Syncopated Systems
Seriously Sound Science
Messier objects to show: none → M1-45 → M46-80 → M81-103 → M104-109 → M110

Aerospace and Astronometric Distances

The table below includes notable distances from Earth’s surface used in aerospace and astronomy and their correlations, with Earth at the bottom and the farthest distance at the top, normalized to kilometers, and somewhat logarithmic in scale. (The table may be printed.)

Astronometry Table 1: An Ordered Survey of Aerospace and Astronometric Distances
Mean Distance/Altitude † Orbit Boundary Sphere Medium Space Proximity
~93 Gly (~8.8×1023 km) extent of observable universe (2020)  
intergalactic medium (IGM): galaxy filaments in void

intergalactic space (extragalactic space)

deep space
~4 Gly (~3.8×1022 km) Saraswati Supercluster (discovered 2017)  
~700 Mly (~6.6×1021 km) nearest edge of Horologium-Reticulum Supercluster  
~520 Mly (~4.9×1021 km) size of Local/Laniakea Supercluster (announced 2014)  
~200 Mly (~1.9×1021 km) Great Attractor (discovered 1986)
center of Local/Laniakea Supercluster
~9.8 Mly (~9.3×1019 km) extent of Local Group/start of Local Void        
~86 kly (~8.2×1017 km) far edge of Milky Way ‡        
16.73 ly (~1.6×1014 km) Altair        
4.37 ly (~4.2×1013 km) α-Centauri (Alpha Centauri)        
4.244 ly (~4.0×1013 km) Proxima Centauri  
interstellar medium (ISM)

interstellar space

deep space
~200 kau (~3.0×1013 km) extent of Solar System  
1 ly=9,460,730,472,580.8 km   Oort Cloud
~2 kau (~3.0×1011 km)    
148 au (~2.2×1010 km) Voyager 1 (2020, launched 1977)        
125 au (~1.9×1010 km) Pioneer 10 (2020, launched 1972)        
123 au (~1.8×1010 km) Voyager 2 (2020, launched 1977)        
121 au (~1.8×1010 km) heliopause        
103 au (~1.5×1010 km) Pioneer 11 (2020, launched 1973)        
~50 au (~7.5×109 km)          
46 au (~6.9×109 km) New Horizons (2020, launched 2006) Kuiper belt      
39.482 au (~5.9×109 km) ♇ 134340 Pluto (R=1,188.3 km, discovered 1930)      
30.11 au (~4.5×109 km) Neptune (R=24,622 km, discovered 1846)        
19.2184 au (~2.9×109 km) Uranus (R=25,362 km, discovered 1781)        
(~9.6 au) 1.43353×109 km  Saturn (R=58,232 km)        
(~5.2 au) 7.7857×108 km  Jupiter (R=69,911 km)  
interplanetary medium (IPM)

interplanetary space

deep space
~3.2 au (~4.8×108 km)    
    asteroid belt
~2.2 au (~3.3×108 km)    
(~1.5 au) 2.279392×108 km  Mars (R=3,389.5 km)        
1 au=149,597,870.7 km  Sun (R=695,700 km)        
0.723332 au (~1.1×108 km) Venus (R=6,051.8 km)        
0.387098 au (~5.8×107 km) Mercury (R=2,439.7 km)        
>6,300,000 (>6.3×106) km  night side magnetopause        
2,000,000 (2.0×106) km  ITU-R definition of deep space †        
~1,500,000 (~1.5×106) km  James Webb Space Telescope (JWST, launched 2021, positioned 2022) Sun-Earth L2 point
(extent of Earth’s Hill sphere)
      USA: deep
ITU-R: outer
~1,490,000 (~1.49×106) km  DSCOVR (heliocentric, launched 2015) Sun-Earth L1 point      
448,905 (~4.5×105) km  Earth-Moon L2 point ‡        
384,402 (~3.8×105) km  Moon (R=1,737.4 km)  
night side: magnetosphere & geospace (IPM elsewhere)

cislunar space

outer space
202,811 (~2.03×105) km  IBEX (launched 2008)    
192,201 (~1.9×105) km    halfway to Moon  
118,000 (1.18×105) km  Vela (launched 1963-1970)    
~90,000 (~9×104 km)   Earth’s bow shock
(~17 km thick)
  high Earth orbit (HEO)    
~10 RE (~6.4×104 km)   day side magnetopause        
~58,000 (~5.8×104) km             
35,786 (~3.6×104) km  geosynchronous equatorial orbit (GEO) Van Allen radiation belts (discovered 1958)

magnetosphere & geospace

cislunar space

outer space
~20,200 (~2.0×104) km  Global Positioning System (GPS) space vehicles
10,000 (1.0×104) km  medium Earth orbit (MEO)
2,000 (2.0×103) km           
~1,000 (~1.0×103) km             
low Earth orbit (LEO)   thermopause      
~640 (~6.4×102) km         
~500 (~5.0×102) km           
539 (~5.4×102) km  Hubble Space Telescope (HST)          
409 (~4.1×102) km  International Space Station (ISS)
(discovered 1902)


magnetosphere & geospace

cislunar space

outer space
160 (1.6×102) km   
400,000 ft (~122 km) NASA Space Shuttle entry interface
~110 (~1.1×102) km  turbopause          
100 (1.0×102) km  Kármán line          

cislunar space

near space
~85 km     
50 mi (~80 km) USA astronaut threshold    
~60 km     
~52.5 km    stratopause
20 km           
63,000 ft (~19.202 km) Armstrong limit   stratosphere      
FL600 (18 km)        
~13 km    tropopause   USA Class A airspace
8.848 km      troposphere    
Mount Everest      
18,000 ft (~5.5 km)        
0 km           
Earth (RE=6,371 km)


