Furlongs per fortnight

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It's about the chains. Credit: Stilfehler.

Furlongs per fortnight is a problem set with a contained quiz that focuses on the fundamentals of observational and deductive astronomy. In the activity Energy phantoms you learned about the value of distance, or displacement, and motion, speed, velocity, and acceleration. Here, you can practice and test yourself on converting from units that may or have occurred in the literature to units popular today.



evaluation activity

Astronomical units[edit | edit source]

Notation: let the symbol indicate the Earth's radius.

Notation: let the symbol indicate the radius of Jupiter.

Notation: let the symbol indicate the solar radius.

Physical units[edit | edit source]

Both physics and astronomy use units and dimensions to describe observations.

Units of Physics and Astronomy
Dimension Astronomy Symbol Physics Symbol Conversion
time 1 day d 1 second s 1 d = 86,400 s[1]
time 1 "Julian year"[2] J 1 second s 1 J = 31,557,600 s
distance 1 astronomical unit AU 1 meter m 1 AU = 149,597,870.691 km[1]
angular distance 1 parsec pc 1 meter m 1 pc ~ 30.857 x 1012 km[1]

Theoretical units[edit | edit source]

Perhaps the first step in deciphering ancient presumably astronomical records is determining what the unit is.


  1. a series of interconnected rings or links usually made of metal,
  2. a series of interconnected links of known length, used as a measuring device,
  3. a long measuring tape,
  4. a unit of length equal to 22 yards. The length of a Gunter's surveying chain. The length of a cricket pitch. Equal to 20.12 metres. Equal to 4 rods. Equal to 100 links.
  5. a totally ordered set, especially a totally ordered subset of a poset,
  6. iron links bolted to the side of a vessel to bold the dead-eyes connected with the shrouds; also, the channels, or
  7. the warp threads of a web

is called a chain.

Def. a period of fourteen nights; two weeks is called a fortnight.

Def. a unit of length equal to 220 yards or exactly 201.168 meters, now only used in measuring distances in horse racing is called a furlong.


  1. a trench cut in the soil, as when plowed in order to plant a crop or
  2. any trench, channel, or groove, as in wood or metal

is called a furrow.

Def. the distance that a person can walk in one hour, commonly taken to be approximately three English miles (about five kilometers) is called a league.

Def. a period of seven nights; a week is called a sennight.


  1. any period of seven consecutive days,
  2. a period of seven days beginning with Sunday or Monday,
  3. a subdivision of the month into longer periods of work days punctuated by shorter weekend periods of days for markets, rest, or religious observation such as a sabbath, or
  4. seven days after (sometimes before) a specified date

is called a week.

Problem 1[edit | edit source]

A local farmer has spotted what she believes is an astronomical object moving in the sky at night.

As the ox-plow travels using the apparently fixed points of light in the night sky, the object has covered 0.214 furlongs in her field over 1.631 fortnights.

Her field is 16.421 furlongs from horizon to horizon in the direction the object is traveling. The amount of the total sky (360° if the Earth were not in the way) her field actually views in 10.123°.

How many arcseconds has the astronomical object traversed in the night sky?

How fast is the object traveling in degrees/hour?

If after the first night of travel, the object appears to cover about 0.250 less distance, is the object accelerating or decelerating and by how much in kilometers/sec2?

If the object turns out to be 0.313 of the mean distance to the Moon away, what are its actual speed and acceleration in km and sec?

Problem 2[edit | edit source]

Like the farmer in problem 1, a sailor aboard an oil tanker heading northeast across the mid-Atlantic has noticed an apparent astronomical entity traveling north against the fixed stars. Using another nearby ship, the sailor estimates that relative to those stars the entity has traveled 20,000 leagues due north along the surface of the ocean.

Using the radius of the Earth to the North Pole, how many arcseconds has the entity traversed, if the period of movement is a tunti?

What is the entity's speed in km/sec?

What is its speed in arcsecs per minute?

At the end of the observing period, the sailor notices the entity make a 22° change in direction to the east in about four diba'igaans.

If after the change in direction the entity is observed to be traveling at the same speed, what acceleration has been applied to the entity?

Problem 3[edit | edit source]

An astronaut on the surface of the Moon is observing the Earth at night. While watching the Earth she notices a source of visible white light traveling perpendicular to the direction of the Earth's rotation.

In the time it takes North America to rotate into view from just before it's visible the source travels a linear arc approximately equivalent to the arc from the Tropic of Cancer to the Tropic of Capricorn.

About how many arcminutes has the source traveled?

If it is as far away as the Earth from the Moon, what is its speed in km/hr?

Relative to the Earth's rotational axes, is the object traveling northward or southward?

