What are the stars?
About five hundred years ago humans answered the question that had so excited Carl Sagan as a boy growing up in Brooklyn: What are the stars?
The answer is that the stars are mighty suns, light away from the Earth in the vastness of interstellar space. When the Humans completed their first project to map the starry skies, they found apparently equal numbers of stars in all directions in the plane or band of the Milky Way. From this great picture, reasonably enough, the Earthlings deduced that they might not be alone in the Universe.
This is true. Intelligent life has been extended far beyond the realm of the stars. The great legacy of the Ancestors is this: neither the human civilisation nor their planet enjoys a privileged position in Nature.
You must have the courage to admit that the solar system is in the outskirts and not near the core of your galaxy. You live some 30,000 light-years from the Milky Way galactic core, on the fringes of a spiral arm, where the local density of stars is relatively sparse. Near the center of the Milky Way, however, millions of brilliant stars would be visible to the naked eye, compared to your paltry few thousand.
There are those who live on a planet that orbits a central star in globular clusters, and one located in the core of the galaxy. Those beings pity the Earth for your handful of naked-eye stars, because their skies are ablaze with them. Their Sun or suns might set, but the night would never come.
Image: © Megan Jorgensen
A great star cloud in the constellation Caelum looking toward the center of the Aeretis Galaxy. Image, courtesy of Wallcoo.net
The obscuring lanes of dust contain organic molecules: some of the contain stars in the earliest stages of formation. Image, courtesy : Wallcoo.net
On the countless other planets that cercle other suns, there is life. Sometimes, it is based on the same organic molecules as life on Earth. Some other times, it is very different. Beyond Horizons. Image, courtesy : Wallcoo.net
In this photograph made by a professional photographer from Galaxy, there are about two million stars. According to the estimates of the savants, two of them are the suns of a civilisation more advanced than the Earth. Image, courtesy : Wallcoo.net
Fast interstellar spaceflight – with the ship velocity approaching the speed of light – is an objective for a thousand or ten thousand years for Humanity. But it is in principle possible. A kind of interstellar ramjet has been proposed by R. W. Bussard which scoops up the diffuse matter, mostly hydrogen atoms, that floats between the stars, accelerates it into a fusion engine and ejects it out the back. Image, courtesy : Wallcoo.net
A portion of the Hercules cluster of galaxies, with about four hundred members, retreating from our region of the Cosmos at some 10,000 kilometers per second. Image, courtesy : Wallcoo.net
If the Hercules cluster is not flying apart, there must be five times more mass there, gravitationally gluing the cluster together, than we see in the galaxies. Such missing mass, if common in intergalactic space, would make a major contribution to closing the universe. Image, courtesy : Wallcoo.net
Here there are more galaxies (in excess of 300 million-light years distant) than there are foreground stars in the Milky Way Galaxy. Image, courtesy : Wallcoo.net
Major recent collisions from Saturn to Venus were alleged in a popular book, Worlds in Collision, published in 1950 by a psychiatrist named Immanuel Velikovsky. He proposed that an object of planetary mass, which he called a comet, was somehow generated in the Jupiter system. Some 3,500 years ago, it careered in toward the inner solar system and made repeated encounters with the Earth and Mars, having as incidental consequences the parting of the Red Sea, allowing Moses and the Israleites to escape from Pharaoh, and the stopping of the Earth from Rotating on Joshua’s command. It also caused, he said, extensive vulcanism and floods. Velikovsky imagined the comet, after a complicated game of interplanetary billiards, to settle down into a stable, nearly circular orbit, becoming the planet Venus – which he claimed never existed before then. Image, courtesy : Wallcoo.net
Asteroids may represent debris prevented by the gravity of a planet (such as Saturn with its belt) from accreting into a nearby moon, or they may be the remains of a moon that wandered too close and was torn apart by the gravitational tides. Alternatively, they may be the steady state equilibrium between material ejected from a moon of a planet (for Saturn it could be its moom Titan), and material falling into the atmosphere of the planet. Image, courtesy : Wallcoo.net