~ : Approximated/rounded
† : Distances greater than 2,000,000 km are relative to the Sun
‡ : Via calculation

Notable Catalogs

Below are summaries of notable astronomical catalogs indicating (as applicable) the nomenclature of objects identified by those catalogs and (as available) the year(s) of their publication.

Ancient Astronomy

Catalogs listed below were created before major advancements in astronometric technology:

Almagest (second century)
by Claudius Ptolemy (circa 100-170)
Book of Fixed Stars (circa 964)
by Abd al-Rahman al-Sufi (903-986)

Optical Telescopic Astronomy

Catalogs listed below were created approximately in the era after the invention and 1608 Dutch patent of the optical telescope:

M[1-45]: Catalogue des Nébuleuses et des Amas d’Étoiles (Catalog of Nebulae and Star Clusters, 1771 preliminary and 1774)
45 objects cataloged (and some discovered) by Charles Messier (1730-1817); with below additions, often referred to as Messier objects, Messier list, or Messier catalog
M[46-80] (1780)
included in version of above with 35 objects added by Charles Messier
M[81-103] (1781)
included in version of above with 23 objects added by Charles Messier
M[104-109] (1921-1950s)
included in version of above expanded to include 6 in unpublished notes of Charles Messier
M110 (1967)
included in version of above with object added based on notes of Charles Messier
H[1-1000]: Catalogue of Nebulae and Clusters of Stars (CN, 1786)
1000 objects cataloged by William Herschel (1738-1822) with assistance from his sister Caroline Herschel (1750-1848)
H[1001-2000]: (1789)
version of above with 1000 objects added by William Herschel and Caroline Herschel
H[2001-2500]: (1802)
version of above with 500 objects added by William Herschel and Caroline Herschel

Photographic Astronomy

Catalogs listed below were created approximately in the era after the invention and 1839 introduction of the word photography:

H[2501-5079]: General Catalogue of Nebulae and Clusters of Stars (GC, 1864)
version of above with 2579 objects added by William Herschel’s son John Herschel (1792-1871)
h[1-10,300]: General Catalogue of 10,300 Multiple and Double Stars (after 1871)
complement to GC, by John Herschel, published posthumously
NGC [1-7840]: The New General Catalogue of Nebulae and Clusters of Stars (1888)
compiled by John Louis Emil Dreyer (1852-1926)
IC [1-1520]: first Index Catalogue of Nebulae and Clusters of Stars (NGC/IC I, 1895)
supplement to above, adding 1520 objects
IC [1521-5386]: second Index Catalogue of Nebulae and Clusters of Stars (NGC/IC II, 1908)
supplement to above, adding 3866 objects
Mel [1-245]: A Catalogue of Star Clusters shown on Franklin-Adams Chart Plates (1915)
a catalog of 245 star clusters by British astronomer Philibert Jacques Melotte (1880-1961)
Cr [1-471]: On structural properties of open galactic clusters and their spatial distribution (1931)
a catalog of 471 open clusters by Swedish astronomer Per Collinder (1890-1974)

Electronic Astronomy

Catalogs listed below were created approximately in the era after the 1932 first detection of radio waves from space and 1937 first sky survey using radio astronometry:

HD [1-225,300]: Henry Draper Catalogue (1918-1924)
stars and their spectroscopic classifications by Henry Draper (1837-1882)
HDE [225,301-272,150]: Henry Draper Extension (1925-1936)
expanded above, classifying 46,850 more stars
HDEC [272,151-359,083]: Henry Draper Extension Charts (1937-1949)
expanded above, classifying 86,933 more stars
Sh1-[1-142]: first Sharpless catalog (Sh1, 1953)
list of H II regions (emission nebulae) compiled by Stewart Sharpless (1926-2013)
Sh2-[143-312]: second Sharpless catalog (Sh2, 1959)
expanded second and final version of above
The Revised New General Catalogue (RNGC, 1973)
compiled by Jack W. Sulentic and William G. Tifft
Herschel 400 Catalogue (circa 1980)
a subset of Herschel’s original catalog, selected by members of the of the Ancient City Astronomy Club in St. Augustine, Florida
NGC 2000.0 (1988)
compilation of the NGC and IC made by Roger W. Sinnott, using the J2000.0 coordinates
C[1-109]: Caldwell catalogue (1995)
compilation of the sky’s brightest deep-sky objects by Patrick Caldwell-Moore
The Revised New General Catalogue and Index Catalogue (RNGC/IC, 2009)
compiled by Wolfgang Steinicke
NGC/IC Project (1993-2017)
broad collaboration to identify all NGC and IC objects, correct mistakes, collect images and basic astronomical data