Determining Distances in Space

Determining Distances in Space

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I suspect the scope of this question may be to broad, but: what are some methods for determining distances between two objects in Space? Please present the methods in historical order, so as to make the evolution from primitive methods to modern ones clear.

There are a few methods that could be used to measure distances to objects in space. I'm not sure of the ages of these methods, but in many cases, the smaller-scaled methods tend to be older (as we simply didn't know about the larger scale).

The scale of the solar system was initially calculated using the parallax effect - measuring the position of Venus relative to the Sun at different times from several places across the Earth, during a transit. We can use orbital velocities nowadays to calculate average distances from the Sun. In some cases, we can use the light travel time to orbiting satellites to calculate distances very accurately, too.

For nearby stars, the main method is to measure the change in position of the star as the Earth moves across its orbit. This also uses the parallax effect.

For more distant stars, scientists often need to use specific variable stars (such as Cepheids, and RR Lyrae type stars), whose variations are related to their mass. Scientists can then use this data to calculate distance.

Cepheid variables are also used for measuring distances to nearby galaxies.

For more distant galaxies, scientists can use redshift to calculate distance, as more distant galaxies are receding faster than nearer ones, causing a larger doppler effect.

Another method for measuring extremely distant objects is to look for Type 1a supernovae, which, since they always have the same luminosity (their mass is always the Chandrasekhar limit, or about 1.4 solar masses). This was used to calculate that the expansion of the universe was accelerating. However, this method isn't used very often, as these supernovae don't happen very often.

In general, people's thumbs and fists are about:
size distance is (angle)
fist x 6 10°
thumb x 30
½ thumbx 60
¼ thumbx 120½°
Or you can just remember that your thumb is x30, and each time you halve your thumb, its twice as big.
  • Cars are about 4 meters (12 feet) long.
    A parked car across the street which is about 3 thumb-widths long is. 40 meters (120 feet) long. (12 / 3 x 30)
  • Cars are about 1.5 meters (5 feet) high.
    The same parked car is about 1 thumb high, so. 45 meters (150 feet). (1.5 m (or 5 ft) x 30)
    Notice this is only roughly the same as the previous estimate.
    How roughly is discussed in the next section.
  • Cars are about 2 meters (6 feet) wide.
    So the car, ahead of you on the road, which is 1/2 thumb wide, is roughly 120 meters (360 feet) away.
  • People are about 1-2 meters (3-6 feet) tall (kids/adults).
  • Office building floors are about 4 meters (10 feet) high.
    So if a 30 story building is 6° (two fingers) high, then its about 30 x 4 (or 10) x 20 = 2400 meters (6000 feet). so something like a mile away.
  • Airline jets are about 40 meters (150 feet) long.source[link broken]
    So a jet flying by and 1/4 thumb wide is about 150 x 120 = 18000 feet away (3+ miles).
    If its say 3 fists up (30°) [described below], then its 1/2 x 18000 = at about 9000 feet altitude, and about the the same 3'ish miles away on the ground.
  • How far away is that cloud?
    Clouds can come at different altitudes, so you need to find out the current cloud ceiling (how high the bottom of the clouds are). If the clouds are at 1500 feet, and the cloud you are interested in is say one fist up from the ground, then its approx 10 x 1500 = 15000 feet (3ish miles) away.
  • At WeatherNet, for instance under Massachusetts the Surface/METAR Observations for Boston, at the bottom (most recent) say something like
    KBOS 251756Z 10014KT 10SM FEW110 BKN250 04/M05 A3040 RMK AO2 SLP292 ACSL SE BKN LYR MSTLY THN T00441050 10050 20006
    where BKN250 means BroKeN clouds at 25,0oo feet.
  • UIUC gopher[link broken] (gopher?! Yes. At the moment (1997.Mar.25), its the best way I've found to get ceiling info.) has[link broken] but says "There are a number of problems here", and that they have stopped work on their gopher stuff.
  • The University of Wyoming[link broken], for instance has a line in the MAssachusets report where CeILing is 250oo feet.
  • You can call a recorded weather for pilots number. In the back of the phonebook White Pages, there are government blue pages, where it should be under United States Government, T, Transportation Department, Federal Aviation Admin, Pilot Automatic Terminal Information Service.

