Astronomy and related astronomical terms

A zodiacal constellation in the northern hemisphere near Orion, represented as a bull. The sun passes through Taurus from mid-May to late June.

The movement of plates that make up the lithosphere of a planet.

Such movements produce fold mountains and other surface features.

A small, rounded glassy stone, found in certain regions of the earth; such as, Australasia.

Tektites are probably the scattered drops of molten rock thrown out by the impact of a large meteorite.

Mercury, Venus, Earth, and Mars.

The shadow-line boundary between night and day on a planet or moon.

The type of electromagnetic radiation emitted when electrons and atoms forming part of a hot gas interact by collisions; the resulting radiation is continuous, as opposed to discrete, line emission.

Nuclear fusion that occurs at extremely high temperatures.

1. The minimum distance to which a large satellite can approach its primary body without being torn apart by tidal forces. 2. The force arising from differences in the strength of gravity experienced over different parts of an object.

1. The effect arising from the differential gravitational effect of one body on another.

This usually manifests itself in the distortion of the shape of the body; especially, the surface layers.

2. Periodic changes in the shape of a planet, moon, or star caused by the gravitational attraction of a body near it.

The moon tugs on earth's oceans, causing high and low tides; while Jupiter's gravitational attraction on its moon Io causes ground tides; and when two stars are very close together, they pull each other's atmospheres into distorted shapes.

The largest moon of the planet Saturn.

It was discovered in 1655 by the Dutch mathematician and astronomer Christian Huygens, and is the second largest moon in the solar system. Ganymede, of Jupiter, is larger.

1. An empirical rule giving the approximate distances of planets from the sun.

It was first announced in 1766 by the German astronomer Johann Daniel Titius but was popularized only from 1772 by his countryman Johann Elert Bode.

Once thought to have some significance regarding the formation of the solar system, Bode’s law is now generally regarded as a numerological curiosity with no known justification.

2. An empirical law that generates the distances of planets and the position of the minor planet belt from the sun in astronomical units.

An object formed by joining the two ends of a cylinder producing a doughnut shape with a circular cross-section.

A magnetic field inside the orbit is always twice as strong as the magnetic field on the orbit, the radius of the orbit remains constant, so that the acceleration chamber can be made in the shape of a torus, or doughnut.

The poles of the magnet are tapered to cause the field near the orbit to weaken with increasing radius.

The moment during a total solar eclipse during which the sun completely disappears from view.

The light of totality is much brighter than that of the full moon but is quite different in color. The duration of totality is brief, typically lasting two to five minutes.

1. The crossing of a small celestial body in front of a larger one.

Venus and Mercury are in transit across the disk of the sun when seen from the earth.

2. The passage across the observer's meridian of a celestial body, or the crossing of the face of one body; for example, the sun, by the path of another; for example, Mercury or Venus, from the observer's viewpoint.

A group of minor planets that are clustered around two of the Lagrangian positions of the Jupiter-sun system; that is, a point in space at which a small body, under the gravitational influence of two large ones, will remain approximately at rest relative to them.

The first Trojan was Achilles, discovered in 1906.

These minor planets revolve around the sun in the Lagrangian points of Jupiter’s orbit and they are positions where a small body can be held, by gravitational forces, at one point of an equilateral triangle whose other points are occupied by Jupiter and the sun.

About forty Trojan planets are known; Achilles, the first, was discovered by Max Wolf in 1906. Of the named Trojans, Achilles, Hector, Nestor, Agamemnon, Odysseus, Ajax, Antilochus, Diomedes, and Menelaus are near the Lagrangian point 60° ahead of Jupiter. Patroclus, Priamus, Aeneas, Anchises, and Troilus are about 60° behind Jupiter.