There is also some reason to believe that amino acids lead to the formation of purines and pyrimidines, which are in turn building blocks for nucleic acids. Proteins and nucleic acids are the two fundamental constituents of life as we know it on earth; hereditary materials such as genes and chromosomes are composed perhaps exclusively of nucleic acids and proteins.
In addition, enzymes, which catalyze slow chemical reactions and thereby make complex life forms possible, are always proteins. Experiments of comparable importance to those of Miller have been performed by S. Fox applied heat, in the range between and degrees Centigrade, to simple molecules, such as those synthesized by Miller.
This simple procedure produced small amounts of complex organic molecules that happen to be widely distributed in all terrestrial organisms. In particular, Fox has produced ureidosuccinic acid, a key intermediary in the synthesis of nucleic acids.
The temperatures required by Fox can easily be supplied by radioactive heating of the crust of the planet. There is evidence that such radioactive heating is a normal part of the early evolution of all planets.
Now it is really striking that the molecules produced by Miller and Fox are precisely the molecules necessary to form life as we know it. Almost no molecules were produced which are not fundamentally involved in modern terrestrial organisms. The processes described by Miller and Fox would probably occur on at least one planet of each star of moderate temperature. All that is required is a way of collecting the molecules produced by these processes into one place where they can interact.
A liquid medium on the surface of the planet serves this purpose admirably. Molecules produced in the atmosphere would fall into these bodies of liquid, and molecules produced on land by the application of heat would also be washed into them. Although seas of liquid ammonia or hydrofluoric acid would serve, it can be shown that seas of water would be most efficient in collecting and preserving the bio-molecules.
The one planet in each system that we are considering probably possessed liquid water seas early in its history, and therefore on such planets the production of proteins and nucleic acids may be expected. Now proteins and nucleic acids have some unusual properties; so far as we know, ones not found in any other molecules.
They can form a new molecule which not only can construct other identical molecules from the matter floating in the sea around it, but which if changed in some way can also construct copies of its changed structure. Such a mutating, self-reproducing molecule or collection of molecules must undergo natural selection.
For these reasons, it must be identified as the first living being on the planet in question. Thus, there may be million planets in this galaxy alone on which flourish organisms at least biochemically akin to ourselves. For five years he was the art director at the National Air and Space Museum. Miller likened the work of being a space artist to the forensic and paleontological arts, both of which require their practitioners to rely on small bits of information—bones, fossils, other clues—to imagine what something once looked like.
Or, in this case, what it would look like, were the solar system radically different, and Jupiter our very close neighbor. Space artists have in fact been an important factor in the history of the development of space flight and have additionally inspired hundreds of people to pursue careers in astronomy or astronautics.
No offense to our moon, but imagine looking up in the sky and seeing this:. The Earth rising above the Moon, as seen by the Apollo 8 astronauts on December 24, , while they orbited the Moon. Borders that once rendered division vanished.
All of humanity appeared joined together on this glorious-but-fragile sphere. The discovery of another planet that bears signs of life would transform our understanding of biology and of ourselves. It would be among the most important discoveries ever made. Astronomy stirs the imagination. It inspires us to learn more about the world and about the universe in which we live. A single astronomical image—like the photograph of Earth rising above the Moon taken from Apollo 8 or the image of the stellar nursery in the Eagle Nebula from the Hubble Space Telescope—can have a profound and long-lasting impact.
Astronomical themes also appear in many popular movies, and many terms from the field—such as quasar and black hole—have entered our common vocabulary. Astronomy is also an inherently international endeavor. Modern telescopes are so large and complicated that they require collaboration among nations.
And all people share the night sky, no matter what else divides us. Which is not a method astronomers use to detect a planet? Are there other planetary systems like ours? Ready to take the quiz?
How easy is it to find planets around other stars? There are many unknowns regarding the potentially habitable exoplanet Keplerf, but it may have similar light from its star and gravity as Earth. Living on an Alien Planet: Exoplanet Keplerf: Infographic At last humans are able to make educated guesses about what living on alien worlds might be like. Here's what we know about the alien planet Keplerf.
Earth-Size Planet Keplerf, a Possibly Habitable Alien World: Gallery The alien planet Keplerf is a planet only slightly larger than Earth orbiting inside the habitable zone of its red dwarf star.
See images and photos of the Keplerf planet discovery in this Space. Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community space.
Tariq is the Editor-in-Chief of Space. He became Space. Before joining Space. He is also an Eagle Scout yes, he has the Space Exploration merit badge and went to Space Camp four times as a kid and a fifth time as an adult. To see his latest project, you can follow Tariq on Twitter. Tariq Malik.
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