Why are light years used to measure distances in space?

The light year is used to measure distances in space because the distances are so big that a large unit of distance is required.


Distances in space are vast. The units of measurement we use from day to day are far too small to measure distances in space without adding a large number of zeros.

For example the metre was originally defined to be one millionth of the length of quarter great circle from the equator to a pole. This means that the circumference of the Earth is about 40,000 kilometres.

Now consider the distance from the Earth to the Sun. It is about 150,000 kilometres. The number is already getting big.

We added a new measurement the Astronomical Unit (AU) which is based on the average distance between the Earth and the Sun. This unit is good for measuring the distances between planets.

Now consider the nearest star from us Proxima Centauri. It is 40 trillion kilometres away which is a ridiculously large number. Expressed in AU this is 268,770 AU. However some stars are a lot further away and even AU numbers become huge.

The light year, as the name suggests, is the distance light travels in a year. It is about 10 trillion kilometres!

Proxima Centauri is 4.25 light years away, which is a much more manageable number.

Hence the light year is a convenient and manageable unit of distance for measuring the distance between objects in space.


  • Media Type: Digital/other
  • Features: Figures References Tables
  • Pagination: pp 280-290
  • Serial:
    • Transport
    • Volume: 33
    • Issue Number: 1
    • Publisher: Vilnius Gediminas Technical University (VGTU) Press
    • ISSN: 1648-4142
    • EISSN: 1648-3480
    • Serial URL:

    Table of Distances

    The Federal explosive regulations require explosives storage magazines to be located certain minimum distances from inhabited buildings, public highways, passenger railways, and other magazines based on the quantity of explosive materials in each magazine. These tables of distances were adopted to protect the public in the event of a magazine explosion.

    Tables of distances apply to the outdoor storage of explosive materials.

    When determining the distance from a magazine to a highway, an individual must measure from the nearest edge of the magazine to the nearest edge of the highway.

    If any two or more magazines are separated by less than the specified distance, then the weights in the magazines must be combined and considered as one.

    Each type of explosive has a specific table of distance.

    Tables of Distances




    Applying Table of Distances at § 555.218 and § 555.220

    The keys to applying these tables to donor/acceptor relationships are the net explosive weight (NEW) of the donor the distances between magazines the type of materials in the donor magazine and the type of materials in the acceptor magazine. When storing high explosives (HE), blasting agents (BA) and ammonium nitrate (AN):

    Multiply the minimum distance by 6 if unbarricaded.

    Use the proper column for acceptor (AN) (reduced sensitivity of AN acceptor is accounted for by table)?AN cannot be the donor in this relationship

    Use the proper column for the acceptor (BA or AN) (reduced sensitivity of acceptor is accounted for by table)

    Multiply distance by 6 if unbarricaded.

    Use the table at 555.218 to determine the required distance for the storage of blasting agents and ammonium nitrate from inhabited buildings, highways and passenger railways.

    § 555.218 Table of distances for storage of explosive materials (high)

    When two or more storage magazines are located on the same property, each magazine must comply with the minimum distances specified from inhabited buildings, railways, and highways, and, in addition, they should be separated from each other by not less than the distances shown for "Separation of Magazines," except that the quantity of explosives contained in cap magazines shall govern in regard to the spacing of said cap magazines from magazines containing other explosives. If any two or more magazines are separated from each other by less than the specified "Separation of Magazines" distances, then such two or more magazines, as a group, must be considered as one magazine.

