moved to space-based facilities such as the Hubble, Kepler and Spitzer telescopes.
What they can tell is limited, but revealing: They can determine if a planet is the right distance from a start to hold liquid water.
This is the “Goldilocks Zone”, where conditions are “not to cold, not too hot — just right” for life as we
know it.

Not too hot, not too cold — just right ... This NASA artist's conception llustrates Keple
Not too hot, not too cold — just right ... This NASA artist's conception illustrates Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star. Source: AFP
So far, the few “best contenders” for life are believed to have conditions little better than that found on Jupiter’s moon, Europa
But NASA has now detailed a new generation of telescopes being built on the ground and being sent into orbit in the search for “Earth 2.0”.
Much of its hopes for finding evidence of life is being placed in the Transiting Exoplanet Surveying Satellite (TESS), due to be launched in 2017, the James Webb Space Telescope in 2018 and two further as-yet-unfunded projects scheduled for the next decade.
New space telescope to answer the big question, Are we alone?” 1:50



The James Webb space telescope is being sent almost a million miles away, tasked with answering the question: 'Are we alone?'
These telescopes will not only find and position a planet, they are hoped to provide clues as to their atmospheric make-up and greatly refine what we have already inferred.
In particular, they’ll be looking for water. But they’ll also be looking for other signs.
“Chemicals in our atmosphere like methane and oxygen would quickly combine meaning
something has to be replenishing them, so if we find these in another world’s atmosphere
we have a clue that something is creating it,” Australian astronomer Dr Alan Duffy, Research Fellow at the Swinburne University of Technology, said this morning. “This might not be life but it’s a first clue.”
Eye on space ... An artist's concept depicts NASA's Kepler mission's smallest habitable z
Eye on space ... An artist's concept depicts NASA's Kepler mission's smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1200 light-years from Earth in the constellation Lyra. Source: AFP
The success of the planet-hunting program has produced phenomenal results in recent years.
Since its launch in 2009, the Kepler telescope shook up the astronomy community with its discovery of more than 5000 potential exoplanets, of which more than 1700 have been confirmed.
“This technology we are using to explore exoplanets is real,” said John Grunsfeld, astronaut and associate administrator for NASA’s Science Mission Directorate in Washington. “The James Webb Space Telescope and the next advances are happening now. These are not dreams — this is what we do at NASA.”
This decade has seen the discovery of more and more super Earths, which are rocky planets that are larger and heftier than Earth. Finding smaller planets, the Earth twins, is a tougher challenge
Kepler was the first to pinpoint planets known to be within the “Goldilocks Zone”, and indicates most worlds at that range are generally less than three-times the size of Earth.
“What we didn’t know five years ago is that perhaps 10 to 20 per cent of stars around us have Earth-size planets in the habitable zone,” says Matt Mountain, director and Webb telescope scientist at the Space Telescope Science Institute in Baltimore. “It’s within our grasp to pull off a discovery that will change the world forever.”