In astronomy, the passage of a body across a meridian or the visible part of a larger body, such as Mercury or Venus crossing the solar disc or Jupiter's moons passing in front of the planet, as seen from the point of the observer (Earth in most cases). If the transit involves an object that's visually larger passing before a smaller one, we have an eclipse (for the sun or the moon) or an occultation (for any other satellite or a star).


In astrology, the passing of a planet over a significant point in a chart. Such significant points can be other planets, cusps of houses or zodiac signs and other points which an astrologer considers relevant. Transits always refer to a previously cast chart.

For example, if a chart contains Jupiter at 8°15' of Taurus (8 Taurus 15 in astrological jargon) and Mars in the course of its movement through the zodiac passes through (transits) that position, we say that Mars is transiting conjunct Jupiter. If Mars were passing through 8°15' of Scorpio, a distance of 180° from the previous point, we'd be saying that Mars is transiting opposite Jupiter. Other aspects are treated the same way. This is not the same as a transit in the astronomical sense since declination is not taken into account.

Non-planetary points can only be transited; only planets can transit something. When a planet's course comes full circle and it transits its position in a reference chart, such as a natal chart, it's called a return, e.g. a solar return.

In land surveying, an instrument used to measure angles and approximate distances. Transits typically consist of a telescope, with accurate cross hairs, mounted on a ring with vernier scales that measure angles in degrees and minutes (a minute is a sixtieth of a degree).

The scales can be locked and unlocked, allowing angles to be "turned" multiple times in multiple directions to check for error and squeeze the maximum accuracy out of the instrument.

To measure distances, two particular marks on the cross hairs of the transit are used. Above and below the center, along the vertical cross hair are two additional horizontal marks. These have been set such that they mark off a very particular angle. At a distance, if the pole being looked at has a single foot falling between the two hairs, then the pole is 100 feet away (usually, a level rod is used for this purpose, since it has feet and tenths marked off on it). If it has 2.34 feet falling between the hairs, it is 234 feet away, and so on. The process of measuring distances this way is only accurate to about 1 part in 100, but this is good enough for certain types of activity. Called "shooting stadia", this is a very quick way to measure distances when great accuracy is not required (such as a "topo" survey of a yard, where features such as trees and bushes are marked on a map).

In modern circumstances, transits are only used for short distances and work that doesn't require great accuracy. They've been supplanted by theodolites that measure angles much more accurately.

See: land surveying.

A Doctor Who novel, written by Ben Aaronovitch. The tenth of Virgin Publishing's New Adventures.

Previous story: Love and War | Next story: The Highest Science

WARNING! LOTS OF SPOILERS AHEAD!

Regular characters

The Seventh Doctor

Benny

Recurring characters

Kadiatu Lethbridge-Stewart

Major developments

The TARDIS remains infected (since Cat's Cradle: Witch mark). The Doctor meets Kadiatu Lethbridge-Stewart, who has been collecting information on the Doctor's appearances on Earth, and who later builds her own time machine and leaves Earth. Deciding that too much is known of him on Earth, the Doctor arranges to have all the information on his activities on Earth erased.

My opinion

Ben Aaronovitch, apparently, has a few problems meeting deadlines. Rumour has it that he delivered the first draft of Transit to the publishers only days before the final manuscript had to be sent to the printers, and the final published version is in fact the first draft with only a hurried edit for sense and literals. If this story is true, then Aaronovitch's meticulous world-building in this book is truly amazing. Aaronovitch has built this world incredibly convincingly. It is a world still recovering from a massive war with the Ice Warriors, and the fact that it is such bleak and violent world may be the reason many lovers of the relatively innocent tv show found this such a shock to the system. On the original show they never had as a character a prostitute who chewed kola nuts to "keep her awake and take the semen taste out of her mouth".

This is a book that has polarised opinion about it. It usually comes right near the bottom in many surveys of favourite stories, but is cited by many later Doctor Who authors as a major influence. Personally, I think it's brilliant, and easily one of the best of the early Doctor Who books. It certainly owes a lot to William Gibson and cyberpunk in general, but carries it off so well that I can certainly forgive it that.

Quick outline

The solar system in 2119 is fully colonised by Earth, and linked by a subspace mass transit system. On the thirtieth anniversary of Earth's victory over Mars, the transit authority (the STS) plans to open a tunnel to Acturus, incorporating Earth colonies in other star systems into the transit system. However, when the tunnel is opened something from the other side of the carrier wave smashes through, and tears right through the Central Line killing everyone it its path. At about this time, the Doctor and Benny arrive at King's Cross station, and while the Doctor manages to fall to safety, Benny and the TARDIS are swept away to the end of the line, Lowell Depot on Pluto. Benny survives the journey but is possessed by the force that swept her away. The tunnel to Arcturus is quickly shut down, but the transit system has already been invaded.

The Doctor meets Kadiatu, a university student who, the Doctor soon discovers, has been collecting information on the Doctor and time travel. The Doctor also learns that she is a product of genetic modification research, created to be a perfect soldier but rescued from her creators and raised by an African descendant of the Doctor's old friend Brigadier Alistair Lethbridge-Stewart. The Doctor decides to keep an eye on her, and she also wishes to stay close to him to learn more of time travel, and so they look for Benny together. Meanwhile, other users of the transit system are being affected by the invading force, and being converted into strange cybernetically-enhanced creatures.