    § 555.219 Table of distances for storage of low explosives

    Pounds Over Pounds Not Over From Inhabited building distance (feet) From public railroad and highway distance (feet) From above ground magazine (feet)
    0 1,000 75 75 50
    1,000 5,000 115 115 75
    5,000 10,000 150 150 100
    10,000 20,000 190 190 125
    20,000 30,000 215 215 145
    30,000 40,000 235 235 155
    40,000 50,000 250 250 165
    50,000 60,000 260 260 175
    60,000 70,000 270 270 185
    70,000 80,000 280 280 190
    80,000 90,000 295 295 195
    90,000 100,000 300 300 200
    100,000 200,000 375 375 250
    200,000 300,000 450 450 300
    § 555.220 Table of distances of ammonium nitrate and blasting agents from explosives or blasting agents

    Ammonium nitrate, by itself, is not considered to be a donor when applying this table. ammonium nitrate (AN), ammonium nitrate-fuel oil (ANFO) or combinations thereof are acceptors. If stores of AN are located within the sympathetic detonation distance of explosives or blasting agents, one-half the mass of the AN is to be included in the mass of the donor.

    Use the table at § 555.218 to determine required minimum distances from inhabited buildings, passenger railways, and public highways.


    Requirements for display fireworks, pyrotechnic compositions, and explosive materials used in assembling fireworks or articles pyrotechnic (excluding those in the process of manufacture, assembly, packaging, or transport).

    No more than 500 pounds (227 kg) of pyrotechnic compositions or explosive materials are permitted at one time in any fireworks mixing building, any building or area in which the pyrotechnic compositions or explosive materials are pressed or otherwise prepared for finishing or assembly, or any finishing or assembly building. All pyrotechnic compositions or explosive materials not in immediate use will be stored in covered, non-ferrous containers.

    The maximum quantity of flash powder permitted in any fireworks process building is 10 pounds (4.5 kg).

    All dry explosive powders and mixtures, partially assembled display fireworks, and finished display fireworks must be removed from fireworks process buildings at the conclusion of a day's operations and placed in approved magazines.

    § 555.222 Table of distances between fireworks process buildings and between fireworks process and fireworks non-process buildings

    Net weight (pounds) of fireworks, i.e. all pyrotechnic compositions, explosive materials and fuse only Display fireworks (feet) - barricaded double distance if unbarricaded Consumer fireworks (feet) - process buildings where consumer fireworks or articles pyrotechnic are processed
    0-100 57 37
    101-200 69 37
    201-300 77 37
    301-400 85 7
    401-500 91 37
    Above 500 Not permitted Not permitted

    Fireworks Process Building

    While consumer fireworks or articles pyrotechnic in a finished state are exempt, explosive materials used to manufacture or assemble such fireworks or articles are subject to regulation. Fireworks process buildings where consumer fireworks or articles pyrotechnic are being manufactured or processed must meet table of distance requirements.

    A maximum of 500 pounds of in-process pyrotechnic compositions, either loose or in partially-assembled fireworks, is permitted in any fireworks process building.

    Finished display fireworks may not be stored in a fireworks process building.

    A maximum of 10 pounds of flash powder, either in loose form or in assembled units, is permitted in any fireworks process building. Quantities in excess of 10 pounds must be kept in an approved magazine.

    § 555.223 Table of distances between fireworks process buildings and other specified areas

    Net weight (pounds) of fireworks, i.e. all pyrotechnic compositions, explosive materials and fuse only Display fireworks (feet) Consumer fireworks (feet) - process buildings where consumer fireworks or articles pyrotechnic are processed
    0-100 200 25
    101-200 200 50
    201-300 200 50
    301-400 200 50
    401-500 200 50
    Above 500 Not permitted Not permitted

    When calculating the distance from passenger railways, public highways, fireworks plant buildings used to store consumer fireworks and articles pyrotechnic, magazines and fireworks shipping buildings, and inhabited buildings:

    This table does not apply to the separation distances between fireworks process buildings (see § 555.222) and between magazines (see tables at §§ 555.218 and 555.224).

    The distances in this table apply with or without artificial or natural barricades or screen barricades. However, the use of barricades is highly recommended.

    No work of any kind, except to place/move items other than explosive materials from storage, may be conducted in any building designated as a warehouse. Fireworks plant warehouses are not subject to §§ 555.222 or 555.223.

    § 555.224 Table of distances for the storage of display fireworks (For bulk salutes, use table at § 555.218)

    For the purposes of applying this table, the term "magazine" also includes fireworks shipping buildings for display fireworks.

