Chapter VIII · Chapter 8

used before a singular noun to mean one of a group, when it is not a particular one

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

on the subject of; concerning

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

equally

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

(quantifier) used with either mass or count nouns to indicate the whole number or amount of or every one of a class

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

the act of binding yourself (intellectually or emotionally) to a course of action

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

used to join words or parts of a sentence that go together

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

one more of the same kind, or a different one

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

any thing at all

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

formal attendance (in court or at a hearing) of a party in an action

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

the form of “be” used with you, we, they, or a plural noun

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

at the same time that; because; in the way that

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

in or near a particular place or position

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

plural of “body” — the entire physical structure of an organism (an animal, plant, or human being)

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

a written work or composition that has been published (printed on pages bound together)

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used to introduce something that contrasts with what came before

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

showing who or what does the action

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

past form of “call” — assign a specified (usually proper) proper name to

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

definite but not specified or identified

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

cause to change; make different; cause a transformation

From this reading Even as we watch them they grow and change, and then diminish in splendour.

a collection of things sharing a common attribute

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

plural of “comet” — (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

the act of drawing spatially closer to something

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

carefully weighed

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

(plural) the deepest and most remote part

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

decrease in size, extent, or range

From this reading Even as we watch them they grow and change, and then diminish in splendour.

plural of “direction” — a line leading to a place or point

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

Dictionary entry pending editorial verification. Tap Listen to hear the word.

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

divisible by two

From this reading Even as we watch them they grow and change, and then diminish in splendour.

at any time

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

all things; all of a situation

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

drained of energy or effectiveness; extremely tired; completely exhausted

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

the organ of sight

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

to a considerable degree; very much

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

gleam or glow intermittently

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

intended to be given to, or used by, somebody

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

change location; move, travel, or proceed, also metaphorically

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

the act of departing

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

relatively large in size or number or extent; larger than others of its kind

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

pass into a condition gradually, take on a specific property or attribute; become

From this reading Even as we watch them they grow and change, and then diminish in splendour.

used with a past participle to form the perfect tenses

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

characteristic of humanity

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

inside something, or within a place, period, or state

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

having no limits or boundaries in time or space or extent or magnitude

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

the form of “be” used with he, she, it, or a singular noun

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a thing, animal, or idea already mentioned

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used when the thing doing the action is also its object

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

inflected form of “learn” — gain knowledge or skills

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used to form the comparative of some adjectives and adverbs

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

produced by a manufacturing process

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

plural of “member” — one of the persons who compose a social group (especially individuals who have joined and participate in a group organization)

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

the location of something surrounded by other things

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

(comparative of “much” used with mass nouns) a quantifier meaning greater in size or amount or extent or degree

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

not ever; at no time in the past or future

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

not any; not one

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used to make a word, phrase, or sentence negative

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

belonging to, or connected with, somebody or something

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used to join alternatives or possibilities

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

plural of “orbit” — the (usually elliptical) path described by one celestial body in its revolution about another

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a soldier who serves as an attendant to a superior officer

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

belonging to the speaker and others

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

not allowed to continue to bat or run

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

have ownership or possession of

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

a point located with respect to surface features of some region

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

plural of “planet” — (astronomy) any of the nine large celestial bodies in the solar system that revolve around the sun and shine by reflected light

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

in accordance with fixed order or procedure or principle

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a property of polygons: the property of having equal sides and equal angles

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

not arrogant or presuming

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

tending to return to an earlier state

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

a charge of ammunition for a single shot

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

plural of “satellite” — man-made equipment that orbits around the earth or the moon

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

perceive by sight or have the power to perceive by sight

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

third-person singular of “seem” — give a certain impression or have a certain outward aspect

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

put into a certain place or abstract location

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

plural of “shape” — any spatial attributes (especially as defined by outline)

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

marked by exceptional merit

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

plural of “size” — the physical magnitude of something (how big it is)

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

for that reason; with the result that

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

relating to or derived from the sun or utilizing the energies of the sun

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

on certain occasions or in certain cases but not always

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

the unlimited expanse in which everything is located

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a quality that outshines the usual

From this reading Even as we watch them they grow and change, and then diminish in splendour.

being definitely out of the ordinary and unexpected; slightly odd or even a bit weird

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

the star that is the source of light and heat for the planets in the solar system

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

instrumentality that combines interrelated interacting artifacts designed to work as a coherent entity

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

used before a noun that is already known, already mentioned, or the only one of its kind

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

the people or things already mentioned, as the object

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

subsequently or soon afterward (often used as sentence connectors)

From this reading Even as we watch them they grow and change, and then diminish in splendour.

in or at that place or location

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

the plural of “this”: the people or things near, or just mentioned

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

the people, animals, or things already mentioned, as the subject

From this reading Even as we watch them they grow and change, and then diminish in splendour.

used for a person or thing that is near, or that has just been mentioned

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a more or less definite period of time now or previously present

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

used before the base form of a verb to make the infinitive

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

two times

From this reading These strange visitors are called comets, and are of all shapes and sizes and never twice alike.

being or moving higher in position or greater in some value; being above a former position or level

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

plural of “visitor” — someone who visits

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

a message informing of danger

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

look attentively

From this reading Even as we watch them they grow and change, and then diminish in splendour.

the speaker together with one or more other people

From this reading SHINING VISITORS Our solar system is set by itself in the midst of a great space, and so far as we have learnt about it in this book everything in it seems orderly: the planets go round the sun and the satellites go round the planets, in orbits more or less regular; there seems no place for anything else.

suggesting the operation of supernatural influences

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

at the time that

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

in or at the place that

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

used to introduce a clause giving more about a thing just mentioned

From this reading But when we have considered the planets and the satellites, we have not exhausted all the bodies which own allegiance to the sun.

used to talk about the future, or about willingness

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

in the company of; together with

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.

not having, not using, or not accompanied by

From this reading There is another class, made up of strange and weird members, which flash in and out of the system, coming and going in all directions and at all times--sometimes appearing without warning, sometimes returning with a certain regularity, sometimes retiring to infinite depths of space, where no human eye will ever see them more.