Dark Nights of the Universe, co-authored with Daniel Colucciello Barber, Nicola Masciandaro, Alexander R. Galloway and François Laruelle. [NAME] Publications, 2013. ISBN 978-0984056675.

The IAU defines a true planet as a body that circles the sun without being some other object's satellite; is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star); and has "cleared its neighborhood" of most other orbiting bodies. The Oort Cloud lies well past the Kuiper Belt, considered to be located between 2,000 and 5,000 astronomical units (AU) from the sun. The outer edge of the Oort Cloud may reach as far as 10,000 up to 100,000 AU from the sun. One AU is equal to approximately 93,000,000 miles (150 million kilometers). The Oort Cloud is home to billions, or even trillions of objects, according to NASA Science. Solar system formation and discovery If it occurred, this period of heavy bombardment lasted several hundred million years and is evident in the cratering still visible on geologically dead bodies of the inner Solar System such as the Moon and Mercury. [2] [77] The oldest known evidence for life on Earth dates to 3.8billion years ago—almost immediately after the end of the Late Heavy Bombardment. [78] Over the course of the Solar System's evolution, comets were ejected out of the inner Solar System by the gravity of the giant planets and sent thousands of AU outward to form the Oort cloud, a spherical outer swarm of cometary nuclei at the farthest extent of the Sun's gravitational pull. Eventually, after about 800 million years, the gravitational disruption caused by galactic tides, passing stars and giant molecular clouds began to deplete the cloud, sending comets into the inner Solar System. [81] The evolution of the outer Solar System also appears to have been influenced by space weathering from the solar wind, micrometeorites, and the neutral components of the interstellar medium. [82] The 0.1% of matter that remained orbited around the Sun, causing this randomly shaped gas cloud to form a flat disc shape. This flat disc, called the protoplanetary disc, was where the planets formed.' The formation of planetsIf the reader is already vaguely familiar with horror literature and the history of philosophy, then this book shouldn’t pose too much of a challenge. If, however, one is completely uninterested in the connections between philosophy, horror, and mystical theology, then this book will probably not engage your interest at all. Yet, even if you are incredibly engaged and interested in this topic, you might still be disappointed by the repetitiveness of his analysis in this volume.

See the entry "Biomedia" in Critical Terms for Media Studies, eds. W.J.T. Mitchell & Mark Hansen (University of Chicago Press, 2010). Hubble image of protoplanetary discs in the Orion Nebula, a light-years-wide stellar nursery probably very similar to the primordial nebula from which the Sun formed Yes, so many! If you had asked anyone just 30 years ago, the answer would have been "we don’t know". But since then we have discovered already more than 5,000 planets orbiting stars other than our sun (so-called exoplanets). And since often we find multiple of them orbiting the same star, we can count about 4,000 other solar systems. Do solar systems move? Within 50million years, the temperature and pressure at the core of the Sun became so great that its hydrogen began to fuse, creating an internal source of energy that countered gravitational contraction until hydrostatic equilibrium was achieved. [29] This marked the Sun's entry into the prime phase of its life, known as the main sequence. Main-sequence stars derive energy from the fusion of hydrogen into helium in their cores. The Sun remains a main-sequence star today. [30] The evolution of moon systems is driven by tidal forces. A moon will raise a tidal bulge in the object it orbits (the primary) due to the differential gravitational force across diameter of the primary. If a moon is revolving in the same direction as the planet's rotation and the planet is rotating faster than the orbital period of the moon, the bulge will constantly be pulled ahead of the moon. In this situation, angular momentum is transferred from the rotation of the primary to the revolution of the satellite. The moon gains energy and gradually spirals outward, while the primary rotates more slowly over time.The Exploit: A Theory of Networks, co-authored with Alexander R. Galloway. University of Minnesota Press, 2007. ISBN 978-0816650446. The sun accumulated about 99% of the available matter and the remaining material further from the sun formed smaller clumps inside the spinning disk. Some of these clumps gained enough mass that their gravity shaped them into spheres, becoming planets, dwarf planets and moons. Other leftover pieces became asteroids, comets and smaller moons that make up our solar system. T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, those planets accumulated little hydrogen and helium—not more than 1 M Earth each. Uranus and Neptune are sometimes referred to as failed cores. [43] The main problem with formation theories for these planets is the timescale of their formation. At the current locations it would have taken millions of years for their cores to accrete. [42] This means that Uranus and Neptune may have formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see Planetary migration below). [43] [44] Motion in the planetesimal era was not all inward toward the Sun; the Stardust sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt. [45] Astronomers had long suspected that a band of icy material known as the Kuiper Belt existed past the orbit of Neptune extending from about 30 to 55 times the distance of Earth to the sun, and from the last decade of the 20th century up to now, they have found more than a thousand of such objects. Scientists estimate the Kuiper Belt is likely home to hundreds of thousands of icy bodies larger than 60 miles (100 km) wide, as well as an estimated trillion or more comets. One unresolved issue with this model is that it cannot explain how the initial orbits of the proto-terrestrial planets, which would have needed to be highly eccentric to collide, produced the remarkably stable and nearly circular orbits they have today. [49] One hypothesis for this "eccentricity dumping" is that terrestrials formed in a disc of gas still not expelled by the Sun. The " gravitational drag" of this residual gas would have eventually lowered the planets' energy, smoothing out their orbits. [50] However, such gas, if it existed, would have prevented the terrestrial planets' orbits from becoming so eccentric in the first place. [35] Another hypothesis is that gravitational drag occurred not between the planets and residual gas but between the planets and the remaining small bodies. As the large bodies moved through the crowd of smaller objects, the smaller objects, attracted by the larger planets' gravity, formed a region of higher density, a "gravitational wake", in the larger objects' path. As they did so, the increased gravity of the wake slowed the larger objects down into more regular orbits. [52] Asteroid belt [ edit ]