    Net weight (pounds) of firework, i.e. all pyrotechnic compositions, explosive materials and fuse only Distance between magazine and inhabited building, passenger railway, or public highway (feet) Distance between magazines (feet)
    0-1000 150 100
    1,001-5,000 230 150
    5,001-10,000 300 200
    Above 10,000 Use Table § 555.218

    For fireworks storage magazines in use prior to March 7, 1990, the distances in this table may be halved if properly barricaded between the magazine and potential receptor sites.

    Intergalactic Measurements

    Distances from the Earth to nearby stars can conveniently be expressed in parsecs for example, the nearest star, Proxima Centauri, is 1.295 parsecs distant. Because a parsec equals 3.27 light years, that's 4.225 light years. Even parsecs, however, prove inadequate for measuring distances within the galaxy or intergalactic distances. Astrophysicists frequently express these in kiloparsecs and megaparsecs, which equal 1,000 and 1 million parsecs, respectively. For example, the center of the galaxy is about 8 kiloparsecs distant, which equals 8,000 parsecs, or 26,160 light years. You’d need 16 digits to express that number with kilometers or miles.

    What Exactly Is A ‘Light-Year’ And Why Do Scientists Use Them To Measure Distances In Space?

    You’ve probably heard the term ‘light-year” a million times by now and if you’ve been paying attention in school you know that it’s a unit of measurement used by astronomers to calculate distances in space (not time). But what exactly is a “light-year” compared to our known miles or kilometers? And why do astronomers use this indeed weird measurement unit?

    Well, because we all love this kind of information, here you go:

    A light-year used by astronomers when measuring distances in space is, as its name implies, the distance a beam of light travels in one year. Compared to our known units of linear measurements, a light year equals six trillion miles (10 trillion kilometers). So why do scientists do things this way? Why not just use miles or kilometers? (the article continues after the ad)

    For two reasons actually. First of all, it’s because the distances in space are immersive. For example, our nearest star called Proxima Centauri is 24,000,000,000,000 miles away (yes, that’s the distance to our nearest star). So you can easily understand that if we go beyond that, we can quickly run into insanely unwieldy numbers. However, by using a bigger measuring unit, numbers become manageable – Proxima Centauri is just 4 light years away.

    Secondly, it’s convenient as light travels throughout space at exactly the same speed: approximately 670 million miles (1,110 million kilomerers) per hour. We don’t usually think of light travelling speed because we all assume that it’s instantaneous – you flick the switch and the light is on, right? Well, yeah, but it’s not actually instantaneous, it’s just extremely fast. In fact, travelling at that speed you would encircle the Earth eight times, get to the moon in one and a half seconds and teach the sun in eight minutes (yes, it takes eight minutes for the sun’s light to hit the Earth so we are actually looking into the past – how the sun was 8 minutes ago).

    If you take that to a greater scale though, things change: the light from a star located at one end of our galaxy takes 100,000 light-years to reach the other end. Hence, it immediately becomes apparent how convenient this unit of measurement is for astronomers to calculate these enormous, out-of-this-world (see what i did there?) distances in space.

    Factoring in design space when determining similarity of designs

    Article 23 of the Patent Law provides that a design for which a patent is granted must significantly differ from prior designs. Further, the similarity between a design patent and a prior design must be determined from the perspective of ordinary consumers in the relevant market.

    The following steps must be taken when determining the similarity of designs:

    • identifying all of the similarities and differences between the design patent and the prior design and
    • assessing the differences to determine whether they notably influence the overall visual effect of the patented product and thus make the design patent significantly different from the prior design, thus meeting the patentability requirement.

    As these steps must be taken from the standpoint of ordinary consumers, it is crucial to identify the knowledge and cognitive capability of consumers in the relevant market. To this end, the Supreme People's Court (SPC) uses certain parameters, including so-called 'design space'.

    In a retrial ruling concerning the administrative suit over an invalidation decision of a design patent, (1) the SPC &ndash for the first time &ndash defined 'design space' as the leeway a designer has when creating a specific design for a product.

    Not until the promulgation of Interpretation (II) of the SPC on Several Issues concerning the Application of Law in the Trial of Patent Infringement Dispute Cases (the SPC Interpretation), which came into force on 1 April 2016, had the court formally introduced the concept of design space in the legislation.

