Life Beyond Earth
Origin and Evolution of Life in the Universe
|Life Beyond Earth
Origin And Evolution Of Life In The Universe
Carl Edward Sagan (November 9th, 1934 – December 20th, 1996) was an American astronomer, astrophysicist, author, cosmologist, and highly successful popularizer of astronomy, astrophysics and other natural sciences. During his lifetime, he published more than 600 scientific papers and popular articles and was author, co-author, or editor of more than 20 books.
In his works, he advocated skeptical inquiry and the scientific method. He pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI).
Sagan became world-famous for his popular science books and for the award-winning 1980 television series Cosmos: A Personal Voyage, which he narrated and co-wrote.
A book to accompany the program was also published. Sagan also wrote the novel Contact, the basis for the 1997 film of the same name.
Outer space, also simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace (and terrestrial locations).
There is no discrete boundary between the Earth's atmosphere and space, as the atmosphere gradually attenuates with increasing altitude. Outer space within the solar system is called interplanetary space, which passes over into interstellar space at what is known as the heliopause.
Ahead of TVO's exclusive broadcast of renowned physicist Stephen Hawking
at the Perimeter Institute in Waterloo, Ontario on Sunday, June 20th,
we examine Stephen Hawking's contribution to our understanding of the
Outer space is certainly spacious, but it is far from empty.
Outer space is sparsely filled with several dozen types of organic molecules discovered to date by microwave spectroscopy, blackbody radiation left over from the big bang and the origin of the universe, and cosmic rays, which include ionized atomic nuclei and various subatomic particles.
There is also some gas, plasma and dust, and small meteors.
Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this debris re-enters the atmosphere periodically.
Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet Mars possessed bodies of liquid water on the surface.
For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen. If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.
The Cell : The Hidden Kingdom
In a three-part series, Dr Adam Rutherford tells the extraordinary story of the scientific quest to discover the secrets of the cell and of life itself. Every living thing is made of cells, microscopic building blocks of almost unimaginable power and complexity.
The first part explores how centuries of scientific and religious dogma were overturned by the earliest discoveries of the existence of cells, and how scientists came to realize that there was, literally, more to life than meets the eye.
The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular (consist of a single cell).
Other organisms, such as humans, are multicellular. Humans have about 100 trillion or 1014 cells; a typical cell size is 10 µm and a typical cell mass is 1 nanogram. The largest cells are about 135 µm in the anterior horn in the spinal cord while granule cells in the cerebellum, the smallest, can be some 4 µm and the longest cell can reach from the toe to the lower brain stem (Pseudounipolar cells).
The largest known cells are unfertilised ostrich egg cells which weigh 3.3 pounds. In 1835, before the final cell theory was developed, Jan Evangelista Purkyně observed small "granules" while looking at the plant tissue through a microscope.
The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.
A new planet named Gliese 581 d, (which is an extrasolar
planet orbiting the red dwarf star Gliese 581) may contain life since it is within the habitable zone.
Conditions on the other terrestrial planets, Mercury and Venus, appear to be too harsh to support life as we know it.
But it has been conjectured that Europa, the fourth-largest moon of Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.
Recently, the team of Stéphane Udry have discovered a new planet named Gliese 581 d, which is an extrasolar planet orbiting the red dwarf star Gliese 581. Gliese 581 d appears to lie in the habitable zone of space surrounding the star, and therefore could possibly host life as we know it.