Quiz[edit | edit source]


1 Yes or No, The furlong is a unit of time.


2 Which of the following are units of distance?


3 True or False, A hectare is a unit of weight.


4 Complete the text:

Match up the type of phenomenon with each of the possibilities below:
visible tracks such as a star trail - A
a cloud - B
bubbles - C
a grid of uninsulated electric wires - D
octagon - E
circumpolar trail - F


rotational pole



an arc


5 True or False, If a creature comes from 20,000 leagues under the sea it is actually a football player.


6 Four scores in time is eighty


7 True or False, A level grade is a slope of 12°.


8 Complete the text:

The 0.6m Tortugas Mountain Observatory is used to monitor the temporal changes in the

cloud deck and equatorial activity on


9 Yes or No, An event that occurred 2280 b2k actually happened at 80 BC.


10 An astronomical event occurred during the Cambrian, what does that mean?

students in the India must use Greenwich mean time
about 5 x 108 years ago
a high-powered robotic telescope was lost on the shuttle Cambrian
a student in Xinjiang has an abacus configured to the geologic time scale
on-site use of two high-powered telescopes is available
trilobites tried to communicate with Earth

11 True or False, A theoretical observatory decides which systems, for example, among virtual stellar systems, should be recognizable, and which not.


12 Various blue radiation observatories occur at different altitudes and geographic locations due to what effect?

the presence of oceans on the Earth
locally available carving tools
light pollution
most astronomical objects are observed at night
currently dormant volcanoes seldom erupt
human habitation increases near an astronomical observatory

13 True or False, The U.S. Virtual Astronomical Observatory (VAO) goal is to enable new science through efficient integration of distributed multi-temporal data.


14 Which of the following are temporal observatories in orbit around the Earth?

Chandra X-ray Observatory
Big Bear
the Hubble
Lomnický štít

15 True or False, A canton is used to keep track of femtoseconds.


16 Pressure is a measure of force per unit


17 True or False, The US Ground-based Electro-Optical Deep Space Surveillance (GEODSS) base at Diego Garcia is located 412 decameters off the coast of southern California.


18 Which of the following are characteristic of a volume?


19 True or False, There is a 101-cm telescope at Bisei Astronomical Observatory.


20 Which phenomenon are associated with acceleration?

a region of space where the interstellar medium is blown away by a supernova
a bubble
decreasing time

21 True or False, The Sudbury Neutrino Observatory is a 12-meter sphere filled with heavy water surrounded by light detectors located 2 km below the ground in Sudbury, Ontario, Canada.


22 Complete the text:

Match up the distance-time phenomena with the image:
line of sight - A
an origin - B
a displacement - C
one billion light years - D
measuring - E
acceleration - F
Celestial swiss cheese.

A beautiful galaxy.

An elliptical orbit.

Closer than a route.

It's about the chains.

Getting the numbers.


23 Yes or No, The Sphinx Observatory is at a location.


24 Acceleration is directly involved in which of the following astronomies?

cosmic-ray astronomy
infrared astronomy
neutrino astronomy
proton astronomy
ultraviolet astronomy
electron astronomy

25 True or False, An observatory is a place.


26 Which of the following are associated with mas?

under ice
proper motion
radial velocity
spectral type

27 True or False, Historically, observatories were as simple as having some alignments on astronomical phenomena.


28 Which of the following are radiation astronomy phenomena associated with velocity?

emitting neutrinos
red shift
undetectable with balloon-borne detectors
temporal spectroscopy
steady enough emission to be used as a standard for X-ray emission

29 True or False, Free-fall is associated with acceleration.


30 Using the speed of light a standard length is now used for the?

31 Various radiation observatories occur at different altitudes and geographic locations due to what effect?

the atmosphere of the Earth
the presence of oceans on the Earth
locally available carving tools
human habitation increases near an astronomical observatory
most astronomical objects are observed at night
currently dormant volcanoes seldom erupt

32 True or False, The NuSTAR observatory has a 10.14 m instrument focal length for its Wolter I telescopes.


33 Which of the following are phenomena associated with grid systems?

geographic coordinates
the Royal Observatory in Greenwich
French Institut Géographique National (IGN) maps
a longitude meridian passing through Paris
a local center of civilization

34 Complete the text:

Match up the item letter with each of the X-ray angular resolution possibilities below:
Rossi X-ray Timing Explorer - A
XMM-Newton - B
Chandra X-ray Observatory - C
Swift - D
Astro-rivelatore Gamma ad Imagini Leggero (AGILE) - E
Solar Heliospheric Observatory - F
Suzaku - G
Koronas-Foton - H









Hypotheses[edit | edit source]

  1. A speed requires a standardized distance (not necessarily a meter) divided by a standardized time (not necessarily an hour).

See also[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 1.2 P. K. Seidelmann (1976). Measuring the Universe The IAU and astronomical units. International Astronomical Union. Retrieved 2011-11-27.
  2. International Astronomical Union "SI units" accessed February 18, 2010. (See Table 5 and section 5.15.) Reprinted from George A. Wilkins & IAU Commission 5, "The IAU Style Manual (1989)" (PDF file) in IAU Transactions Vol. XXB

External links[edit | edit source]

{{Mathematics resources}}

{{Radiation astronomy resources}}{{Reasoning resources}}