    Article 14 of the SPC Interpretation provides that:

    A people's court shall, when determining an ordinary consumer's knowledge and cognitive capability in terms of the design, take into account the design space of the products of the same or similar category in terms of the patented design, at the time when the alleged infringing act occurs. Where there is much design space, the people's court may determine that in general an ordinary consumer is unlikely to notice the minor differences between different designs. Where there is not much design space, the people's court may determine that in general an ordinary consumer is likely to notice the minor differences between different designs.

    In other words, if the product category has considerable design space, the difference between the design patent and the prior design has a relatively small effect on the overall visual appearance, making the design patent substantially similar to the prior design and thus unpatentable.

    This article analyses the application of the aforesaid provisions in a recent design patent administrative suit.

    Martell Corp initiated an invalidation administrative proceeding against a design patent ZL201430195369.1 titled "wine bottle", which is owned by a Chinese natural person. In the first-instance proceeding, the Beijing IP Court found the patent not significantly different from the prior design and revoked the invalidation decision in favour of the patentee.

    The patent design and prior design share the following features:

    • both are for hyaline glass bottles comprising a bottle stopper, bottle mouth, bottle neck and bottle body
    • the bottle stopper, bottle mouth and bottle neck are of the same shape and
    • the bottle body has in its front part an oblique plane extending from the bottle neck all the way down to the middle and lower part of the bottle body, and the shapes of the oblique planes are almost identical.

    The main differences between the two designs are as follows:

    • the shapes of the bottle bodies are different &ndash the bottle body of the patent design has vertical ridges. However, the bottle body of prior design is a smooth curved surface except for the oblique plane and
    • the bottom of the patent design is a regular octagon, but the bottom of the prior art is a circle.

    The patent design and the prior design are both designs of bottles, mainly used to contain liquid for storage, transportation and sale. Other than meeting the basic function, there is still considerate design space left for the shape of the bottle. For example, wine bottles &ndash as well as brandy bottles incorporating the patent design which are actually used by the patentee &ndash vary in shape, style and colour.

    In light of the considerable design space of products, the first-instance court found it unlikely that the aforesaid differences would significantly influence the overall visual appearance of the product because:

    • multiple vertical ridges on the bottle body can be clearly shown only in the top and bottom perspective views, but not from other perspectives, thus the difference does not produce a notable visual effect compared with the turning surface of the prior design and
    • it is highly unlikely that an ordinary consumer would pay attention to the bottom of the bottle during use and the bottom of the bottle does not produce a noticeable visual effect for an ordinary consumer.

    The court therefore concluded that the design patent, which had not been significantly different from the prior design, was unpatentable.

    Factoring in design space when ascertaining the similarity of designs could improve evaluation objectivity. In fact, in the Provisions of the SPC on Several Issues in the Trials of Administrative Cases involving the Granting and Affirmation of Patents (Draft), the SPC proposes the following parameters for assessing design space:

    • the product's function and use
    • the design density of prior designs
    • conventional designs
    • the necessary provisions of any laws or administrative regulations and
    • national or industry technology standards.

    The draft, which was released for public comment on 1 June 2018, is still in the pipeline. It remains to be seen how these parameters are evaluated in the final text.

    For further information on this topic please contact Hewen Zhao at Wanhuida Intellectual Property by telephone (+86 10 6892 1000) or email ([email protected]). The Wanhuida Intellectual Property website can be accessed at

    (1) SPC Retrial Administrative Judgment 5 (2010).

    The materials contained on this website are for general information purposes only and are subject to the disclaimer.

    ILO is a premium online legal update service for major companies and law firms worldwide. In-house corporate counsel and other users of legal services, as well as law firm partners, qualify for a free subscription.

    Determining Data Center Space Requirements

    The following excerpt from Datacate&rsquos Colocation Survival Guide discusses the steps required to accurately determine colocation space requirements, taking into consideration not only equipment but also constraints that may be imposed by the data center. Get the full Colocation Survival Guide here.