Benny, affected by the force possessing her, meets and befriends Zamina, a prostitute living and working at the Stop, the slum neighbourhood around Lowell Depot on Pluto. Benny convinces Zamina to take her to the leader of one of the local gangs, who she convinces she can help take control of the Stop. It is all a ruse, however, to cause a major disruption, and Benny's manipulations result in a major outbreak of gang warfare. The Stop is evacuated, and, after an encounter with the Doctor and Kadiatu in which Benny nearly kills the Doctor, Benny and Zamina are evacuated to Mars.

Losing track of Benny, the Doctor and Kadiatu, along with Kadiatu's new lover Blondie, go to the Doctor's house on Allen Rd, in Kent, where the Doctor considers the situation. Learning about strange things happening in the transit system before the tunnel to Arctutus was opened he deduces that the transit system, having grown so complicated it now resembles a neural network, has evolved its own intelligence. He contacts this new sentience, and learns that the invading force is a sort of computer virus from another dimension. Meanwhile, Benny's distance from the transit system has apparently weakened the invading force's control of her mind, and she is able to get a message to the Doctor telling him where she is.

The Doctor and Kadiatu follow Benny to Mars, where she attempts to reach the STS control centre, but is stopped by Kadiatu, who kills her. It turns out, however, that they were following not Benny, but one of the modified transit users made to look like Benny and sent as a decoy. The Doctor and Kadiatu return to Earth but are too late to prevent Benny achieving her goal. Another of the modified passengers is sent to overload STS's reactors, resulting in a flood of power and the tunnel to Arcturus is opened again.

The Doctor travels through the transit system to the entrance of the Arcturus tunnel, where he arrives in time to see Benny possessed by the full intelligence of the invading force, of which only a portion had arrived last time the tunnel was open. The Doctor is able to use a blast of energy from the TARDIS to send the nameless intelligence (which the Doctor has dubbed "Fred") back down the tunnel to its own dimension, taking Benny with it. The Doctor follows and a battle of will ensues in Fred's home dimension, where perception shapes reality. The Doctor is on the verge of being defeated by Fred when Kadiatu arrives in the form of a black leopard and attacks Fred. While Fred is distracted the Doctor is able, with the additional help of the intelligence of the transit system, to force Fred out of Benny's mind. The Doctor, Benny and Kadiatu are able to escape Fred's dimension and return to Earth victorious just before the tunnel collapses.

Later, having decided that too much is known about him on Earth, the Doctor visits the computer system where most of Earth's historical records are kept, and arranges to have all record of his activities on Earth removed (in the process befriending the newly-evolved artificial intelligence, and giving it tips on how to get along with humans; the intelligence names itself FLORANCE, hires itself some lawyers and declares its independence), and the Doctor and Benny resume their travels. Later still, Kadiatu completes her time travel research, builds her own time machine and leaves Earth.


Sources

http://www.drwhoguide.com/who.htm
http://www.gallifreyone.com/timeline.htm

The astronomical term "transit", which can mean the passing of any body over any other body or through any point, can most often be applied to the time that a body transits the meridian.

This is somewhat confusing, because a transit is often used to refer to such highly unusual events as Venus crossing the disc of the sun, but it can also be used to describe the very normal event of Venus crossing the meridian of the sky, which it does once a day.

For most people, knowing the transit time of a planet is important because at transit, a planet is the highest in the sky, and therefore most free of light pollution or haze. Knowing the transit time, along with the rising and setting time allows an observer to also estimate where it would be at other times of the night, which makes identification much easier.

Trans"it (?), n. [L. transitus, from transire to go over: cf. F. transit. See Transient.]

1.

The act of passing; passage through or over.

In France you are now . . . in the transit from one form of government to another. Burke.

2.

The act or process of causing to pass; conveyance; as, the transit of goods through a country.

3.

A line or route of passage or conveyance; as, the Nicaragua transit.

E. G. Squier.

4. Astron. (a)

The passage of a heavenly body over the meridian of a place, or through the field of a telescope.

(b)

The passage of a smaller body across the disk of a larger, as of Venus across the sun's disk, or of a satellite or its shadow across the disk of its primary.

5.

An instrument resembling a theodolite, used by surveyors and engineers; -- called also transit compass, and surveyor's transit.

⇒ The surveyor's transit differs from the theodolite in having the horizontal axis attached directly to the telescope which is not mounted in Y's and can be turned completely over about the axis.

Lower transit Astron., the passage of a heavenly body across that part of the meridian which is below the polar axis. -- Surveyor's transit. See Transit, 5, above. -- Transit circle Astron., a transit instrument with a graduated circle attached, used for observing the time of transit and the declination at one observation. See Circle, n., 3. -- Transit compass. See Transit, 5, above. -- Transit duty, a duty paid on goods that pass through a country. -- Transit instrument. Astron. (a) A telescope mounted at right angles to a horizontal axis, on which it revolves with its line of collimation in the plane of the meridian, -- used in connection with a clock for observing the time of transit of a heavenly body over the meridian of a place. (b) Surv. A surveyor's transit. See Transit, 5, above. -- Transit trade Com., the business conected with the passage of goods through a country to their destination. -- Upper transit Astron., the passage of a heavenly body across that part of the meridian which is above the polar axis.

 

© Webster 1913.


Trans"it, v. t. Astron.

To pass over the disk of (a heavenly body).

 

© Webster 1913.

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