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Fossil is a science fiction book by American writer Hal Clement, as part of the Isaac's Universe series. It was first printed in November 1993. [1] Copyright was reserved to him under his real name, Harry C. Stubbs, and the company he associated himself with, Tomorrow, Inc.
On a medium-sized, low-gravity planet with a very slow rotational period, the side that is farthest from the sun is always a very hard mixture of frozen carbon dioxide, rock hard ammonia, and solid water ice, and the side that is closest, a sea of turbulent liquids and icebergs. The planet rotates so slowly that the part that is half ice and half ocean is constantly beset with troubling weather conditions, ranging from blizzards to unanticipated ice melts and earthquakes. It takes centuries if not thousands of years for the wobbling of the planet on the ecliptic to melt certain parts of the planet. Even still, it is possible for the planet to have become locked in orbit, so the farthest side never melts. The tidal locking of the planet may have occurred hundreds of millions of years ago, and seasons appear to be limited to the slight wobbling of the planet on the ecliptic. Far from being an uninteresting planet, the ecliptic along which the planet travels is also tilted. Most of the colonies are located along the "coast" - the place in a murky half-shadow of constant night and constant day.
Scientific researchers from all kinds of alien species from all over the known universe have come to this planet to engage in an arduous archaeological expedition to unearth mysterious fossils from deep within the multi-kilometer thick icy crust. They have dug so deep that it is generally considered dangerous to dig any deeper. On some of the worlds around the galaxy, mysterious relics are found from an earlier civilization that no longer exists. Since the planet has almost no rock at its core, and enjoyed a rotational period for the first couple billion years of its existence, there is probably nothing to find here, short of fossils of earlier species once flourishing on the planet, but now extinct.
Harry Clement Stubbs, better known by the pen name Hal Clement, was an American science fiction writer and a leader of the hard science fiction subgenre. He also painted astronomically oriented artworks under the name George Richard.
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called nutation. In physics, there are two types of precession: torque-free and torque-induced.
Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite and the primary planet that it orbits. The acceleration causes a gradual recession of a satellite in a prograde orbit, and a corresponding slowdown of the primary's rotation. The process eventually leads to tidal locking, usually of the smaller body first, and later the larger body. The Earth–Moon system is the best-studied case.
2010: Odyssey Two is a 1982 science fiction novel by British writer Arthur C. Clarke. It is the sequel to his 1968 novel 2001: A Space Odyssey, though Clarke changed some elements of the story to align with the film version of 2001.
Rotation or rotational motion is the circular movement of an object around a central line, known as axis of rotation. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersecting anywhere inside or outside the figure at a center of rotation. A solid figure has an infinite number of possible axes and angles of rotation, including chaotic rotation, in contrast to rotation around a fixed axis.
Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked body possesses synchronous rotation, the object takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces Earth, although there is some variability because the Moon's orbit is not perfectly circular. Usually, only the satellite is tidally locked to the larger body. However, if both the difference in mass between the two bodies and the distance between them are relatively small, each may be tidally locked to the other; this is the case for Pluto and Charon, as well as for Eris and Dysnomia. Alternative names for the tidal locking process are gravitational locking, captured rotation, and spin–orbit locking.
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In particular, axial precession can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of approximately 26,000 years. This is similar to the precession of a spinning top, with the axis tracing out a pair of cones joined at their apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis—nutation and polar motion—are much smaller in magnitude.
Mesklin is a fictional supergiant planet created by Hal Clement and used in a number of his hard science fiction stories.
In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon perceived by Earth-bound observers and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see slightly different hemispheres of the surface at different times. It is similar in both cause and effect to the changes in the Moon's apparent size due to changes in distance. It is caused by three mechanisms detailed below, two of which cause a relatively tiny physical libration via tidal forces exerted by the Earth. Such true librations are known as well for other moons with locked rotation.
Orcus is a large trans-Neptunian object and likely dwarf planet located in the Kuiper belt, with one large moon, Vanth. It has an estimated diameter of 870 to 960 km, comparable to the Inner Solar System dwarf planet Ceres. Orcus had been accepted by many astronomers as a dwarf planet, though as of 2024 that classification remains somewhat controversial. The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color, and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.
A synodic day is the period for a celestial object to rotate once in relation to the star it is orbiting, and is the basis of solar time.
Polar motion of the Earth is the motion of the Earth's rotational axis relative to its crust. This is measured with respect to a reference frame in which the solid Earth is fixed. This variation is a few meters on the surface of the Earth.
Cassini's laws provide a compact description of the motion of the Moon. They were established in 1693 by Giovanni Domenico Cassini, a prominent scientist of his time.
Fictional depictions of Mercury, the innermost planet of the Solar System, have gone through three distinct phases. Before much was known about the planet, it received scant attention. Later, when it was incorrectly believed that it was tidally locked with the Sun creating a permanent dayside and nightside, stories mainly focused on the conditions of the two sides and the narrow region of permanent twilight between. Since that misconception was dispelled in the 1960s, the planet has again received less attention from fiction writers, and stories have largely concentrated on the harsh environmental conditions that come from the planet's proximity to the Sun.
Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Polaris, Earth turns counterclockwise.
The Moon orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the stars in about 27.32 days and one revolution relative to the Sun in about 29.53 days. Earth and the Moon orbit about their barycentre, which lies about 4,670 km (2,900 mi) from Earth's centre, forming a satellite system called the Earth–Moon system. On average, the distance to the Moon is about 385,000 km (239,000 mi) from Earth's centre, which corresponds to about 60 Earth radii or 1.282 light-seconds.
Star Light is a science fiction novel by American writer Hal Clement. It is the sequel to one of Clement's earlier books, Mission of Gravity. The novel was serialized in four parts in Analog Science Fiction/Science Fact Magazine from June to September 1970. Star Light was first published as a paperback book by Ballantine Books in September 1971.
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object. It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars.
Isaac's Universe is a fictional universe created by Isaac Asimov for other science fiction writers to use as a setting. It introduces the collaborative science fiction universe created by Asimov which eventually resulted in five volumes: three short story collections and two novels. It was initiated by Martin H. Greenberg, who also edited and published its three short stories collection by Avon Books starting in 1990.
Axial parallelism is the characteristic of a rotating body in which the direction of the axis of rotation remains fixed as the object moves through space. In astronomy, this characteristic is found in astronomical bodies in orbit. It is the same effect that causes a gyroscope's axis of rotation to remain constant as Earth rotates, allowing the devices to measure Earth's rotation.