    How much space in the data center will your colocation require? This will primarily be determined by:

    • the equipment set that you plan to install
    • any minimum space allocation requirements imposed by your provider
    • any legal or regulatory requirements that may apply to your business or the application to be hosted by your colocation.

    In the data center, space is typically measured in standard cabinet/rack units, called &ldquoU&rdquo. A 1U space is equal to the usable width of the cabinet or rack (=< 19 inches), the usable depth of the cabinet (varies from 30 inches to 42 inches, 36 inches is common), and a vertical allocation that is exactly 1.75 inches high. The width and depth dimensions are constants, so you get more overall space by going vertical, i.e.: 2U = W x D x 3.5&rdquo, 4U = W x D x 7&rdquo, etc.


    Servers and other equipment that is specifically designed for data center rack or cabinet deployment will conform to the U form factor, and so you&rsquoll typically see servers and other devices described by their U size, i.e. a 1U network switch, a 2U server, etc. This makes determining your minimum space requirements easy: just add up the U factors for all of your equipment. If you have two 4U servers, three 1U servers and a 1U switch, you&rsquoll need no less than 12U for your colocation (you may need more if you are installing a PDU or other ancillary equipment).

    What if some or all your equipment is not designed for rack-mount applications? Examples would include tower or desktop servers, desktop external drives and desktop network appliances? In those cases, you&rsquoll need to grab a tape measure and do some figuring on your own, keeping in mind the usable width and depth available to you, and that standard cabinet U height. If you have a tower server that is 17&rdquo high or less, you can lay it on its side to better conform to cabinet/rack space distribution the server will fit in a 4U-5U space. With all non-rack-mount equipment, you will need to plan for a data cabinet shelf, which will support the equipment and will typically consume a U by itself.


    Some providers will have a minimum amount of space that you must take, whether or not you need it, so inquire as that will factor into your total cost. Also, if your colocation will be used to host electronic Protected Health Information (e-PHI), payment information such as credit card numbers or bank account numbers, or any other information that is considered sensitive or is governed by privacy laws or industry rules (HIPAA, PCI DSS), you must install your colocation in a private locking space with controlled access. That then becomes the determinate of the minimum space you must purchase, as private locking spaces are typically ½ cabinet (20U) in size, though a few providers do offer smaller locking spaces. Finally, if your colocation is large enough that it could occupy several full racks or cabinets, the provider may suggest that you consider a private cage. Cage space is sold by the square foot, with 80 &ndash 100 square feet typically being the minimum. In addition to the space, the provider would provision multiple power circuits, network drop(s), and may supply racks or cabinets within the cage for your equipment (sometimes you have the option of providing these yourself).

    TIP: Any decent modern data cabinet will be outfitted with both front and rear vertical post pairs for mounting of equipment. Shallow-depth devices, like network appliances, horizontal PDUs and even some smaller servers, can be mounted in a back-to-back configuration: one device mounted on the front posts, the other mounted directly behind it on the rear posts. In this way, two devices can share the same U, reducing your overall space requirements.

    Determining Distances in Space - Astronomy

    Opening a dental office is a significant step in a dentist’s career. It is also quite taxing. According to the ADA Center for Professional Success, taking it one organized step at a time can help alleviate some of the stress.

    One of the first major things you need to decide is the size and location of your ideal space.

    The size and location are based on your 10-year plan. This plan is how you envision your business to be functioning in ten years, in terms of maximum production. Having a 10-year plan will enable you to determine the number of operatories required to achieve your goals. Some dentists simply want to be sole proprietors, with a full-time hygienist and possibly another part-time hygienist. Others may want to hire an associate down the road or even run a multi-provider clinic.

    Once you have determined the number of operatories necessary to support your 10-year plan, you can determine the square footage you will need for your new office. Dental Office Design, published by the ADA, offers a formula that can be an excellent starting point to determine required square footage:

    Number of Operatories
    Multiplied by Square Footage of Operatories
    Divided by .275

    A full chapter excerpt from How to Open a New Dental Office or Relocate Your Current One on deciding how many operatories an office will need, how much square footage an office will require, and other preliminary decisions when choosing and constructing a dental space can be found here.

    Watch the video: Determining the Map Distance Between Genes (November 2022).